题干

科学家袁隆平利用我国野生水稻基因,培育出了高产杂交稻,国家推广种植后,大幅度增加了我国粮食产量。野生水稻基因的成功利用,充分反映了(  )

A:要保护各种生态系统的平衡

B:保护地球上生物的多样性,是人类储备资源的一种方式

C:各种自然资源之间,是相互联系、相互影响、相互制约的

D:地球养活人类的能力是无限的

上一题 下一题 0.0难度 选择题 更新时间:2019-08-24 11:35:09

答案(点此获取答案解析)

B

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       Some thing in chocolate could be used to stop coughs and lead to more effective medicines,say UK researchers.

Theirstudy found that theobromine, found in cocoa, was nearly a third more effectivein stopping coughs than codeine, which was considered the best cough medicineat present.

    The   Imperial College London researchers who published their results online said thediscovery could lead to more effective cough treatment. “While coughing is notnecessarily harmful, it can have a major effect on the quality of life, andthis discovery could be a huge step forward in treating this problem,” said Professor Peter Barnes.

Tenhealthy volunteers were given theobromine, codeine or placebo, a pill thatcontains no medicine, during the experiment. Neither the volunteers nor theresearchers knew who received which pill. The researchers then measured levelsof capsaicin(辣椒素),which is used in research to cause coughing and as a sign of how well themedicines are stopping coughs.

Theteam found that, when the volunteers were given theobromine, the capsaicin needto produce a cough was around a third higher than in the placebo group. Whenthey were given codeine they need only slightly higher levers of capsaicin tocause a cough compared with the placebo.

   There searchers said that theobromine worked by keeping down a verve activity(神经活动), which caused coughing. They alsofound that unlike some standard cough treatments, theobromine caused no sideeffects such as sleepiness.