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英语是考研初试当中比较拉分的科目,历来令不少考生又爱又恨。许多考生的英语都有很大的进步空间,因此英语该如何学就成为了众多考生关心的重点。想要学好英语,实战经验很重要。下面,帮考网为大家带来考研初试英语科目的一些模拟试题,正在备考的小伙伴赶紧练起来吧。
Many people think that information technology and biotechnology will rule the 21st century. Robert Birge, a chemist at the University of Connecticut, is trying to combine them, by making computer memories out of protein.
The protein in question is bacteriorhodopsin (bR), a molecule that undergoes a structural change when it absorbs light. By using genetic engineering to tweak wild bR from a bacterium called Halobacterium salinarum, Dr Birge and his colleagues have made a variety of the molecule that they claim is well-suited to act as an element of a computer\'s memory. Hit with a green light, it adopts one shape. Hit subsequently with a red light, it twists itself into another. Then, if hit with blue light, it resets itself into its original state.
To make a memory from the protein, Dr Birge suspends elements made from it in a transparent plastic cube known as a cuvette. A pair of lasers arranged at right angles to one another write data into the cuvette by shining in turn on “slices” through the plastic matrix. The first laser, which produces green light, sweeps the whole cuvette, causing its protein contents to take on a shape that (in binary code) is designated as “zero”。 The second laser, which produces red light, then stimulates particular sites to take the second shape. This corresponds to “one” in binary code. Once the lasers are switched off, data recorded this way will, according to Dr Birge, remain stable for more than 12 years.
To read the stored data, a low-powered red laser is shone slice by slice through the cuvette. This does not disturb the conformation of the protein molecules; but those in state “zero” absorb light at this wavelength. A machine placed behind the cuvette detects this absorption pattern and translates it into the appropriate string of ones and zeroes. Once the contents have been read into a more conventional storage device, the cuvette can be wiped clean and reset by illuminating it with a blue laser.
Dr Birge says that each cuvette can now hold about seven gigabytes of data (a small laptop computer might have about this much space on its hard drive)。 He hopes to boost that figure to ten gigabytes by finding a better-performing variety of the protein. Only those with deep pockets, however, could afford the $25,000 cost of each device.
Luckily for Dr Birge, the deep-pocketed American air force thinks that bR cuvettes could be a good way to equip its aircraft and satellites with light, high-density devices to store the mountains of images collected during reconnaissance missions. A protein-based memory is particularly suitable for this, because the bR molecule is robust enough to withstand the barrage of radiation from space that wreaks havoc on conventional magnetic-memory devices operating at high altitude.
注(1):本文选自Economist; 12/22/2001, p94, 1/2p, 1c;
注(2):本文习题命题模仿对象2001年真题Text 3(第一题到第三题); 2004年真题Text 1(第四题和第五题);
1. What is the passage mainly about?
[A]What will rule the 21st century.
[B]How bacterial protein can be used in computers.
[C]What we can get from bacterial protein.
[D]How to make bacterial protein.
2. The application of bR turns out to be___________.
[A]very trustworthy
[B]rather superficial
[C]somewhat contradictory
[D]quite encouraging
3. The basic problem of applying bR to computer lies in ____________.
[A]limited space on hard drive
[B]its complexity
[C]its high price
[D]its limited users
4. Which of the following is not the advantage of bR?
[A]Working at higher altitude.
[B]Light weight.
[C]High density.
[D]Safe from strong radiation.
5. Which of the following is true according to the text?
[A]bR has a wide variety of application in life.
[B]The protein molecules have stable characteristics.
[C]The data recorded with bR can be kept for a long time.
[D]The new device will replace conventional storage device.
答案:BDCAC
以上就是帮考网为大家带来的全部内容,希望能给大家一些帮助。帮考网提醒:在最后阶段,调整自己的心态也是非常重要的,每年都有考生临考前放弃,所以小伙伴们要注意不要给自己太大的压力哦。另外,小伙伴们如果还有其他关于考研信息的疑问,也可以留言咨询哦。
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