日期：2009-10-29 Novell's Net ware has become the strongest competitor to IBM's own network operating environment and predates IBM in its support for LANs. In fact,IBM now markets Net ware for both the PC Network and for Token Ring in addition to its own software.Th... 阅读全文>>

日期：2009-10-29 Many networks are managed by a computer called a file server.A file server has a large－capacity hard disk and special software that manages access to flies on the network. It controls how data and database are shared among users on the network and... 阅读全文>>

日期：2009-10-29 There are two categories of networks: local area networks (LANs) and wide area networks (WANs). Here I'd like to mainly talk about LAN. A LAN is a system of computers and associated peripherals such as Printers that are physically connected by cable... 阅读全文>>

日期：2009-10-28 Digital television is based on the idea of recording information in a digital, rather than an analogue format（模拟形式）. The idea is to reduce the information to a series of electronic signals, which can be written in a code of 0's and 1's. This b... 阅读全文>>

日期：2009-10-28 Astronomers can tell just how hot the surface of the moon gets. The side of the moon toward the sun gets two degrees hotter than boiling water. The night side reaches 243 degrees below zero. In an eclipse, the earth's shadow falls on the moon. Then... 阅读全文>>

日期：2009-10-28 Strange things happen to time when you travel, because the earth is divided into twenty-four time zones, one hour apart.You can have days with more or fewer than twenty-four hours, and weeks with more or fewer than seven days. If you make a five-day... 阅读全文>>

日期：2009-10-28 When is a horse a pony? Horses are measured in hands：one hand equals 4 inches.The height of a horse is measured from the ground to the highest point of the withers(the part of a horse's back between its shoulder blades). Any horse under 14 hands 2... 阅读全文>>

日期：2009-10-28 Fingers were made before forks.When a person gives up good manners, puts aside knife and fork, and dives into his food, someone is likely to repeat that saying. The fork was an ancient agricultural tool, but for centuries no one thought of eating wi... 阅读全文>>

日期：2009-10-28 The air-cushioned vehicle is not an airplane, since it does not have wings.It is neither a ship nor an automobile, since it travels clear of sea and land.It has a conventional gasoline engine, but no wheels.How does it travel?What keeps it in the ai... 阅读全文>>

日期：2009-10-28 An electric switch is often on a wall near the door of a room. Two wires lead to the lamp in the room. The switch is fixed in one of them. The switch can cause a break in this wire, and then the light goes. The switch can also join the two parts of... 阅读全文>>

日期：2009-10-28 Los Alamos National Laboratory scientists are using a new technique to see fingerprints on surfaces that typically make them invisible. The method uses a technology called mini- X-ray fluorescence（X射线荧光光谱仪） to detect chemical elements in fi... 阅读全文>>

日期：2009-10-28 The latest generation of these ever-smarter garments look like ordinary clothes, assembled together with Velcro that conducts electricity, these pieces form a bag that looks, feels, and weighs like your typical leather purse. 最新型的可穿着电脑产品... 阅读全文>>

日期：2009-10-28 If winning is everything, British anthropologists（人类学家） have some advice: Wear red. Their survey of four sports at the 2004 Olympic Games in Athens shows competitors were more likely to win their contests if they wore red uniforms or red body... 阅读全文>>

日期：2009-10-28 The first true piece of sports equipment that man invented was the ball. In ancient Egypt, as everywhere, pitching stones was a favorite children's game. But a badly thrown rock could hurt a child. Looking for something less dangerous to throw, the... 阅读全文>>

日期：2009-10-28 Man's first real invention, and one of the most important inventions in history, was the wheel.All transportation and every machine in the world depend on it. The wheel is the simplest yet perhaps the most remarkable of all inventions, because there... 阅读全文>>

日期：2009-10-28 Researchers determined that the specimens are around 195,000 years old. 对化石的深入分析使现代人的历史可以追溯到19.5万年以前。 A new analysis of bones unearthed（采掘出的） nearly 40 years ago in Ethiopia has pushed the fossil record of modern human... 阅读全文>>

日期：2008-11-20 Of the tens of thousands of ships on the ocean bottom, only a handful, less than 1 percent, contain negotiable treasure, such as gold and jewels. Most give us a different priceless treasure -- history. A sunken ship lies in trust, preserved in the a... 阅读全文>>

日期：2008-01-23 Weighing too much can damage your health, and obesity is a growing problem for both kids and adults around the world. Sleep might be one answer to the problem. A new study has found that elementary school students who slept too little were more like... 阅读全文>>

日期：2008-01-23 Jan.16,2008 It can be hard to know what newborns want. They can't talk, walk, or even point at what they're thinking about. Yet babies begin to develop language skills long before they begin speaking, according to recent research. And, compared to a... 阅读全文>>

日期：2008-01-23 Most schools ban chewing gum, but in a few years they might consider changing that rule. Why? Scientists are finding evidence that gum chewing may be good for your health. It may even help boost your test scores. This exciting research is just beginn... 阅读全文>>