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问题 单项选择题

吗啡戒断症状产生主要是由于

A．去甲肾上腺素能神经元活性增强

B．胆碱能神经元活性增强

C．多巴胺能神经元活性增强

D．5-羟色胺能神经元活性增强

E．脑啡肽能神经元活性增强

答案

参考答案：A

解析：

吗啡类药物除镇痛外，可引起欣快，易于成瘾。吗啡类戒断症状的产生主要与吗啡受体废用性增敏现象有关，吗啡受体长期被阻断后出现废用性增敏，致使在停药期间受体敏感性过高，去甲肾上腺素能神经元活性增强，而出现戒断症状。故选A。

考点：吗啡戒断症状

单项选择题

下列哪一项描述不正确

A．成年女性一般以胸式呼吸为主

B．腹式呼吸多见于儿童及成年男性

C．腹水及巨大卵巢囊肿患者一般为腹式呼吸

D．肝脾大及胃肠胀气患者一般为胸式呼吸

E．腹式呼吸可分为顺呼吸和逆呼吸两种
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单项选择题

Visitors to this country are normally admitted for six months, but foreign students can usually stay for one year. They must (52) an educational institution, and they are required to study for a (53) of fifteen hours a week on a daytime course. Prospective students have to show that they can afford their studies, and that they have sufficient (54) resources to support themselves (55) in this country.

In order to work here the foreigner needs a work permit, (56) must be applied for by his prospective employer. The problem here is that the Department of Employment has the right to grant or (57) these permits, and there is little that can be done (58) it; it would be extremely unwise for a foreign visitor to work (59) a permit, since anyone doing so is liable to immediate deportation (驱逐出境). There are some people from the European countries, who are often given (60) residence permits of up to five years. Some other people, such as doctors, foreign journalists, authors and others can work without permits, and foreign students are normally allowed to (61) part-time jobs while they are studying here.

57().

A.receive 

B.refuse 

C.oppose 

D.accept
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