题目内容
Superconducting Ceramic (陶瓷)
An underground revolution begins this winter. With the flip (轻击) of a switch, 30,000 homes in one part of Detroit will soon become the first in the country to receive electricity transmitted by ice-cold high-performance cables. Other American cities are expected to follow Detroit's example in the years ahead, which could conserve enormous amounts of power.
The new electrical cables at the Frisbie power station in Detroit are revolutionary because they are made of superconductors. A superconductor is a material that transmits electricity with little or no resistance. Resistance is the degree to which a substance resists electric current. All common electrical conductors have a certain amount of electrical resistance. They convert at least some of the electrical energy passing through them into waste heat. Superconductors don't. No one understands how superconductivity works. It just does.
Making superconductors isn't easy. A superconducting material has to be cooled to an extremely low temperature to lose its resistance. The first superconductors, made more than 50 years ago, had to be cooled to -263 degrees Celsius before they lost their resistance. Newer superconducting materials lose their resistance at -143 degrees Celsius.
The superconductors cable installed at the Frisbie station is made of a ceramic material that contains copper, oxygen, bismuth (铋), strontium (锶), and calcium (钙). A ceramic is a hard, strong compound made from clay or minerals. The superconducting ceramic has been fashioned into a tape that is wrapped lengthwise around a long tube filled with liquid nitrogen. Liquid nitrogen is supercold and lowers the temperature of the ceramic tape to the point where it conveys electricity with zero resistance.
The United States loses an enormous amount of electricity each year to resistance. Because cooled superconductors have no resistance, they waste much less power. Other cities are watching the Frisbie experiment in the hope that they might switch to superconducting cable and conserve power, too.
What is the benefit of the revolution mentioned in the first paragraph？
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Science and Truth
"FINAGLE" (欺骗) is not a word that most people associate with science. One reason is that the image of the scientist is of one who always(51) data in an impartial (不偏不倚的) search for truth~ In any debate --(52) intelligence, schooling, energy -- the phrase "science says" usually disarms opposition.
But scientists have long acknowledged the existence of a "finagle factor" -- a tendency by many scientists to give a helpful change to the data to(53)desired results. The latest of the finagle factor in action comes from Stephen Jay Gould, a Harvard biologist, who has(54) the important 19th century work of Dr. Samuel George Morton. Morton was famous in his time for analysing the brain(55) of the skulls as a measure of intelligence. He concluded that whites had the largest brains, that the brains of Indians and blacks were smaller, and(56) , that whites constitute a superior race.
Gould went back to Morton's original data and concluded that the(57)were an example of the finagle at work. He found that Morton's "discovery" was made by leaving out embarrassing data,(58) incorrect procedures, and changing his criteria -- again, always in favour of his argument. Morton has been thoroughly discredited by now and scientists do not believe that brain size reflects(59) .
But Gould went on to say Morton's story is only an example of a common problem in(60) work. Some of the leading figures in science are(61) to have used the finagle factor. Gould says that Isaac Newton fudged out (捏造) to support at least three central statements that he could not prove. And so(62)Laudius Ptolemy, the Greek astronomer, whose master work, Almagest, summed up the case for a solar system that had the earth as its centre. Recent(63)indicate that Ptolemy either faked some key data or resorted heavily to the finagle factor.
All this is important because the finagle factor is still at work. For example, in the artificial sweetener controversy, for example, it is(64) that all the studies sponsored by the sugar industry find that the artificial sweetener is unsafe,(65) all the studies sponsored by the diet food industry find nothing wrong with it.
Plants in Desert
Only special plants can survive the terrible climate of a desert, for these are regions where the annual range of the soil temperature can be over 75℃. Furthermore, during the summer there are few clouds in the sky to protect plants from the sun's ray. Another problem is the fact that there are frequently strong winds which drive small, sharp particles of sand into the plants, tearing and damaging them. The most difficult problem for all forms of plant life, however, is the fact that the entire annual rainfall occurs during a few days or weeks in spring.
Grasses and flowers in desert survive from one year to the next by existing through the long, hot, dry season in the form. of seeds. These seeds remain inactive unless the right amount of rain falls. If no rain falls, or if insufficient rain falls, they wait until the next year, or even still the next. Another factor that helps these plants to survive is the fact that their life cycles are short. By the time that the water from the spring rains disappears—just a few weeks after it falls—such plants no longer need any.
The perennials have special features which enable them to survive as plants for several years. Thus, nearly all desert perennials have extensive root systems below ground and a small shoot system above ground. The large root network enables the plant to absorb as much water as possible in a short time. The small shoot system, on the other hand, considerably limits water loss by evaporation.
Another feature of many desert perennials is that after the rainy season they lose their leaves in preparation for the long, dry season, just as trees in wetter climates lose theirs in preparation for the winter. This reduces their water loss by evaporation during the dry season. Then, in next rainy season, they come fully alive once more, and grow new branches, leaves and flowers, just as the grasses and flowers in desert do.
Ordinary plants are unable to survive in the desert mainly because of the changeable weather.
钢铁冶炼排放的主要大气污染物有()。
确定卫生防护距离计算系数时，工业企业大气污染源构成分类不正确的是（)。A．工业企业大气污染源确定卫生防护距离计算系数时，工业企业大气污染源构成分类不正确的是()。
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