英文翻译
英文
Signal and System
1. Mathematical Representation of Signals
Anything that bears information can be considered a signal. Signals may describe a wide variety of physical phenomena. For example, speech, music, interest rates, the speed of an automobile are signals. Although signals can be represented in many ways, in all cases the information in a signal is contained in a pattern of variations of some form. For example, consider the human vocal mechanism, which produces speech by creating fluctuations in acoustic pressure.
The signal represents acoustic pressure variations as a function of time for the spoken words “should we chase.” The top line of the figure corresponds to the word “should,” the second line to the word “we,” and the last two lines to the word “chase.”
Signals are presented mathematically as functions of one or more independent variables. For example, a speech signal can be represented mathematically by acoustic pressure as a function of time, and a picture can be presented by brightness as a function of two spatial variables. For convenience, we will generally refer to independent variable as time, although it may not in fact represent time in specific time in specific applications. For example in geophysics, signals representing variations with depth of physical quantities such as density, porosity, and electrical resistivity are used to study the structure of the earth.
Two basic types of signals will be considered: continuous-time signal and discrete-time signal. In the case of continuous-time signals the independent variable is continuous, and thus these signals are defined for a continuum of values of the independent variable. On the other hand, discrete-time signals are defined only at discrete times, foe these signals, the independent variable takes on only a discrete set of values. A speech signals as a function of time and atmospheric pressure as a function of altitude are example of continuous-time signals. The weekly Dow-Jones stock market index is an example of a discrete-time signal. Other examples of discrete-time signals can be found in demographic studies in which various attributes, such as average budget, crime rate, or pounds of fish caught, are tabulated against such discrete variable as family size, total population, or type of fishing vessel, respectively.
To distinguish between continuous-time signals and discrete-time signals, we will use the symbol t to denote the continuous-time independent variable and n to denote the discrete-time independent. In addition, for continuous-time signals we will enclose the independent variable in parentheses (.), whereas for discrete-time signals we will use brackets [.] to enclose the independent variable. We will also have frequent occasions when it will be useful to represent signals graphically. It is important to note that the discrete-time signal x[n] is defined only for integer values of the independent variable. For further emphasis we will on occasion refer to x[n] as discrete-time sequence.
A discrete-time signal x[n] may represent a phenomenon for which the independent variable is inherently discrete. Signal such as demographic data are example of this .On the
other hand, a very important class of discrete-time signals arises from the sampling of continuous-time signals. In this case, the discrete-time signal x[n] represent successive samples of an underlying phenomenon for which the independent variable is continuous. No matter what source of the data, however, the signal x[n] is defined only for integer values of n. It makes no matter sense to refer to the 7/2th sample of a digital speech signal than it does to refer to the average budget of family with 5/2 family members.
2. Mathematical Representation of Systems
Physical systems in the broadest sense are an interconnection of components, devices, or subsystems. In contexts ranging from signal processing and communications to electromechanical motors, automotive vehicles, and chemical-processing plants, a system can be viewed as a process in which input signals are transformed by the system or cause the system to respond in some way, resulting in other signals as outputs, For example, a high fidelity system takes a recorded audio signal and generates a reproduction of that signal. If the hi-fi system has tone controls, we can change the tonal quality of the reproduced signal. Similarly, the circuit can be viewed as a system with input voltage x (t) and output voltage v (t), while the automobile can be thought of as a system with input equal to the force f (t) and output equal to the velocity v(t) of the vehicle An image-enhancement system transforms an input image into an output image that has some desired properties, such as improved contrast.
A continuous-time system is a system in which continuous-time input signals are applied and result in continuous-time output signals. Such as system will be represented pictorially as in FIG . 3-4(a), where x(t) is the input and y(t) is the output. Alternatively, we will often represent the input-output relation of a continuous-time system by the notation
X (t)→y(t)
Similarly, a discrete-time system-that is, a system that transforms discrete-time inputs into discrete-time outputs-will be depicted as in FIG .3-4(b) and will sometimes be represented symbolically as
X (n)→y(n)
X (t)
y (t) X (t) y (t)
Fig.3-4 (a) Continuous-time system; (b) Discrete-time system; Many real systems are built as interconnections of several subsystems. Be viewing such a system as an interconnection of its components, we can use our understanding of the components systems and of how they are interconnected in order to analyze the operation and behavior of the overall system. In addition, by describing a system in terms of an interconnection of simpler subsystems, we may in fact be able to define useful ways in which Continuous-time System Discrete-time System
to synthesize complex systems out of simpler, basic building blocks.
While one can construct a variety of system interconnections, there are several basic ones that are frequently encountered. A series or cascade information of two systems is illustrated in Fug.3-5(a). Diagrams such as this are referred to as block diagrams. Here, the output of System 1 is the input to System 2 and the overall system transforms an input by processing it first by System 1 and then by System 2 . An example of a series interconnection is a radio receiver followed by an amplifier. Similarly, one can define a series interconnection of three or more systems.
Input Output
(a)
(b)
(c)
Fig.3-5 Interconnection of two systems (a) series (cascade) interconnection;
(b) Parallel interconnection; (c) series-parallel interconnection
A parallel interconnection of two systems is illustrated in Fig.3-5(b).Here, the same input signal is applied t o systems 1to 2.the symbol ”⊕” in the figure denotes addition, so that the output of the parallel interconnection is the sum of the outputs of Systems 1 and 2. An example of a parallel interconnection is a simple audio system with several microphones feeding into a signal amplifier and speaker system. In addition to the simple parallel interconnection in Fig.3-8(b), we can define parallel interconnections more than two systems, and we can combine both cascade and parallel interconnection to obtain more complicated interconnections. An example of such an interconnection is given in Fig.3-5(c).
Another important type of system interconnection is a feedback interconnection, an example of which is illustrated in Fig.3-6. Here, the output of system 1 is the input to system 2, while the output of system 2 is fed back and added to the external input to produce the actual input to system 1. Feedback systems arise in a wide variety of applications. For example, a cruise control system on an automobile senses sense the vehicle’s velocity and adjusts the fuel Input
Output
System 1 System 2 ⊕ System 1 System 2 ⊕ System 1 System4 System 2 System 4 Input Output
Iutput flow in order to keep the speed at the desired level.
Fig.3-6 Feedback interconnection
3. Fourier Transforms and Frequency-Domain Description
Signals encountered in practice are mostly continuous-time signals and can be denoted as x (t), where t is a continuum. Although some signals such as stock markets, savings account and inventory are inherently discrete time, most discrete-time signals are obtained from continuous-time signals by sampling and can be denoted as x[n]:=x(n T), where T is sampling period and n is the time index and can assume only integers. Both x (t) and x[n] are functions of time and are called the time-domain description. In signal analysis, we study frequency contents of signals. In order to do so, we must develop a different but equivalent description, called the frequency-domain description. From the description, we can more easily determine the distribution of power in frequencies.
In digital processing of a continuous-time signal x (t), the first step is to select a sampling period T and then to sample x (t) to yield x(n T).It is clear that the smaller T is, the closer x (n T) is to x(t). However, a smaller T also requires more computation. Thus an important task in DSP is to find the largest possible T so that all information (if not possible, all essential information) of x(t) is retained in x(x T). Without the frequency-domain description, it is not possible to find such a sampling period. Thus computing the frequency content of signals is a first step in digital signal processing.
The frequency-domain description is developed from the Fourier transform. If the Fourier transform of a signal is defined, the transform is called the frequency spectrum of the signal that is
Fourier transform ←→frequency spectrum
The continuous-time Fourier transform is defined by the following pair of equations: Forward Continuous- Time Fourier Transform
X(j w)= e -jwt dt (3-1) And Inverse Continuous-Time Fourier Transform
X(t)=1/2错误！未找到引用源。e jwt
dt (3-2) ⊕ System 1 System 2 Output
F Equation (3-1) and (3-2) are referred to as the Fourier transform pair, with the function X(jw) referred to as Fourier Transform or Fourier integral of x(t) and eq. (3-2)as the inverse Fourier Transform equation. X(jw) is commonly referred to as the frequency-domain representation or the spectrum of the signal, as it provides us with the information needed for describing x(t) as a liner combination (specifically, an integral) of sinusoidal signals at different frequencies. Likewise, x(t) is the time-domain representation of the signal. We indicate this relationship between the two domains as
Time-Domain Frequency-domain
X (t) X (jw)
The notation F signifies that it is possible to go back and forth uniquely between the time-domain and the frequency-domain.
If we are given x(t) as a mathematical function, we can determine the corresponding spectrum function X(jw) by evaluating the integral in (3-1). In other words, (3-1) defines a mathematical operation for transforming x(t) into a new equivalent representation X(jw). It is common to say that we take the Fourier transform of x(t),meaning that we determine X(jw) so that we can use the frequency-domain representation of the signal.
Similarly, given X(jw) as a mathematical function, we can determine the corresponding time function x(t) using (3-2) by evaluating an integral, Thus, (3-2) defines the inverse Fourier transform operation that goes from the frequency-domain to the time-domain.
Armed with the powerful tool of Fourier transform, we will be able to (1) define a precise notion of bandwidth for a signal, (2) explain the inner workings of modern communication systems which are able to transmit many signals simultaneously by sharing the available bandwidth, and (3) define filtering operations that are needed to separate signals in such frequency-shared systems. There are many other applications of the Fourier transform, so it is safe to say that Fourier analysis provides the rigorous language needed to define and design modern engineering systems.
4. The Sampling Theorem
Under certain conditions, a continuous-time signal can be completely represented by and recoverable from a sequence of its values, or samples, at points equally space in time. This somewhat surprising property follows from a basic result that is referred to as the sampling theorem. This theorem is extremely important and useful. It is exploited, for example, in moving pictures, which consist of a sequence of individual frames, each of which represent an instantaneous view (i.e., a sample in time) of a continuously changing scene. When these samples are viewed in sequence at a sufficiently fast rate, we perceive an accurate representation of the original continuously moving scene.
Much of the important of the sampling theorem also lies in its role as a bridge between continuous-time signals and discrete-time signals. The fact that under certain conditions a continuous-time signal can be completely recovered from a sequence of its samples provides a mechanism for repressing a continuous-time signal by a discrete-time signal. In many contexts, processing discrete-time signals is more flexible and is often preferable to processing continuous-time signals. This is due in large part to the dramatic development of digital
technology over the past few decades, resulting in the availability of inexpensive, lightweight, and programmable, and easily reproducible discrete-time system. We exploit sampling to convert a continuous-time signal to a discrete-time signal, process the discrete-time signal using a discrete-time system, and then convert back to continuous-time signal.
Sampling theorem can be stated as follows:
Let x(t) be a band-limited signal with X(jw)=0 for |w|>wm. Then x(t) is uniquely determined by its samples x(nT),n=0,+1,-1 (i)
Ws>2w m
Where
W s=2错误！未找到引用源。/T
Given these samples, we can reconstruct x(t) by generating a periodic impulse train in which successive impulses have amplitudes that are successive sample values. This impulse train in which successive through an ideal low pass filter with gain T and cutoff frequency greater than w m and less than w s -2 w m. The resulting output signal will exactly equal x (t).
The frequency 2w m, which, under the sampling theorem, must be exceeded by the sampling frequency, is commonly referred to as the Nyquist rate.
In previous discussion, it was assumed that the sampling frequency was sufficiently high that the conditions of sampling theorem were met. With w s>2w m the spectrum of the sampled signal consists of scaled replications of the spectrum of x(t), and this forms the basis for the sampling theorem. When w s<2w m X(jw),the spectrum of x(t),is no longer replicated in X p(jw) and thus is no longer recoverable by lowpass filtering. The reconstructed signal will no longer be equal to x(t). This effect is referred to as aliasing.
Sampling has a number of important applications. One particularly significant set of applications relates to using sampling to process continuous-time signal with discrete-time systems, by means of minicomputers, or any of a variety of devices specifically oriented toward discrete-time signal processing.
中文
信号和系统
1信号的数学表示
承载信息的任何事物可以看作是一个信号。信号可以描述变化万千的物理现象。
例如，语言、音乐、利率、汽车的行驶速度等都是信号。虽然信号可以用许多方式来表示,但是在所有的情况下,信号所载有的信息总是包含在以某种形式变化的波形中。
例如，人的声道系统所产生的语音信号就是一种声压的起伏变化。
信号是描述的口语单词should we chase 声压随时间变化的函数，第一个波形对
应单词should，第二个是we,最后二个是chase。
信号在数学上表示为一个或多个自变量的函数。例如，一个语言信号在数学上可以用声压随时间变化的函数来表示，而一张照片可以表示为亮度随二维空间变量变化的函数。为了方便起见，通常用时间来表示自变量，尽管在某些具体应用中自变量不一定是时间。例如，在地球物理学研究中用于研究地球结构的一些物理量如密度，气隙度和电阻率就是随地球深度变化的信号。
信号分为二种基本类型：连续时间信号和离散时间信号。连续时间信号的自变量连续的，因此，这些信号定义为自变量的值是连续的一类信号，另一方面，离散时间信号只定义自变量是离散时刻的信号，这些信号的自变量只取一系列离散的值。作为时间函数的语言信号和随海拔高度变化的气压信号都是连续时间信号的例子。每周的道琼指数是离散时间信号的例子。在人口统计学的研究中可以找到其他离散信号的例子，例如像平均预算，犯罪率或捕鱼的重量等各种属性都可以分别对家庭大小、总人口数或捕鱼船的类型等离散变量列成表格。
为了区别连续时间信号和离散信号，我们用符号t 来表示连续时间自变量，用n 来表示离散时间自变量。另外，给连续时间信号的自变量加上圆括弧（.），给离散时间信号的自变量加上方括弧[.]。我们常常用图解的方法来表示信号。值得强调的是，离散时间信号x[n]仅仅在自变量的整数值上有定义。为了更进一步强调，有时我们把X[n] 看作是离散时间序列。
一个离散时间信号x[n] 可以描述一个自变量固有离散的现象，比如人口数据就是这类信号的例子。另一方面，一类非常重要的离散时间信号来源于连续时间信号的取样。既然这样，离散时间信号x[n] 描述了自变量是连续的基本现象的连续采样。
不管数据是什么来源，信号x[n] 只在n 为整数时有定义。所谓的一个数字语音信号的第7/2个样本和所谓的具有5/2个家庭平均预算一样都是毫无意义的。
2.系统的数学表示
广义的物理系统是各组成部分、设备、或子系统的互联。从信号处理、通讯到电机马达、机动车和化学处理设备，一个系统可看作输入信号的变换器或对输入信号做出某种响应而产生出另外的输出信号。例如，一个高保真度的系统对输入音频信号进行录制，并重现原输入信号。如果高保真系统有音调控制，我们可以改变重现信号的音质。同样地，电路可看作是输入电压为x(t)，输出电压为v(t)的系统，而汽车可看作是输入为动力f(t)，输出为汽车速度v(t)的系统。图像增强系统可改变一幅输入图像，使输出图像具有某些所需要的性质，比如增强图像对比度。
一个连续时间系统是施加连续时间输入信号，而产生连续时间输出信号的系统。这个系统的框图表示如图3-4（a）所示，其中x(t)为输入，y（t）为输出。另一方面，我们常用符号来表示连续时间系统的输入输出关系：x(t)→y(t)。
同样地，一个离散时间系统，将离散时间输入转为离散时间输出的描述如图3-4（b）所示，有时用符号描述为：x[n]→y[n]。
许多实际的系统由多个子系统互联而成。把这样一个系统看作是它的各组成部分的互联，可以用对各部分系统以及它们之间互联方式的理解来分析整个系统的作用和性能。另外根据简单系统的互联关系来描述一个系统，事实上可以通过定义有用的方法来简单基本的模块中合成复杂的系统。
当我们构造多种系统互联的时候，经常碰到几种基本的互联方式。二个系统的串联或级联如图3-5（a）所示，这种图称为框图。这里系统1的输出是系统2 的输入，整个系统首先按系统1 ，然后系统2 来变换输入。一个级联系统的例子是收音机接一个扩音器。类似的，级联可以是三个或更多需要连接。
二个系统的并联如图3-5（b）所示，在这里相同的输入信号施加于系统1和系统2.图中符号“⊕”表示相加，因此并联系统的输出系统1和系统2的输出之和。简单的音频系统是一个系统并联的例子，几个麦克风输入到一个单一放大器和扬声器系统。除了图3-5（b）所示的简单并联结构外，系统的比例可以是二个以上系统的并联，我们还可以将级联与并联结合在一起得到一种更为复杂的系统。图3-5（c）所示就是这种结构的例子。
另一种重要的系统互联是反馈系统，如图3-6所示。这里系统1的输出是系统2 的输入，而系统2的输出反馈回来与外加信号，一起组成系统1的实际输入。反馈系统有很广泛的应用。例如，汽车感应系统的巡航控制系统感应汽车的速度并调整燃油流量来保持所希望的速度。
3.傅里叶变换和频域描述
实际遇到的信号大多是连续时间信号，这类信号可以用x(t)表示，其中t 是连续变量。虽然有些信号，例如股票市场、储蓄账户和库存本来就是离散信号，但大多数离散时间信号，是从连续时间信号采样而来，可以表示为：x[n]=x（nT），其中T为采样周期，n为只能取整数的时间量。x(t)和x[n]都是时间函数，称为时域描述。在信号分析中，我们研究信号的频谱。为了能做到这一点，必须开发不同等效的描述方法，称为频域描述法。从这种描述中很容易确定频率的能量分布。
连续时间信号的数字处理，第一步是选择一个采样周期T，然后采样x(t)产生x(nT)。很明显，周期T越小，x(nT)越接近x(t)。然而，T越小计算量越大。因此，数字信号处理的一项重要任务，是要找出最大可能T，使x（t）的所有的信任然保留在x(nT)中。没有频域描述，就不可能找到采样周期。因此，数字信号处理的第一步是计算信号的频谱。
频域描述来自于傅里叶变换。信号的傅里叶变换称为信号的频谱
傅里叶变换←→频谱
连续时间傅里叶变换定义为下面的等式：连续时间傅里叶正变换：
X(j w)= e-jwt dt
连续时间傅里叶反变换：
X(t)=1/2e jwt dt
式（3-1）和式（3-2）称为傅里叶变换对，函数X(jw)称为x(t)的傅里叶变换和傅里叶积分，而式（3-2）称为傅里叶反变换。X(jw)通常称为信号的频域表示或信号的频谱，因为X（jw）告诉我们这样的一个信息，就是x(t)可以描述成不同频率的正弦信号的线性组合。同样，X（t）是信号的时域描述，我们表述这二种域之间的关系如下：
时域频域
F
X (t) X (jw)
其中，符号F表示时域和频域变换是一一对应的。
已知数学函数x(t),可以通过式（3-1）的积分运算得到相应的频谱函数X(jw)换句话，式（3-1）定义了一个数学运算，将x(t)变换为新的等效表示X（jw）。通常说得到了x(t)的傅里叶变换，就意味着确定了X(jw),这样我们就可以利用信号的频域表示方法。
同样，已知函数X(jw)，就是利用式（3-2）通过计算积分确定相应的时间函数x（t）。因此，式（3-2）得到了由频域到时域的傅里叶变换。
运用傅里叶变换这个强大工具，我们可以：1：确定一个信号带宽；2：解释通过共享可用带宽来同时发送多个信号的现代通信系统的内部工作机理；3：确定在这样的频率共享系统中分离信号的滤波方式。傅里叶变换有很多其他应用，也就是说，傅里叶分析为确定和设计现代工程系统提供了精确的方法。
4抽样理论
在一定的条件下，一个连续时间信号完全可以由该信号在时间等间隔点上的瞬时点上的瞬时值或样本值来表示，并且能用这些样本值恢复出信号来。这个性质来自于基本的结论，即抽样定理。这个定理非常重要并且得到了广泛的运用。例如，抽样定理在电影里得到了运用。电影由一组按时序排列的单个画面所组成，其中每个画面都代表着连续变化景象中的一个瞬时画面（即时间样本）。当这个画面以真够快的速率按顺序观看时，我们看到的是对原始连续影片的精确重现。
抽样理论的重要性同样在与它在连续时间信号和离散信号之间起了桥梁的作用。在一定条件下，可以用信号的时序样本值完全恢复出原连续时间信号，这就提供了用一个离散信号来表示一个连续时间信号的机理。在许多方面，处理离散时间信号要更加灵活些，因此往往比处理连续时间信号更为可取。这主要归功于在过去十几年高速发展的数字技术，使我们可以得到廉价，重量轻，可编程并且可容易复制的离散时间系统，我们利用抽样把连续信号转换成离散信号，通过离散时间系统来处理离散时间信号，然后再把离散时间信号转换成连续时间信号。
抽样定理如下：
假设x(t)是一个带宽受限信号，并且X(jw)=0，∣w∣>2w
m,其中w
s =2/T,
那么x(t)可以通过
它的样本值x(nT),n=0,……来唯一确定。
已知这些样本值，我们可以用以下方法重新构造x(t)：产生一个周期的冲激串，其冲击激强度就是一次而来的样本值，然后将冲激串通过一个增益为T，截止频率大于w
m，而小于w s -2 w m的理想低通滤波器，该滤波器的输出就等于x(t)。
在抽样定理中，采样频率必须大于2w m，频率2w m通常称作奈奎斯特抽样率。
在前面的讨论中，假设抽样频率足够高，因而满足抽样定理的条件。由于w s>2w m，取样信号的频谱是x（t）频谱的周期性延拓。这构成了抽样定理的基础。当w s<2w m，X（jw）即x(t)的频谱不再在X p(jw) 中复制，因此通过低通滤波器也不能恢复。重构的信号不再等于x(t)，这种现象称作频谱混叠。
抽样有许多重要的应用，一组特别重要的应用是利用微计算机，微处理器，或任何一个专门用于离散时间信号处理的器件，通过这些离散时间系统抽样来处理连续时间信号。
化学专业英语(修订版)翻译
01 THE ELEMENTS AND THE PERIODIC TABLE 01 元素和元素周期表 The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z. 质子的数量在一个原子的核被称为原子序数,或质子数、周淑金、电子的数量在一个电中性原子也等于原子序数松山机场的总质量的原子做出很近的总数的质子和中子在它的核心。这个总数被称为大量胡逸舟、中子的数量在一个原子,中子数,给出了a - z的数量。 The term element refers to, a pure substance with atoms all of a single kind. T o the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of the English name consisting of one or two letters, for example: 这个术语是指元素,一个纯物质与原子组成一个单一的善良。在药房“客气”原子的原子数来确定它,因为它的性质是决定其化学行为。目前所有原子和Z = 1 a到Z = 107是知道的;有107种化学元素。每一种化学元素起了一个名字和独特的象征。对于大多数元素都仅仅是一个象征的英文名称缩写形式,一个或两个字母组成,例如: oxygen==O nitrogen == N neon==Ne magnesium == Mg
美国大学校名英文缩写
美国大学校名英文缩写 英文缩写英文全称中文全称 AAMU Alabama A&M 阿拉巴马农业机械大学ADELPHI Adelphi University 艾德菲大学AMERICAN American University 美国大学 ANDREWS Andrews University 安德鲁大学 ASU Arizona State University 亚利桑那州立大学AUBURN Auburn University 奥本大学 -B- BAYLOR Baylor University 贝勒大学 BC Boston College 波士顿学院 BGSU Bowling Green State University 博林格林州立大学BIOLA Biola University 拜欧拉大学BRANDEIS Brandeis University 布兰迪斯大学BROWN Brown University 布朗大学 BSU Ball State University 波尔州立大学 BU* Boston University 波士顿大学 BU SUNY Binghamton 纽约州立大学宾厄姆顿分校BYU Brigham Young Univ. Provo 百翰大学 *BU通常意义上指Boston University -C- CALTECH California Institute of Technology 加州理工大学 CAU Clark Atlanta University 克拉克亚特兰大大学 CLARKSON Clarkson University 克拉逊大学CLARKU Clark University 克拉克大学CLEMSON Clemson University 克莱姆森大学 CMU* Carnegie Mellon University 卡耐基梅隆大学CMU Central Michigan University 中央密歇根大学COLUMBIA Columbia University 哥伦比亚大学CORNELL Cornell University 康奈尔大学CSU* Colorado State 科罗拉多州立大学 CSU Cleveland State University 克里夫立大学CU* University of Colorado Boulder 科罗拉多大学波德分校 CU University of Colorado Denver 科罗拉多大学丹佛分校 CUA Catholic University of America 美国天主教大学 CWRU Case Western Reserve Univ. 凯斯西储大学*CMU 通常意义上指 Carnegie Mellon University *CSU 通用 *CU 通用
应用化学专业英语翻译完整篇
1 Unit5元素周期表 As our picture of the atom becomes more detailed 随着我们对原子的描述越来越详尽，我们发现我们陷入了进退两难之境。有超过100多中元素要处理，我们怎么能记的住所有的信息？有一种方法就是使用元素周期表。这个周期表包含元素的所有信息。它记录了元素中所含的质子数和电子数，它能让我们算出大多数元素的同位素的中子数。它甚至有各个元素原子的电子怎么排列。最神奇的是，周期表是在人们不知道原子中存在质子、中子和电子的情况下发明的。Not long after Dalton presented his model for atom( )在道尔顿提出他的原子模型（原子是是一个不可分割的粒子，其质量决定了它的身份）不久，化学家门开始根据原子的质量将原子列表。在制定像这些元素表时候，他们观察到在元素中的格局分布。例如，人们可以清楚的看到在具体间隔的元素有着相似的性质。在当时知道的大约60种元素中，第二个和第九个表现出相似的性质，第三个和第十个，第四个和第十一个等都具有相似的性质。 In 1869,Dmitri Ivanovich Mendeleev,a Russian chemist, 在1869年，Dmitri Ivanovich Mendeleev ,一个俄罗斯的化学家，发表了他的元素周期表。Mendeleev通过考虑原子重量和元素的某些特性的周期性准备了他的周期表。这些元素的排列顺序先是按原子质量的增加,,一些情况中, Mendeleev把稍微重写的元素放在轻的那个前面.他这样做只是为了同一列中的元素能具有相似的性质.例如,他把碲(原子质量为128)防在碘(原子质量为127)前面因为碲性质上和硫磺和硒相似, 而碘和氯和溴相似. Mendeleev left a number of gaps in his table.Instead of Mendeleev在他的周期表中留下了一些空白。他非但没有将那些空白看成是缺憾，反而大胆的预测还存在着仍未被发现的元素。更进一步，他甚至预测出那些一些缺失元素的性质出来。在接下来的几年里，随着新元素的发现，里面的许多空格都被填满。这些性质也和Mendeleev所预测的极为接近。这巨大创新的预计值导致了Mendeleev的周期表为人们所接受。 It is known that properties of an element depend mainly on the number of electrons in the outermost energy level of the atoms of the element. 我们现在所知道的元素的性质主要取决于元素原子最外层能量能级的电子数。钠原子最外层能量能级（第三层）有一个电子，锂原子最外层能量能级（第二层）有一个电子。钠和锂的化学性质相似。氦原子和氖原子外层能级上是满的，这两种都是惰性气体，也就是他们不容易进行化学反应。很明显，有着相同电子结构（电子分布）的元素的不仅有着相似的化学性质，而且某些结构也表现比其他元素稳定（不那么活泼） In Mendeleev’s table,the elements were arranged by atomic weights for 在Mendeleev的表中，元素大部分是按照原子数来排列的，这个排列揭示了化学性质的周期性。因为电子数决定元素的化学性质，电子数也应该（现在也确实）决定周期表的顺序。在现代的周期表中，元素是根据原子质量来排列的。记住，这个数字表示了在元素的中性原子中的质子数和电子数。现在的周期表是按照原子数的递增排列，Mendeleev的周期表是按照原子质量的递增排列，彼此平行是由于原子量的增加。只有在一些情况下（Mendeleev注释的那样）重量和顺序不符合。因为原子质量是质子和中子质量的加和，故原子量并不完全随原子序数的增加而增加。原子序数低的原子的中子数有可能比原子序数高的原
当今最潮的英语翻译
伪球迷biased fans 紧身服straitjacket 团购group buying 奉子成婚shortgun marriage 婚前性行为premartial sex 开博to open a blog 家庭暴力family volience 问题家具problem furniture 炫富flaunt wealth 决堤breaching of the dike 上市list share 赌球soccer gambling 桑拿天sauna weather 自杀Dutch act 假发票fake invoice 落后产能outdated capacity 二房东middleman landlord 入园难kindergarten crunch 生态补偿ecological compensation 金砖四国BRIC countries 笑料laughing stock 泰国香米Thai fragrant rice 学历造假fabricate academic credentials 泄洪release flood waters 狂热的gaga eg: I was gaga over his deep blue eyes when I first set eyes on him 防暑降温补贴high temperature subsidy 暗淡前景bleak prospects 文艺爱情片chick flick 惊悚电影slasher flick 房奴车奴mortgage slave 上课开小差zone out 万事通know-it-all 毕业典礼commencement 散伙饭farewell dinner 毕业旅行after-graduation trip 节能高效的fuel-efficient 具有时效性的time-efficient 死记硬背cramming 很想赢be hungry for success 面子工程face job 捉迷藏play tag 射手榜top-scorer list 学历门槛academic threshold 女学究blue stocking
化学专业英语翻译1
01.THE ELEMENTS AND THE PERIODIC TABLE 01元素和元素周期 表。 The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z. 原子核中的质子数的原子称为原子序数，或质子数，卓电子数的电中性的原子也等于原子序数Z，总质量的原子是非常接近的总数量的质子和中子在原子核。这被称为质量数，这个数的原子中的中子，中子数，给出了所有的数量 The term element refers to, a pure substance with atoms all of a single kind. To the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of
应用化学专业英语第二版万有志主编版课后答案和课文翻译
Uｎit 1 The RｏotｓoｆCｈemisｔry Ｉ．Ｃoｍpreｈensioｎ. 1。Ｃ 2. Ｂ3．D 4. C 5. B ＩI。Ｍａｋe ａsenｔeｎｃe ｏut of ｅach ｉｔem ｂy reaｒranging ｔhe wordｓin ｂracｋets. 1.Tｈｅｐuｒiｆｉcation of aｎorganｉc compounｄis usually a matter of consｉｄerａｂlｅdｉfｆicｕｌtｙ, and iｔis nｅcｅｓsaｒy to eｍploy vａrious methoｄs fｏr thｉｓpurpｏse。 2.Science is an ｅｖeｒ－iｎcｒｅasing boｄy ofａccｕｍｕlａｔed anｄ ｓｙsｔｅmatiｚed knowledｇe ａnd iｓalsｏan activｉty bｙwｈic ｈｋnowledge iｓｇenerated。 3.Lifｅ，aftｅr all, is onｌy cｈeｍistry,in faｃｔ, a sｍall example of ｃ hｅｍistry ｏbsｅｒved oｎａsｉngle munｄane pｌａnet。 4.Peoplｅaｒe made of molｅculｅｓ; sｏmｅｏf ｔhｅmｏleculｅs in p ｅople aｒe rａｔher ｓimple whｅreas otｈerｓａｒｅhｉghly compｌex。 5.Chｅｍistry ｉｓever preseｎｔin ｏｕｒｌｉves frｏm ｂｉｒtｈ tｏｄeａthｂeｃａｕse withoｕt chｅmｉｓtrｙｔhere iｓneither life nor deａth. 6.Maｔhｅｍaｔics apｐeａｒs ｔo be almost as humaｎkiｎｄand ａｌ ｓo ｐermeaｔeｓall aspeｃts of ｈuman life, aｌthough ｍａｎｙof us are ｎｏｔfuｌly ａwａrｅoｆtｈis. III。Tｒanｓlatioｎ. 1.（a)chｅmicaｌprｏcess (b) natuｒal scienｃe（c）the teｃhｎｉ ｑｕe of distｉllaｔioｎ 2.Iｔｉs theａtｏｍs that ｍａkｅuｐｉron, waｔeｒ，oｘygen and the lｉke/anｄso on／aｎｄsｏfortｈ/aｎd otherｗiｓe. 3.Cheｍisｔｒy haｓa very long hｉｓtorｙ, ｉnｆaｃｔ，human a ｃtivity in chｅｍｉstrｙgｏes bａｃk ｔo ｐreｒecｏrｄed tｉmｅｓ/pｒedatiｎg reｃｏrded times． 4.Aｃcoｒdｉng to/Froｍthe eｖapoｒaｔion oｆwaｔeｒ，pｅople know ／reaｌized ｔｈat ｌiquidｓcａn ｔurn/bｅ/changeｉｎto gases ｕndeｒcertain conditions/circｕmsｔance／enｖironment。 5.Yoｕｍusｔknow ｔhe propｅｒtieｓｏfｔｈe materiaｌbeｆore y ｏu use it. IＶ．Ｔrａnslation 化学是三种基础自然科学之一,另外两种是物理和生物.自从宇宙大爆炸以来，化学过程持续进行,甚至地球上生命的出现可能也是化学过程的结果。人们也许认为生命是三步进化的最终结果,第一步非常快，其余两步相当慢.这三步
50个很潮的英文单词
发表日期：2015-09-29 07:48 来源：80后励志网编辑：80后点击：3321次 文章标签: 英语名言教育好文读书励志英语教育 文章导读:英语是国际性的语言，英语在我们的生活中使用率也越来越高，下面这50个很潮的英文单词，年轻人一定要学会哦！ 50个很潮的英文单词，年轻人一定要学会！ 1.预约券 reservation ticket 2.下午茶 high tea 3.微博 Microblog/ Tweets 4.裸婚 naked wedding 5.亚健康 sub-health 6.平角裤 boxers 7.愤青 young cynic 8.灵魂伴侣 soul mate 9.小白脸 toy boy 10.精神出轨 soul infidelity 11.人肉搜索 flesh search 12.浪女 dillydally girl 13.公司政治 company politics 14.剩女 3S lady(single，seventies,stuck)/left girls 15.山寨 copycat 16.异地恋 long-distance relationship 17.性感妈妈 yummy mummy ; milf(回复中指出的~) 18.钻石王老五 diamond bachelor;most eligible bachelor 20.时尚达人 fashion icon 21.御宅 otaku 22.上相的,上镜头的 photogenic 23.脑残体 leetspeak 24.学术界 academic circle 25.哈证族 certificate maniac 26.偶像派 idol type 27.住房公积金 housing funds 28.个税起征点 inpidual income tax threshold 29.熟女 cougar(源自电影Cougar Club) 30.挑食者 picky-eater 31.伪球迷 fake fans 32.紧身服 straitjacket 33.团购 group buying 34.奉子成婚 shotgun marriage 35.婚前性行为 premarital sex 36.开博 to open a blog 37.家庭暴力 family/domestic violence (由回复更正) 38.问题家具 problem furniture
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Unit 1 Chemical Industry 化学工业 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin‘s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). 1．化学工业的起源 尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。可以认为它起源于工业革命其间，大约在1800年，并发展成为为其它工业部门提供化学原料的产业。比如制肥皂所用的碱，棉布生产所用的漂白粉，玻璃制造业所用的硅及Na2CO3. 我们会注意到所有这些都是无机物。有机化学工业的开始是在十九世纪六十年代以William Henry Perkin 发现第一种合成染料—苯胺紫并加以开发利用为标志的。20世纪初，德国花费大量资金用于实用化学方面的重点研究，到1914年，德国的化学工业在世界化学产品市场上占有75%的份额。这要归因于新染料的发现以及硫酸的接触法生产和氨的哈伯生产工艺的发展。而后者需要较大的技术突破使得化学反应第一次可以在非常高的压力条件下进行。这方面所取得的成绩对德国很有帮助。特别是由于1914年第一次世界大仗的爆发，对以氮为基础的化合物的需求飞速增长。这种深刻的改变一直持续到战后（1918-1939）。 date bake to/from: 回溯到 dated: 过时的，陈旧的 stand sb. in good stead: 对。。。很有帮助
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应用化学专业英语及答案
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化工专业英语lesson4翻译汇编
仅供参考 Introduction to Organic Chemistry 1. Sources of Organic Compounds The major sources of organic chemicals are coal, petroleum, and agricultural products. Both coal and petroleum were formed through the geologic processes of changing animal and plant remains into carbon-containing residues. About one-third of all organic chemicals are derived from coal and about one-half from the petroleum industry 有机化合物的来源 有机化学药品的主要来源是煤、石油和农产品。动植物的遗体通过地质作用变成含碳残基然后形成煤和石油。三分之一的所有有机化合物品是从煤中得到的，一般来自于石油工业。 2. The Methods and Objectives of Organic Chemistry Because of the tremendous number of organic compounds known, and of the many more being synthesized daily, the study of organic chemistry is not the study of individual compounds, it is the study of groups or families of compounds all closely related to each other. Obviously, the former approach would be prohibitive[prE5hibitiv]. Once the structural relationships of certain typical members of a particular group or family of compounds are understood, these structural features are understood for any one of the many members of the family, even though some may not be known compounds. 因为已知的有机化合物的数目庞大，而且还在逐日合成更多的品种，所以有机化学不是研究单个的化合物，而是把彼此密切相关的化合物按类或族来研究。显然，以前的方法是不可取的，一旦典型的一类特殊化合物被认识，这些结构特征将适用于这类化合物，甚至是一些未知的化合物， For each group or family of compounds often called homologous series of compounds, structural features are important. In studying organic chemistry, it is not enough to know the identities of the elements and how many atoms of each element are present in a given molecule. More importantly, the order in which these atoms are linked together to form
南京高校中英文校名集锦
南京大学Nanjing University 东南大学Southeast University 南京航空航天大学Nanjing University of Aeronautics and Astronautics 南京理工大学Nanjing university ofscience ＆technology 南京工业大学Nanjing tech university 南京邮电大学Nanjing University of Posts and Telecommunications 南京林业大学Nanjing forestry university 南京信息工程大学Nanjing University of Information Science & Technology 南京农业大学Nanjing Agricultural University 南京医科大学Nanjing medical university 南京中医药大学Nanjing university of Chinese medicine 中国药科大学China Pharmaceutical University 南京师范大学Nanjing Normal University 南京财经大学Nanjing University Of Finance & Economics 江苏警官学院Jiangsu police institute 南京体育学院Nanjing Sport Institute 南京艺术学院Nanjing University of the Arts 三江学院Sanjiang university 南京工程学院Nanjing institute of technology 南京审计大学Nanjing audit university 南京晓庄学院Nanjing xiaozhuang university 南京特殊教育师范学院Nanjing Normal University Of Special Education 南京森林警察学院Nanjing forest police college 东南大学成贤学院southeast university chengxian college 金陵科技学院jinling institute of technology 南京大学金陵学院Nanjing university jinling college 南京理工大学紫金学院Nanjing University of Science and Technology ZiJin College 南京航空航天大学金城学院 nanhang Jincheng college 中国传媒大学南广学院Communication University of China, Nanguang College
应用化学专业英语翻译(第二版)
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50个很潮的英文单词
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20.时尚达人 fashion icon 21.御宅 otaku 22.上相的,上镜头的 photogenic 23.脑残体 leetspeak 24.学术界 academic circle 25.哈证族 certificate maniac 26.偶像派 idol type 27.住房公积金 housing funds 28.个税起征点 inpidual income tax threshold 29.熟女 cougar(源自电影Cougar Club) 30.挑食者 picky-eater 31.伪球迷 fake fans 32.紧身服 straitjacket 33.团购 group buying 34.奉子成婚 shotgun marriage 35.婚前性行为 premarital sex 36.开博 to open a blog 37.家庭暴力 family/domestic violence (由回复更正) 38.问题家具 problem furniture 39.炫富 flaunt wealth 40.决堤 breaching of the dike 41.上市 list share 42.赌球 soccer gambling 43.桑拿天 sauna weather 44.自杀 Dutch act 45.假发票 fake invoice 46.落后产能 outdated capacity 47.二房东 middleman landlord 48.入园难 kindergarten crunch 49.生态补偿 ecological compensation 50.金砖四国 BRIC countrie
应用化学专业英语翻译
１０级应用化学（2）班郑禄春 B2０1０06３224 Lessｅn ２4 ChemicａｌＲeaｃtionｓ Conseｒvation of mａｓs ａnd ｅｎergy(质量与能量守恒) Ｔwo ｃonseｒvaｔｉｏn laws（定律) apｐlｙｔo aｌｌｃhemical reaｃtionｓ: E ｎergy can neitheｒ be cｒｅated nｏr deｓtroｙed, anｄｍａｔteｒｃaｎneither ｂｅ created nor deｓtｒｏyed. Thus the ａtoms taking part in a chemical reactioｎ may be reａrrangｅd, bｕt all ｔhe atoms preseｎt ｉn the reacｔan ｔs must also be preｓent in ｔhe prodｕctｓ, and the tｏtaｌｍasｓ oｆ tｈe ｒeactants muｓt equaｌ thｅｔotaｌｍａss ｏｆthe prｏducts. 化学反应 质量守恒和能量守恒 两个守恒定律(定律)适用于所有的化学反应:能量既不能创造也不能消灭,物质也不能创造也不能消灭。因此原子参与化学反应可能重新安排，但所有的原子出现在反应物必须包含在产品,反应物的总质量必须等于生产物的总质量。 What is ａ chｅmicaｌ reaction? A chｅmicaｌreaｃtiｏn occｕｒs whｅn sｕbsｔａnｃes (tｈe ｒｅactantｓ) colｌide (碰撞）ｗiｔh ｅnouｇｈ energｙ tｏｒearｒａnge to form difｆerent c ｏｍpounds (ｔhe ｐrｏdｕcts）. The changｅ iｎ enerｇy that occurs wheｎ a reaction take pｌａｃe ｉs deｓcriｂed by therｍｏdｙｎaｍics（热力学）anｄt ｈe ｒａｔｅ oｒ speed at which a reacｔioｎocｃurｓis descｒibed by kiｎeticｓ (动力学) . Reacｔions in ｗhiｃh ｔｈe ｒeaｃtａnｔｓaｎd ｐrｏductｓcoｅxist arｅ coｎｓidｅｒed ｔo be in equilｉｂriuｍ(处于平衡）. A chｅｍiｃａl ｅｑuaｔion ｃonsｉｓts ｏf the ｃhemｉｃal fｏrmｕｌａ（化学式)of thｅ rea ｃｔants, and ｔhe cｈemical fｏｒmｕla of ｔhe ｐrodｕcts. The twｏａre separateｄ bｙａn → uｓually read aｓ“yｉelｄs”ａnｄeach ｃhemicａl forｍula is sｅpａｒatｅd frｏm otheｒs by ａ plus sｉgn (加号）． Sometime ｓ a trｉangｌe is dｒawｎ over ｔhe arrow symbol tｏｄenotｅ enerｇy ｍuｓt ｂe addeｄｔo ｔｈe subsｔances ｆor ｔhe ｒeａcｔiｏn to beｇｉn． Eａch ｃｈemiｃaｌ formula may be pｒｅｃeded by a sｃalaｒ（数量的) ｃoｅｆficienｔｉndicatｉng thｅ proｐorｔion (比例) ｏｆ that substaｎce nｅｃｅssary to ｐｒoｄｕce ｔhe rｅacｔion in forｍulａ. Foｒinstanｃe， thｅｆoｒmｕla ｆoｒ the buｒning of mｅthane(CH4 + 2O2 →ＣO2 + 2H2O） iｎdｉｃates that twｉce as much Ｏ2 aｓ CH４ iｓ nｅｅded, and wｈen tｈey reａct， twicｅas ｍuch H2O as ＣO2 wｉll be produceｄ. This is ｂecａuse durｉng tｈe reａctiｏｎ，each atom ｏｆ cａrbon needｓ eｘａctlｙ two atoms ｏf oxygen ｔo combｉnｅ with, to ｐroduｃe the CO2, and ｅvｅry twｏaｔｏms of ｈydrｏgen need an atｏm ｏf oxygen tｏcombine wiｔｈｔo proｄuce ｔhｅH２O． If thｅ pｒｏportiｏns ｏf thｅ reactaｎtｓarｅ nｏｔ reｓpecｔed, when ｔhey arｅ foｒｃｅd ｔｏreacｔ, eitheｒ not all oｆｔhe ｓuｂstance used wilｌparticipate in tｈe re ａｃｔion, or the reａctiｏｎ that wｉll take pｌace ｗilｌbｅ dｉｆfｅｒent ｆｒom tｈe ｏne noteｄin ｔhｅ equatｉon.. 什么是化学反应 一个化学反应发生在物质（反应物）碰撞有足够的能量去重新排列,形成不同的化合物(产品）。当反应发