科目: 來源:同步題 題型:閱讀理解
A new study has found no evidence that sunscreen, commonly used to reduce the
risk of skin cancer, actually increases the risk.
Researchers from the Umversity of Iowa based their findings on a revicw of 18 earlier
studies that looked at the association between sunscreen use and melanoma(黑素瘤 ).
They said that they found flaws in studies that had reported associations between sunscreen
use and higher risk of melanoma.
Most health experts believe that by protecting the skin from the harmful effects of
the sun, sunscreen helps prevent skin cancer, which is increasing in incidence (發(fā)生率)
faster than any other cancer in the United States.
But questions have been raised about sunscreen and whether it may have the opposite
effect, perhaps by allowing people to remain exposed to the sun longer without burning.
The researchers said that among the problems with some earlier studies is that they
often failed to take into account that those people most at risk for skin cancer-people
with fair skin and freckles(雀斑) ,for example-are more likely to use sunscreen. As a
result , it may appear that sunscreen users get cancer more often.
The studies , which generally relied on volunteers to recall their sunscreen use,were
also unable to prove how well the products had been applied , Said the new study.
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科目: 來源:安徽省模擬題 題型:閱讀理解
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(dāng)?shù)膯卧~. 注意:每個空格只填1個單詞. | ||||||||||
People who enjoy a dream-filled sleep are better at recalling information and making links between facts when waking. But recharging with a shallow (小睡) offers no such mental improvement, the research suggests. The results of the study added to the growing body of evidence that Rapid Eye Movement (REM) sleep is very important to the brain's ability to form strong memories. An average night's rest includes four or five spells of REM sleep, but these bursts tend to be lengthier towards the end of the night. This means adults getting less than the recommended seven to eight hours a night -- and therefore inadequate REM sleep -- may be damaging their mind's ability to memorize: Although REM sleep is not classified as a type of deep sleep, it is only reached after the brain has passed through deep sleep stages. In the recent study, participants were shown groups of three words and asked to find another word that can be associated with all three words. They were tested once in the morning and then given the same task again in the afternoon. In between, some were allowed a nap with REM sleep, some a nap without REM sleep, while the others had a quiet rest period. The quiet rest and non-REM sleep groups didn't improve, but the REM sleep group improved on their morning performance by an average of almost 40 per cent. Dr Sara Mednick, a sleep researcher at the University of California who led the study, believes the formation of connections between previously unassociated information in the brain occurs during REM sleep. It is believed that sleep acts as a sort of mental filing system, enabling the brain to sort relevant information from useless information. This process may take place as memories are removed hem one art of the brain to others. | ||||||||||
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科目: 來源:同步題 題型:閱讀理解
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科目: 來源:同步題 題型:閱讀理解
Do you want to live another 100 years or more? Some experts say that scientific advances will one
day enable humans to last tens of years beyond what is now seen as the natural limit of the human life
span.
"I think we are knocking at the door of immortality(永生) , " said Michael Zey, a Montclair State
University business professor and author of two books on the future. "I think by 2075 we will see it and
that's a conservative estimate(保守的估計)."
At the conference in San Francisco, Donald Louria, a professor at New Jersey Medical School in
Newark said advances in using genes as well as nanotechnology(納米技術(shù)) make it likely that humans
will live in the future beyond what has been possible in the past. "There is a great push so that people can
live from 120 to 180 years," he said. "Some have suggested that there is no limit and that people could
live to 200 or 300 or 500 years.
However,many scientists who specialize in ageing are doubtful about it and say the human body is just
not designed to last past about 120 years. Even with healthier lifestyles and less disease,they say the
failure of the brain and organs will finally lead all humans to death.
Scientists also differ on what kind of life the super aged might live. "lt remains to be seen if you pass
120 ,you know; could you be healthy enough to have good quality of life?" said Leonard Poon, director
of the University of Georgia Gerontology Centre. "At present people who could get to that point are not
in good health at all. "
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科目: 來源:同步題 題型:閱讀理解
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科目: 來源:同步題 題型:閱讀理解
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科目: 來源:模擬題 題型:閱讀理解
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科目: 來源:0113 期中題 題型:完形填空
Close test. | ||||
Not long ago, the only time you could see a robot was when you were reading a novel or watching a movie such as Star Wars. Today, 1 a lot of things in science stories have been science facts. Robots are starting to 2 in our everyday lives. These robots have different sizes, shapes and colors. But they all have the same 3 of man-made " 4 ". Leading the robot revolution (革命) are industrial robots that work in factories. Industrial robots can do different kinds of jobs that are often 5 and sometimes dangerous. Robots are also coming to American homes, though not as quickly as they are entering 6 . These robots aren't as friendly and 7 as those you saw in Star Wars. But, their makers say, today's home robots "walk" and sense objects in their own way. They even 8 objects though they may sometimes drop. Well, nobody is 9 . We may 10 home robots today, but some day they may see and hear 11 than humans do. We 12 can only see certain wave lengths of light and hear certain 13 . That's because the 14 of our eyes and ears are 15 . Robots, however, need not have the same limits 16 we have. Robots may also be 17 wit devices (裝置) that 18 information humans can't. However, to understand 19 their sensing devices pick up is a hard job. Remember, man-made brains 20 information, including all kinds of data, as zeroes and ones. Imagine the difficulty in trying to explain to a robot what a football looks like-using only zeroes and ones. | ||||
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科目: 來源:陜西省模擬題 題型:閱讀理解
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科目: 來源:上海高考真題 題型:填空題
Directions: Complete the following passage by using the words in the box. Each word can only be used once. Note that there is one word more than you need. | |
has gone into developing intelligent materials, this may not be as 1_____ as it sounds. Self-cleaning clothes have now been created, and these new materials provide 2_____ resistance to dirt as well as water. As a result, they require much less cleaning than traditional materials. The creation of self-cleaning clothes provides an example of how nature helps scientists develop better products. This self-cleaning nature is known as the "lotus effect". The name comes, of course, from the lotus leaves, which are famous for growing in muddy lakes and rivers while remaining almost 3_____ clean. By observing nature, scientists are 4_____ the qualities of the lotus leaves to the materials they have engineered. Because of this, some remarkable new products have been 5_____. Among them are special windows that are resistant to dirt and water. A special 6_____ on these windows not only prevents dirt from sticking to their surfaces, but also allows dust to be easily washed off by the rain. In fact, these new windows have already been 7_____ to some cars. Even when traveling at high speed through rain, these cars never have to use their windshield wipers (雨刮器). Although we have already seen some practical applications, even more dramatic 8_____ will be made in the future, and they will, perhaps, change our world completely. Undoubtedly, technology is an important development, and it will have an even bigger 9_____ on our lives. |
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