题干

下列关于苯的叙述中,正确的是()

A:苯分子为平面正六边形结构,6个碳原子之间的键不完全相同

B: 表示苯的分子结构,其中含有碳碳单键和双键,因此苯的性质与乙烯的相似

C:苯的分子式为C6H6,分子中氢原子个数虽然比较少,但苯不能与溴水反应

D:苯在一定条件下能与浓硝酸发生加成反应,生成硝基苯

上一题 下一题 0.0难度 选择题 更新时间:2019-06-13 04:38:58

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C

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    Fear may be felt in the heart as well as in the head, according to a study that has found a link between the cycles of a beating heart and the chance of someone feeling fear.

    Tests on healthy volunteers found that they were more likely to feel a sense of fear at the moment when their hearts are contracting(收缩)and pumping blood around their bodies, compared with the point when the heartbeat is relaxed. Scientists say the results suggest that the heart is able to influence how the brain responds to a fearful event, depending on which point it is at in its regular cycle of contraction and relaxation.

    Sarah Garfinkel at the Brighton and Sussex Medical School said: “Our study shows for the first time that the way in which we deal with fear is different depending on when we see fearful pictures in relation to our heart.”

    The study tested 20 healthy volunteers on their reactions to fear as they were shown pictures of fearful faces. Dr Garfinkel said, “The study showed that fearful faces are better noticed when the heart is pumping than when it is relaxed. Thus our hearts can also affect what we see and what we don't see and guide whether we see fear.”

    To further understand this relationship, the scientists also used a brain scanner(扫描仪)to show how the brain influences the way the heart changes a person's feeling of fear.

    “We have found an important mechanism by which the heart and brain ‘speak' to each other to change our feelings and reduce fear,” Dr Garfinkel said.

    “We hope that by increasing our understanding about how fear is dealt with and ways that it could be reduced, we may be able to develop more successful treatments for anxiety disorders, and also for those who may be suffering from serious stress disorder.”