2017年雅思考试备考提分练习
只有知识才是力量,只有知识能使我们诚实地爱人,尊重人的劳动,由衷地赞赏无间断的伟大劳动的美好成果;只有知识才能使我们成为具有坚强精神的、诚实的、有理性的人。以下是小编为大家搜索整理的2017年雅思考试备考提分练习,希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网!
Rogue theory of smell gets a boost
1. A controversial theory of how we smell, which claims that our fine sense of odour depends on quantum mechanics, has been given the thumbs up by a team of physicists.
2. Calculations by researchers at University College London (UCL) show that the idea that we smell odour molecules by sensing their molecular vibrations makes sense in terms of the physics involved.
3. That’s still some way from proving that the theory, proposed in the mid-1990s by biophysicist Luca Turin, is correct. But it should make other scientists take the idea more seriously.
4. “This is a big step forward,” says Turin, who has now set up his own perfume company Flexitral in Virginia. He says that since he published his theory, “it has been ignored rather than criticized.”
5. Most scientists have assumed that our sense of smell depends on receptors in the nose detecting the shape of incoming molecules, which triggers a signal to the brain. This molecular ’lock and key’ process is thought to lie behind a wide range of the body’s detection systems: it is how some parts of the immune system recognise invaders, for example, and how the tongue recognizes some tastes.
6. But Turin argued that smell doesn’t seem to fit this picture very well. Molecules that look almost identical can smell very different — such as alcohols, which smell like spirits, and thiols, which smell like rotten eggs. And molecules with very different structures can smell similar. Most strikingly, some molecules can smell different — to animals, if not necessarily to humans — simply because they contain different isotopes (atoms that are chemically identical but have a different mass)。
7. Turin’s explanation for these smelly facts invokes the idea that the smell signal in olfactory receptor proteins is triggered not by an odour molecule’s shape, but by its vibrations, which can enourage an electron to jump between two parts of the receptor in a quantum-mechanical process called tunnelling. This electron movement could initiate the smell signal being sent to the brain.
8. This would explain why isotopes can smell different: their vibration frequencies are changed if the atoms are heavier. Turin’s mechanism, says Marshall Stoneham of the UCL team, is more like swipe-card identification than a key fitting a lock.
9. Vibration-assisted electron tunnelling can undoubtedly occur — it is used in an experimental technique for measuring molecular vibrations. “The question is whether this is possible in the nose,” says Stoneham’s colleague, Andrew Horsfield.
10. Stoneham says that when he first heard about Turin’s idea, while Turin was himself based at UCL, “I didn’t believe it”。 But, he adds, “because it was an interesting idea, I thought I should prove it couldn’t work. I did some simple calculations, and only then began to feel Luca could be right.” Now Stoneham and his co-workers have done the job more thoroughly, in a paper soon to be published in Physical Review Letters.
11. The UCL team calculated the rates of electron hopping in a nose receptor that has an odorant molecule bound to it. This rate depends on various properties of the biomolecular system that are not known, but the researchers could estimate these parameters based on typical values for molecules of this sort.
12. The key issue is whether the hopping rate with the odorant in place is significantly greater than that without it. The calculations show that it is — which means that odour identification in this way seems theoretically possible.
13. But Horsfield stresses that that’s different from a proof of Turin’s idea. “So far things look plausible, but we need proper experimental verification. We’re beginning to think about what experiments could be performed.”
14. Meanwhile, Turin is pressing ahead with his hypothesis. “At Flexitral we have been designing odorants exclusively on the basis of their computed vibrations,” he says. “Our success rate at odorant discovery is two orders of magnitude better than the competition.” At the very least, he is putting his money where his nose is.
Questions 1-4
Do the following statements agree with the information given in the passage? Please write
TRUE if the statement agrees with the writer
FALSE if the statement does not agree with the writer
NOT GIVEN if there is no information about this in the passage
1. The result of the study at UCL agrees with Turin’s theory.
2. The study at UCL could conclusively prove what Luca Turin has hypothesized.
3. Turin left his post at UCL and started his own business because his theory was ignored.
4. The molecules of alcohols and those of thiols look alike.
Questions 5-9
Complete the sentences below with words from the passage. Use NO MORE THAN THREE WORDS for each answer.
5. The hypothesis that we smell by sensing the molecular vibration was made by ______.
6. Turin’s company is based in ______.
7. Most scientists believed that our nose works in the same way as our ______.
8. Different isotopes can smell different when ______ weigh differently.
9. According to Audrew Horsfield, it is still to be proved that ______ could really occur in human nose.
Question 10-12
Answer the questions below using NO MORE THAN THREE WORDS from the passage for each answer.
10. What’s the name of the researcher who collaborated with Stoneham?
11. What is the next step of the UCL team’s study?
12. What is the theoretical basis in designing odorants in Turin’s company?
Answer Keys and Explanations1. T 见第一段。“give sth the thumbs up”为“接受“的意思。
2. F 见第三段。 “That’s still some way from proving that the theory, proposed in the mid- 1990s by biophysicist Luca Turin, is correct.”意即“现在尚无法证实生物物理学家Luca在九十年代中期提出的`理论是否正确。”
3. NG
4. T 见第六段 “Molecules that look almost identical can smell very different — such as alcohols, which smell like spirits, and thiols, which smell like rotten eggs.”“identical” 一词是“完全相同”的意思。这句话是说alcohols和thiols的分子结构看起来一样,但是它们的味道却相去甚远。
5. Luca Turin 文章第二,三和七段均可看出Luca的理论即人类的鼻子是通过感觉气味分子的震动来分辨气味的。
6. Virginia 见第四段。
7. tongue 见第五段 “This molecular ’lock and key’ process is thought to lie behind a wide range of the body’s detection systems: it is how some parts of the immune system recognise invaders, for example, and how the tongue recognizes some tastes.”
8. the atoms 见第八段 “This would explain why isotopes can smell different: their vibration frequencies are changed if the atoms are heavier.”
9. vibration-assisted electron tunneling 见第九段 ““The question is whether this is possible in the nose,” says Stoneham’s colleague, Andrew Horsfield.” 句中的代词“this”指句首的“vibration-assisted electron tunneling”。
10. Andrew Horsfield 见第九段结尾。
er experimental verification 见第十三段。
r computed vibrations 见第十四段
-
秋天作文范文(通用20篇)
在学习、工作或生活中,说到作文,大家肯定都不陌生吧,作文是人们以书面形式表情达意的言语活动。你知道作文怎样才能写的好吗?下面是小编精心整理的秋天作文,仅供参考,大家一起来看看吧。秋天作文篇1我爱秋天,秋天教人以万物般的金黄。我在秋风中漫步,放眼那金子般的世...
-
2015年雅思报考指南:雅思考试内容
雅思考试(IELTS-InternationalEnglishLanguageTestingSystem,国际英语语言测试系统)是一种较全面地针对听说读写四项能力的、为打算到英语国家学习、工作或定居的人们设置的英语水平考试。雅思考试由剑桥大学考试委员会外语考试部、英国文化协会及IDP教育集团所...
-
雅思多少分才算高分
雅思考试多少分算高分是相对的,要看你选择的学校录取的分数也不同,每个地方的平均水平也不同,以下是小编为大家搜索整理的雅思多少分算高分,希望对正在关注的您有所帮助!雅思多少分算高分一般来说雅思成绩达到6.5分以上就算是高分了。雅思总分是9分,一般出国留学的...
-
2017年雅思口语练习试题
雅思考试也受到诸多亚洲国家的认可,例如:马来西亚、新加坡等,并且是欧洲(例如:荷兰、瑞典、芬兰等国家)众多院校英语授课项目首选的英语语言能力证明。yjbys小编收集一些雅思口语练习试题,希望大家认真阅读!ColorsWhatisyourfavoritecolor?Doyouusuallywearthiscolo...