计算机英文参考文献翻译-英语论文.doc

计算机英文参考文献翻译-英语论文计算机英文参考文献翻译birth of the netthe internet has had a relatively brief, but explosive history so far. it grew out of an experiment begun in the 1960s by the u.s. department of defense. the dod wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. if part of the network were damaged or destroyed, the rest of the system still had to work. that network was arpanet, which linked u.s. scientific and academic researchers. it was the forerunner of todays internet. in 1985, the national science foundation (nsf) created nsfnet, a series of networks for research and education communication. based on arpanet protocols, the nsfnet created a national backbone service, provided free to any u.s. research and educational institution. at the same time, regional networks were created to link individual institutions with the national backbone service. nsfnet grew rapidly as people discovered its potential, and as new software applications were created to make access easier. corporations such as sprint and mci began to build their own networks, which they linked to nsfnet. as commercial firms and other regional network providers have taken over the operation of the major internet arteries, nsf has withdrawn from the backbone business. nsf also coordinated a service called internic, which registered all addresses on the internet so that data could be routed to the right system. this service has now been taken over by network solutions, inc., in cooperation with nsf. how the web worksthe world wide web, the graphical portion of the internet, is the most popular part of the internet by far. once you spend time on the web,you will begin to feel like there is no limit to what you can discover. the web allows rich and diverse communication by displaying text, graphics, animation, photos, sound and video. so just what is this miraculous creation? the web physically consists of your personal computer, web browser software, a connection to an internet service provider, computers called servers that host digital data and routers and switches to direct the flow of information. the web is known as a client-server system. your computer is the client; the remote computers that store electronic files are the servers. heres how it works: lets say you want to pay a visit to the the louvre museum website. first you enter the address or url of the website in your web browser (more about this shortly). then your browser requests the web page from the web server that hosts the louvres site. the louvres server sends the data over the internet to your computer. your web browser interprets the data, displaying it on your computer screen. the louvres website also has links to the sites of other museums, such as the vatican museum. when you click your mouse on a link, you access the web server for the vatican museum. the glue that holds the web together is called hypertext and hyperlinks. this feature allow electronic files on the web to be linked so you can easily jump between them. on the web, you navigate through pages of information based on what interests you at that particular moment, commonly known as browsing or surfing the net. to access the web you need web browser software, such as netscape navigator or microsoft internet explorer. how does your web browser distinguish between web pages and other files on the internet? web pages are written in a computer language called hypertext markup language or html.some web historythe world wide web (www) was originally developed in 1990 at cern, the european laboratory for particle physics. it is now managed by the world wide web consortium, also known as the world wide web initiative. the www consortium is funded by a large number of corporate members, including at&t, adobe systems, inc., microsoft corporation and sun microsystems, inc. its purpose is to promote the growth of the web by developing technical specifications and reference software that will be freely available to everyone. the consortium is run by mit with inria (the french national institute for research in computer science) acting as european host, in collaboration with cern. the national center for supercomputing applications (ncsa) at the university of illinois at urbana-champaign, was instrumental in the development of early graphical software utilizing the world wide web features created by cern. ncsa focuses on improving the productivity of researchers by providing software for scientific modeling, analysis, and visualization. the world wide web was an obvious way to fulfill that mission. ncsa mosaic, one of the earliest web browsers, was distributed free to the public. it led directly to the phenomenal growth of the world wide web.nderstanding web addresses you can think of the world wide web as a network of electronic files stored on computers all around the world. hypertext links these resources together. uniform resource locators or urls are the addresses used to locate these files. the information contained in a url gives you the ability to jump from one web page to another with just a click of your mouse. when you type a url into your browser or click on a hypertext link, your browser is sending a request to a remote computer to download a file. what does a typical url look like? here are some examples:the home page for study english. a directory of files at mit* available for downloading. a newsgroup on rose gardening. the first part of a url (before the two slashes* tells you the type of resource or method of access at that address. for example: http - a hypertext document or directory gopher - a gopher document or menu ftp - a file available for downloading or a directory of such files news - a newsgroup telnet - a computer system that you can log into over the internet wais* - a database or document in a wide area information search database file - a file located on a local drive (your hard drive) the second part is typically the address of the computer where the data or service is located. additional parts may specify the names of files, the port to connect to, or the text to search for in a database. you can enter the url of a site by typing it into the location bar of your web browser, just under the toolbar. most browsers record urls that you want to use again, by adding them to a special menu. in netscape navigator, its called bookmarks. in microsoft explorer, its called favorites. once you add a url to your list, you can return to that web page simply by clicking on the name in your list, instead of retyping the entire url. most of the urls you will be using start with http which stands for hypertext transfer protocol*. http is the method by which html files are transferred over the web. here are some other important things to know about urls:a url usually has no spaces. a url always uses forward slashes (/). if you enter a url incorrectly, your browser will not be able to locate the site or resource you want. should you get an error message or the wrong site, make sure you typed the address correctly. you can find the url behind any link by passing your mouse cursor over the link. the pointer will turn into a hand and the url will appear in the browsers status bar, usually located at the bottom of your screen.907计算机英文参考文献翻译domain nameswhen you think of the internet, you probably think of .com. just what do those three letters at the end of a world wide web address mean? every computer that hosts data on the internet has a unique numerical address. for example, the numerical address for the white house is 00. but since few people want to remember long strings of numbers, the domain name system (dns)* was developed. dns, a critical part of the internets technical infrastructure*, correlates* a numerical address to a word. to access the white house website, you could type its number into the address box of your web browser. but most people prefer to use in this case, the domain name is . in general, the three-letter domain name suffix* is known as a generic top-level domain and describes the type of organization. in the last few years, the lines have somewhat blurred* between these categories. .com - business (commercial) .edu - educational .org - non-profit .mil - military .net - network provider .gov - government a domain name always has two or more parts separated by dots and typically consists of some form of an organizations name and the three-letter suffix. for example, the domain name for ibm is ; the united nations is . if a domain name is available, and provided it does not infringe* on an existing trademark, anyone can register the name for $35 a year through network solutions, inc., which is authorized to register .com, .net and .org domains. you can use the box below to see if a name is a available. dont be surprised if the .com name you want is already taken, however. of the over 8 million domain names, 85% are .com domains. icann, the internet corporation for assigned names and numbers, manages the domain name system. as of this writing, there are plans to add additional top-level domains, such as .web and .store. when that will actually happen is anybodys guess. to check for, or register a domain name, type it into the search box.it should take this form: in addition to the generic top-level domains, 244 national top-level domains were established for countries and territories*, for example: .au - australia .ca - canada .fr - france .de - germany .uk - united kingdom for us $275 per name, you can also register an international domain name with net names. be aware that some countries have restrictions for registering names. if you plan to register your own domain name, whether its a .com or not, keep these tips in mind: the shorter the name, the better. (but it should reflect your family name, interest or business.) the name should be easy to remember. it should be easy to type without making mistakes. remember, the internet is global. ideally, a domain name will read in a language other than english. about modem telephone lines were designed to carry the human voice, not electronic data from a computer. modems were invented to convert digital computer signals into a form that allows them to travel over the phone lines. those are the scratchy sounds you hear from a modems speaker. a modem on the other end of the line can understand it and convert the sounds back into digital information that the computer can understand. by the way, the word modem stands for modulator/demodulator. buying and using a modem used to be relatively easy. not too long ago, almost all modems transferred data at a rate of 2400 bps (bits per second). today, modems not only run faster, they are also loaded with features like error control and data compression. so, in addition to converting and interpreting signals, modems also act like traffic cops, monitoring and regulating the flow of information. that way, one computer doesnt send information until the receiving computer is ready for it. each of these features, modulation, error control, and data compression, requires a separate kind of protocol and thats what some of those terms you see like v.32, v.32bis, v.42bis and mnp5 refer to. if your computer didnt come with an internal modem, consider buying an external one, because it is much easier to install and operate. for example, when your modem gets stuck (not an unusual occurrence), you need to turn it off and on to get it working properly. with an internal modem, that means restarting your computer-a waste of time. with an external modem its as easy as flipping a switch. heres a tip for you: in most areas, if you have call waiting, you can disable it by inserting *70 in front of the number you dial to connect to the internet (or any online service). this will prevent an incoming call from accidentally kicking you off the line. this table illustrates the relative difference in data transmission speeds for different types of files. a modems speed is measured in bits per second (bps). a 14.4 modem sends data at 14,400 bits per second. a 28.8 modem is twice as fast, sending and receiving data at a rate of 28,800 bits per second. until nearly the end of 1995, the conventional wisdom was that 28.8 kbps was about the fastest speed you could squeeze out of a regular copper telephone line. today, you can buy 33.6 kbps modems, and modems that are capable of 56 kbps. the key question for you, is knowing what speed modems your internet service provider (isp) has. if your isp has only 28.8 kbps modems on its end of the line, you could have the fastest modem in the world, and only be able to connect at 28.8 kbps. before you invest in a 33.6 kbps or a 56 kbps modem, make sure your isp supports them. speed it upthere are faster ways to transmit data by using an isdn or leased line. in many parts of the u.s., phone companies are offering home isdn at less than $30 a month. isdn requires a so-called isdn adapter instead of a modem, and a phone line with a special connection that allows it to send and receive digital signals. you have to arrange with your phone company to have this equipment installed. for more about isdn, visit dan kegels isdn page. an isdn line has a data transfer rate of between 57,600 bits per second and 128,000 bits per second, which is at least double the rate of a 28.8 kbps modem. leased lines come in two configurations: t1 and t3. a t1 line offers a data transfer rate of 1.54 million bits per second. unlike isdn, a t-1 line is a dedicated connection, meaning that it is permanently connected to the internet. this is useful for web servers or other computers that need to be connected to the internet all the time. it is possible to lease only a portion of a t-1 line using one of two systems: fractional t-1 or frame relay. you can lease them in blocks ranging from 128 kbps to 1.5 mbps. the differences are not worth going into in detail, but fractional t-1 will be more expensive at the slower available speeds and frame relay will be slightly more expensive as you approach the full t-1 speed of 1.5 mbps. a t-3 line is significantly faster, at 45 million bits per second. the backbone of the internet consists of t-3 lines. leased lines are very expensive and are generally only used by companies whose business is built around the internet or need to transfer massive amounts of data. isdn, on the other hand, is available in some cities for a very reasonable price. not all phone companies offer residential isdn service. check with your local phone company for availability in your area. cable modems a relatively new development is a device that provides high-speed internet access via a cable tv network. with speeds of up to 36 mbps, cable modems can download data in seconds that might take fifty times longer with a dial-up connection. because it works with your tv cable, it doesnt tie up a telephone line. best of all, its always on, so there is no need to connect-no more busy signals! this service is now available in some cities in the united states and europe. the download times in the table above are relative and are meant to give you a general idea of how long it would take to download different sized files at different connection speeds, under the best of circumstances. many things can interfere with the speed of your file transfer. these can range from excessive line noise on your telephone line and the speed of the web server from which you are downloading files, to the number of other people who are simultaneously trying to access the same计算机英文参考文献翻译file or other files in the same directory. dsl (digital subscriber line) is another high-speed technology that is becoming increasingly popular. dsl lines are always connected to the internet, so you dont need to dial-up. typically, data can be transferred at rates up to 1.544 mbps downstream and about 128 kbps upstream over ordinary telephone lines. since a dsl line carries both voice and data, you dont have to install another phone line. you can use your existing line to establish dsl service, provided service is available in your area and you are within the specified distance from the telephone companys central switching office. dsl service requires a special modem. prices for equipment, dsl installation and monthly service can vary considerably, so check with your local phone company and internet service provider. the good news is that prices are coming down as competition heats up.websitesanatomy of a web pagea web page is an electronic document written in a computer language called html, short for hypertext markup language. each web page has a unique address, called a url* or uniform resource locator, which identifies its location on the network. a website has one or more related web pages, depending on how its designed. web pages on a site are linked together through a system of hyperlinks* , enabling you to jump between them by clicking on a link. on the web, you navigate through pages of information according to your interests. home sweet home pagewhen you browse the world wide web youll see the term home page often. think of a home page as the starting point of a website. like the table of contents of a book or magazine, the home page usually provides an overview of what youll find at the website. a site can have one page, many pages or a few long ones, depending on how its designed. if there isnt a lot of information, the home page may be the only page. but usually you will find at least a few other pages. web pages vary wildly in design and content, but most use a traditional magaz