原子（atom)

A.原子

B.原子的

C.微粒

D.微粒的

Which of the following statements is incorrect？

A．Few elements are suitable for use as atomic fuel.

B．An atomic power station can supply the same quantity of energy all the year round.

C．A hydro-electric power station can be built anywhere.

D．Graphite is a non-fissile material.

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m predicted superconductivity. This phenomenon was discovered in 1911 by Onnes while he was studying frozen mercury.

More than 40 years passed before physicists were able to offer an explanation for superconductivity. The accepted theory, developed in the 1950s, holds that the fundamental behavior. of electrons changes at very low temperatures because of the effects of quantum mechanics. Electrons are tiny particles that make up the outer part of an atom, circling rapidly around the nucleus of the atom. In a regular conductor—a metal that conducts an electric current—the outermost electrons are not bound tightly to the atoms, and so they move around relatively freely. The flow of these electrons is an electric current.

At normal temperatures, a conductor's electrons cannot move completely freely through the metal because they are "bumped around" by the metal's atoms. But according to the leading theory of superconductivity, when a metal is very cold, electrons form. pairs. Then, like couples maneuvering on a crowded dance floor but never colliding, the paired electrons are able to move unimpeded through the metal. In pairing up, it seems, the electrons are able to "blend together" and move in unison without resistance. This explanation seems to account for superconductivity at extremely low temperatures, but in 1986 scientists in Switzerland found that some metal-containing ceramics are superconductors at much higher temperatures. By 1992, scientists had developed ceramics that become superconducting at - 297'F, and some researchers speculated that room-temperature superconductors may be possible. Scientists are still trying to formulate a theory for high-temperature superconductivity.

The new ceramic materials can be maintained at their superconducting temperatures, with relatively inexpensive liquid nitrogen rather than the much colder and much more costly liquid helium required by metal superconductors. The cost difference could make superconductivity practical for many new technologies. For example, magnetically levitated trains, which require superconducting electromagnets, would be much cheaper to build than they are now. Superconducting devices might also be used for advanced power transmission lines and in new types of compact, ultrafast computers. But for the time being, superconductivity is finding application mostly in scientific research and in some kinds of medical imaging devices.

The flow of an electric current in a regular conductor is made possible by the fact that______.

A．electrons circle rapidly around the atom

B．the outermost electron move relatively freely around the atom

C．the innermost electrons stick to the atom

D．the outermost electrons are bound tightly to the inner ones

Robert J. Oppenheimer was a famous American physicist, who directed the【1】of the first atomic bombs.

Oppenheimer was born in New York City on April 22, 1904, and was educated at Harvard University and the universities of Cambridge. After【2】the International Education Board from 1928 to 1929, he became a professor of physics at the University of California and the California Institute of Technology, where he built up large【3】of theoretical physics. He was noted for his contributions【4】to the theory of relativity, cosmic rays, and neutron stars.

From 1943 to 1945 , Oppenheimer served as director of the atomic bomb project at Los Alamos, New Mexico. His leadership and organizational skills【5】him the Presidential Medal of Merit in 1946. In 1947 he became director of the Institute for Advanced Studies in Princeton, New Jersey, serving there【6】the year before his death. He was also chairman of the General Advisory Committee of the Atomic Energy Commission from 1947 to 1952 and served【7】as an adviser. In 1954, however, he was suspended from this position【8】his past association with Communists. This action【9】the political atmosphere of the time, as well as the dislike of some politicians and military【10】for Oppenheimer's opposition to development of the hydrogen bomb and his【11】of arms control. His【12】was not really in doubt.【13】, efforts were made to clear his name, and in 1963 the AEC【14】him its highest honor, the Enrico Fermi Award. Oppenheimer【15】his final years to study of the relationship between science and society. He died in Princeton on February 18, 1967.

(1)

A．orientation

B．manipulation

C．development

D．management

常见的点缺陷有（)、间隙原子和置换原子

生物碱分子含有两个氮原子(N1，N2)，请比较该二N原子的碱性强弱，并说明原因。

原子吸收分析主要分为两类，即（)原子吸收分析和（)原子吸收分析。