Alpha particles directly come from__________. 查看材料
A.decaying uranium
B.decaying radon atoms
C.air from the ground
D.radiation particles
第1题
阅读材料,回答题。
Alpha Particle
From decaying radon ( 氡) atoms can destroy the living cells they strike and increase the likelihood that those cells will later become cancerous.Researchers have now directly demonstrated that neighboring cells not suffering direct hits can be harmed, too. They"ve also taken a step toward showing how this type of radiation,called alpha particles, indirectly hurts those bystanders.
Radon derives from the decay of uranium ( 铀) and seeps naturally into the air from the ground.lt"s the primary environmental source of alpha particles, which contribute to cancer risk by causing aberrations (失常)in DNA.Alpha particles from inhaled radon are second only to smoking as a cause of lung cancer.
Because a person"s exposure to alpha particles typically is low, researchers have had to estimate public health threats from radon by guess from the effects of higher doses of alpha radiation.Such data comes primarily from studies of survivors of the atomic bombs that destroyed Hiroshima and Nagasaki in Japan. The customary extrapolation ( 推测 ) assumes that cancer risk is proportional to the dose of radiation even at low doses.
Radiation"s effects in cell structure don"t necessarily reflect what happens in "a whole organism, with its full range of defense repair mechanisms, " says Duport.Processes such as DNA repair and cell death triggered by radiation damage could cancel the effect on by stander cells observed in the lab, he suggests.
Furthermore, while a bystander effect can contribute to cancer, other cell-to-cell interactions in living tissue "may relieve increased risk." says Barry Michael, a radiation biophysicist at the Gray Cancer Institute in Northwood, England.One of these interactions halts cell division and hence cancer. "The jury is still out on whether cell-to-cell effects lead to a greater or lower risk, " Michael says.
The passage‘s main topic is__________. 查看材料
A.The experiment done by researchers
B.Uranium is the key killer of neighboring cells
C.Cell-to-cell interaction can make up for the hurt cells
D.Bystander cells can be indirectly damaged by alpha particles
第2题
看材料
A.doctors will be able to repair the destroyed cells of human bodies
B.cancer and other infected diseases will be cured
C.there will be more accurate diagnoses of diseases
D.the medical devices will become smaller and devices with single function are produced
第3题
查看材料
A.tiny
B.lighter
C.costly
D.diversified
第4题
查看材料
A.Nanotechnology will be used to change the structures of materials.
B.Nanotechnology will make an operation more precisely.
C.Nanotechnology will change the properties of materials.
D.Nanotechnology will cure diseases that can"t be solved at present.
第5题
阅读材料,回答题。
Nanotechnology
Many of the grand challenges of today and the future are found in the question: "How are we going to solve the problems and make serious improvements in industrial manufacturing, disease control, environmental pollution control, global climate change, food production, transportation, communication, and others?"
Nanotechnology ( 纳米技术 ) promises to make revolutionary contributions.Within the next few years we can expect to see major improvements. Here are some possibilities the things to come.Nanotechnology is fundamentally changing the way materials and devices will be produced in the future.
Nanostructures, ceramics, polymers, metals, and other materials will have greatly improved mechanical properties.In fact, with the ability to build things atom-by-atom and molecule-by-molecule there will be new classes of structural materials.Nanotechnology will enable products to be lighter, stronger, smarter, cheaper,cleaner, and more precise.
The ability to synthesize nanoscale budding blocks with precisely controlled size and composition and then to assemble them into larger structures with unique properties and functions will revolutionize segments of the materials manufacturing industry. Nanotechnology is expected to bring about lighter, stronger, and programmable materials ; reductions in life-cycle costs through lower failure rates; innovative devices based on new principles and architectures ; and use of molecular cluster manufacturing.
Nanotechnology will provide new tools for medicine.It could radically change the way surgery is done.It will make it possible to do molecular scale surgery to repair and rearrange cells.Since disease is the result of physical disorder, misarranged molecules and cells, medicine at this level should be able to cure most diseases.
Mutations in DNA could be repaired and cancer cells, toxic chemicals, and viruses could be destroyed through use of medical Nan devices.
Nanotechnology enabled increases in computational power will permit the characterization of macromolecular networks in realistic environments.Such simulations will be essential elements in the development of biocompatible implants and in the drug discovery process. Nanotechnology has the potential to significantly impact energy efficiency, storage, and production, Nanotechnology can change the economics of energy production.
The passage deals mainly with__________. 查看材料
A.grand challenge in manufacturing, medicine and computer industry
B.possibilities of nanotechnology"s contributions in the future
C.great changes caused by nanotechnology
D.practical application of nanotechnology
第6题
料
A.books
B.lecture
C.tricks
D.fact
E.memory
F.list
第7题
Paragraph 5__________. 查看材料
A.Good results
B.An ancient skill
C.Gaining attention
D.Memory tricks
E.A lecture on memory techniques
F.Ways to improve memory
第8题
Paragraph 4__________. 查看材料
A.Good results
B.An ancient skill
C.Gaining attention
D.Memory tricks
E.A lecture on memory techniques
F.Ways to improve memory
第9题
Paragraph 3__________. 查看材料
A.Good results
B.An ancient skill
C.Gaining attention
D.Memory tricks
E.A lecture on memory techniques
F.Ways to improve memory
第10题
根据材料,完成题。
Memory Test
1. "I am going to give you five techniques that will enable you to remember anything you need to know at school, " promised lecturer an Robinson to a hundred school children. He slapped his hand down on the table. "When I&39;ve finished in two hours&39;time, your work will be far more effective and productive. Anyone not interested, leave now." The entire room sat still.
2. Robinson calls himself the Mind Magician ( 魔术师 ) .He specializes in doing magic tricks that look totally impossible, and then he reveals that they involve nothing more mysterious than good old-fashioned trickery ( 骗术 ) . "l have always been interested in tricks involving memory being able to reel off ( 一口气说出) the order of cards in a pack, that sort of thing." he explains.
3. Robinson was already lecturing to schools on his magic techniques when it struck him that students might find memory techniques even more valuable. "It wasn&39;t difficult area to move into, as the stuff&39;s all there in books." So he summarized everything to make a two-hour lecture about five techniques.
4. "You want to learn a list of a hundred things? A thousand? No problem, " says Robinson. The scandal is that every child is not taught the techniques from the beginning of their school life. The schoolchildren who were watching him thought it was brilliant. "I wish I&39;d been told this earlier, " commented Mark, after Robinson had shown them how to construct "mental journeys" .
5. Essentially, you visualize (想象) a walk down a street, or a trip round a room, and pick the points where you will put the things you want to remember the lamppost, the fruit bowl. Then in each location you put a visual representation of your list-phrasal verbs, historical dates, whatever making them as strange as possible.It is that simple, and it works.
6. The reaction of schools has been uniformly enthusiastic. "The pupils benefited enormously from his presentation, " says Dr. Johnston, head of the school where Robinson was speaking. "ideally we should run a regular class in memory techniques so pupils can pick it up gradually."
Paragraph 2__________. 查看材料
A.Good results
B.An ancient skill
C.Gaining attention
D.Memory tricks
E.A lecture on memory techniques
F.Ways to improve memory
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