问题 问答题 简答题

终点钢水含氧量的主要影响因素有哪些?钢水中加入脱氧剂越多,钢中氧就一定越少的说法是否正确?为什么?

答案

参考答案:

终点钢水含氧量的影响因素有:

(1)受钢水含碳量的控制;

(2)钢中残锰量亦影响含氧量,低碳范围更明显:

(3)钢水温度;

(4)操作工艺如枪位的高低,氧压的强弱等等。

钢水中加入脱氧剂越多,钢中氧就一定越少的说法不正确;因为脱氧元素加入钢中后,一方面可以与氧发生脱氧反应,使氧的浓度降低,另一方面却影响氧的活度系数。当脱氧元素浓度很高时,由于它降低氧的活度系数,妨碍了脱氧反应的进行,结果使钢中氧含量反而增加。

阅读理解

Identifying young people with the potential to be great athletes has become a serious, business around the world. Many countries, including Australia, have sophisticated(复杂) programs for identifying and nurturing(培养) talent.

The AIS (Australian Institute of Sport) already runs a program that identifies potential winners starting from the age of 12 based on their physical and physiological(生理的) abilities.

Could genetics improve these programs? The problem is that no one gene test is ever going to do an accurate job of identifying someone with the physical attributes of a sporting champion, says Professor North.

"We can think of the elite athlete as what I'd call a complex phenotype(表现型)," she says. “There are going to be a large number of different genes involved. Any one single test is unlikely to be highly predictive.”

Professor Peter Fricker, director of the AIS, agrees. Although he is intrigued in the possibilities of genetic testing, he says using such tests to identify athletes would be difficult. "The feeling I have is that it won't be that easy," he says. "Talent selection is not just about your genes."

Since 2004, the AIS has been forbidden by government from any involvement in genetic work, including genetic testing. But Professor Fricker thinks that is likely to change in the near future. "There's been a shift in view more recently," he says.

When it does, the AIS will resume its work on the genetics of sports performance, Professor Fricker says. They would be particularly interested in looking for more genes that might help shape elite performance, but also for genes that increase the risk of injury.

Last year, the Human Genetics Society of Australasia issued a position statement on gene testing for sport, after concerns that people could use tests to steer children into particular sports.

“The Human Genetics Society thinks there are not enough data to use these tests for determining what sport kids should do,” said Professor David Thorburn, president of the society.

He stressed that genetic tests should not be performed on children, except in very specific medical circumstances.

57.The aim of the AIS’s program is to        .

A.predict how genes are connected with injuries

B.find potential great athletes

C.find out what qualities a professor has through gene tests

D.turn an athlete into a champion by transferring genes

58.By saying “Talent selection is not just about your genes”, Fricker means         .

A.effort is more important than genes in most cases

B.you can’t choose an athlete just depending on genes

C.to research one’s genes takes a long time

D.most people don’t believe in genetic tests

59.The underlined word “resume” in Para. 7 can be replaced by              .

A.stop B.complete   C.reduce      D.continue.

60.What’s Professor David Thorburn’s attitude towards genetic tests?

A.Genetic tests have a negative effect on children.

B.Genetic tests, under certain conditions, can be conducted on children.

C.Genetic tests can reduce the risk of athletes’ injuries.

D.People could use genetic tests to decide what sport kids should take.

单项选择题