科目: 來源:山東省高考真題 題型:閱讀理解
Batteries can power anything from small sensors to large systems. While scientists are finding ways to
make them smaller but even more powerful, problems can arise when these batteries are much larger and
heavier than the devices themselves. University of Missouri(MU) researchers are developing a nuclear energy
source that is smaller, lighter and more efficient.
"To provide enough power, we need certain methods with high energy density (密度)", said Jae Kwon,
assistant professor of electrical and computer engineering at MU. "The radioisotope (放射性同位素) battery
can provide power density that is much higher than chemical batteries."
Kwon and his research team have been working on building a small nuclear battery, presently the size and
thickness of a penny, intended to power various micro / nanoelectromechanreal systems (M/NEMS). Although
nuclear batteries can cause concerns, Kwon said they are safe.
"People hear the word 'nuclear' and think of something very dangerous," he said, "However, nuclear power
sources have already been safely powering a variety of devices, such as pace-makers, space satellites and
underwater systems."
His new idea is not only in the battery's size, but also in its semiconductor (半導(dǎo)體). Kwon's battery uses
a liquid semiconductor rather than a solid semiconductor.
"The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy
can damage the lattice structure (晶體結(jié)構(gòu)) of the solid semiconductor," Kwon said, "By using a liquid semicon
ductor, we believe we can minimize that problem."
Together with J. David Robertson, chemistry professor and associate director of the MU Research Reactor,
Kwon is working to build and test the battery. In the future, they hope to increase the battery's power, shrink
its size and try with various other materials. Kwon said that battery could be thinner than the thickness of
human hair.
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科目: 來源:山東省高考真題 題型:閱讀理解
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科目: 來源:重慶市高考真題 題型:閱讀理解
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科目: 來源:北京高考真題 題型:閱讀理解
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科目: 來源:安徽省高考真題 題型:閱讀理解
閱讀理解。 | ||
Have you ever wondered?
| ||
1. What information can we get from the first passage? | ||
[ ] | ||
A. It is the jet stream that affects how fast airplanes fly. B. Planes go slower when they are moving with the wind. C. It takes more time to fly from NY to London than from London to NY. D. The jet stream always blows from the east to the west across the Atlantic. | ||
2. The word "shoot" underlined in the 2nd passage probably means "_____". | ||
[ ] | ||
A. send for B. move quickly C. come out D. grow quickly | ||
3. It can be inferred that without gravity _____. | ||
[ ] | ||
A. buildings and other structures would float away B. trees and buildings would not so easily fly off C. something around your head would not float away D. everything outside buildings would fly off into space | ||
4. Where can we most probably read this text? | ||
[ ] | ||
A. In a research paper. B. In a short story. C. In a travel magazine. D. In a student's book |
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科目: 來源:湖南省高考真題 題型:閱讀理解
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科目: 來源:江蘇高考真題 題型:閱讀理解
任務(wù)型閱讀。請認真閱讀下列短文,并根據(jù)所讀內(nèi)容在文章后表格中的空格里填入一個最恰當?shù)膯卧~。注意:請將答案寫在相應(yīng)題號的橫線上。每個空格只填1個單詞。 | |||||||||||
For more than twenty years scientists have been seeking to understand the mystery of the "sixth sense" of direction. By trying out ideas and solving problems one by one, they are now getting closer to one answer. One funny idea is that animals might have a built-in compass (指南針). Our earth itself is a big magnet (磁體). So a little magnetic needle that swings freely lines itself with the big earth magnet to point north and south. When people discovered that idea about a thousand years ago and invented the compass,it allowed sailors to navigate (航海) on ocean voyages, even under cloudy skies. Actually the idea of the living compass came just from observing animals in nature. Many birds migrate twice a year between their summer homes and winter homes. Some of them fly for thousands of kilometers and mostly at night. Experiments have shown that some birds can recognize star patterns. But they can keep on course even under cloudy skies. How can they do that? A common bird that does not migrate but is great at finding its way home is the homing pigeon. Not all pigeons can find their way home. Those that can are very good at it, and they have been widely studied. One interesting experiment was to attach little magnets to the birds' heads to block their magnetic sense-just as a loud radio can keep you from hearing a call to dinner. On sunny days, that did not fool the pigeons. Evidently they can use the sun to tell which way they are going. But on cloudy days,the pigeons with magnets could not find their way. It was as if the magnets had blocked their magnetic sense. Similar experiments with the same kind of results were done with honeybees. These insects also seem to have a special sense of direction. In spite of the experiments,the idea of an animal compass seemed pretty extraordinary. How would an animal get the magnetic stuff for a compass. An answer came from an unexpected source. A scientist was studying bacteria that live in the mud of ponds and marshes. He found accidentally little rod-like bacteria that all swam together in one direction-north. Further study showed that each little bacterium had a chain of dense particles inside,which proved magnetic. The bacteria had made themselves into little magnets that could line up with the earth's magnet. The big news was that a living thing,even a simple bacterium, can make magnetite. That led to a search to see whether animals might have it.. By using a special instrument called magnetometer, scientists were able to find magnetite in bees and birds, and even in fish. In each animal,except for the bee. The magnetic stuff was always in or closer to the brain. Thus the idea of a built-in animal compass began to seem reasonable. | |||||||||||
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科目: 來源:遼寧省高考真題 題型:完形填空
完形填空。 | ||||
When I first entered university, my aunt, who is an English professor, gave me s new English dictionary. I was 1 to see that it was an English dictionary, also known as a monolingual dictionary. 2 it was a dictionary intended for non-native learners, none of my classmates had one 3 , to be honest, I found it extremely 4 to use at first. I would look up words in the dictionary and 5 not fully understand the meaning, I was used to the 6 bilingual dictionaries, in which the words are 7 both in English and Chinese, I really wondered why my aunt 8 to make things so difficult for me. Now, after studying English at university for three years, I 9 that monolingual dictionaries are 10 in learning a foreign language. As I found out, there is 11 often NO perfect equivalence (對應(yīng)) between two 12 in two language. My aunt even goes so far as to 13 that a Chinese "equivalent" can never give you the 14 meaning of a word in English! 15 , she insisted that I read the definition (定義) of a world in a monolingual dictionary 16 I wanted to get a better understanding of its meaning. 17 , I have come to see what she meant. Using a monolingual dictionary for learners has helped me in another important way. This dictionary uses a(n) 18 number of words, around 2, 000, in its definitions. When I read these definitions, I am 19 exposed to (接觸) the basic words and learn how they are used to explain objects and ideas. 20 this, I can express myself more easily in English. | ||||
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科目: 來源:遼寧省高考真題 題型:閱讀理解
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