2. 外语
  3. Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why th

Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why th

admin2013-03-11  58
问题     Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why the artificial odor detectors that engineers have been building since the 1950’s to try to mimic the olfactory(嗅觉的) abilities of our built-in sensors have taken so long to find their way to the market--and then, in most cases, have flopped(失败).
    But things are finally looking up for the electronic nose. Thanks to advances in chip technology and pattern-recognition techniques, increasingly tiny sniffers (嗅探器) are beginning to live up to their moniker (模仿者)- Today e-noses are being tested for everything from disease detection to disaster prevention, and lower-prices models are starting to come to the market including an $ 8,000 device called the Cyranose 320 being introduced this week by Cyrano Sciences of Pasadena, Calif.
    Like our proboscises(长鼻子), e-noses are only as good as their sensors, and all of them operate on oiliness(油质)--rather than to the molecule itself. Working together, the receptors can generate unique principles remarkably similar to those of a real nose. Humans detect odors with up to 650 types of receptors found on cells high up in the nasal passages, somewhere between our eyebrows. How the nose works is still something of a mystery, but it is believed that each receptor responds to a subtle characteristic of a molecule that carries odor--its peculiar shape, say, or degree of "smell prints" of a wide variety of odors, which are then parceled off to the brain and stored.
    In e-noses, chemical sensors replace the body’s cellular receptors, and microprocessors substitute for the brain. "What limits these devices is how well the sensors are doing," explains Nathan Lewis, the Caltech chemist who helped invent the sensor technology licensed by Cyrano and who has since continued his research independently. He compares the power of e-noses to the resolution of computer monitors: "Are you seeing the world in eight shades of gray or in 16 million colors?"
Which of the following is closest in meaning to the phrase "looking up" (Line 1, Para. 2)?
选项 A、Raising one’s eyes.
B、Turning better.
C、Searching for.
D、Paying a visit.
答案B
解析 语义题。该题测的是对常见短语look up在特定的语境中的准确理解。此处的意思是“有所改善”，正确答案是B。
转载请注明原文地址:https://kaotiyun.com/show/FBr7777K
0

大学英语四级

相关试题推荐
随机试题
最新回复(0)