问题 多项选择题

影响巴比妥类药物镇静催眠作用强弱和快慢的因素有()

A.pKa

B.脂溶性

C.5-取代基

D.5-取代基碳数目超过10个

E.直链酰脲

答案

参考答案:A, B, C

解析:巴比妥类药物为作用于中枢神经的镇静催眠药。药物作用于中枢需有较大的脂溶性才易于透过血脑屏障达到中枢神经系统。5-位上两个取代基应为亲脂性基团,其碳原子总数在4~8之间,使药物具有适当的脂溶性。此外巴比妥类药物必须有适宜的解离度才易于透过生物膜,穿过血脑屏障,因此5-位上必须有两个取代基。因为5-位上若只有一个取代基(剩余一个未被取代的氢)或5-位上没有取代基时,酸性强,pKa值低,在生理条件(pH=7.4)下易解离而不易透过生物膜,中枢镇静作用很弱或没有作用。巴比妥类为环状双酰脲类,若开环为直链酰脲则镇静催眠作用弱,在临床上已不再使用。

阅读理解

I live in the land of Disney, Hollywood and year - round sun.You may think People ,n such an attractive, fun - filled place are happier than others.If so you have some mistaken ideas about the nature of happiness.

Many intelligent people still think fun equals happiness.The truth is that fun and happiness have little or nothing in common.Fun is what we experience during an act.Happiness is what we experience after an act.It is a deep, long-lasting emotion.

Going to an amusement park or a ball game, watching a movie or television are fun activities that help us relax, temporally forget our problems and maybe even laugh.But they do not bring happiness, because their positive effects end when the fun ends.

I have often thought that if Hollywood stars have a role to play, it is to teach us that happiness has nothing to do with fun.They have constant access to exciting parties, fancy cars, expensive homes, everything that spells "happiness" But in memoir(回忆录) after memoir, they expose Ac unhappiness hidden beneath all their fun: depression, alcoholism, drug addiction, broken marriages and loneliness.

Ask a bachelor why he resists marriage even though he finds dating to be less and less satisfying.If he is honest, he will tell you that he is afraid of making a commitment.For commitment is in fact quite painful.The single life is filled with fun, adventure and excitement.Marriage has such moments, but they are not its most distinguishing features.

Similarly, couples that choose not to have children are deciding in favor of painless fun over painful happiness.They can dine out whenever they want and sleep as late as they want.Couples with babies are lucky to get a whole night' s sleep.I don't know any parent who would choose the word fun to describe raising children.

Understanding and accepting that true happiness has nothing to do with fun is one of the most liberating realizations we can ever come to.It liberates time: now we can devote more hours to activities that can truly increase our happiness.It liberates money: buying that new car or those fancy clothes that will do nothing to increase our happiness now seems pointless.And it frees us from envy: we now understand that all those rich and famous people we were so sure are happy because they are always having so much fun actually may not be happy at all.

小题1:What is the passage mainly about?

A.Fun and happiness.

B.Success and satisfaction.

C.Marriage and commitment.

D.Entertainment and responsibility.小题2:The author probably agrees that ____.

A.fun creates long - lasting satisfaction

B.long - standing fun may lead to happiness

C.fun is short-lived while happiness is long-lasting

D.fun provides enjoyment while pain leads to happiness小题3:What does the author think of marriage?

A.It ends in pain.

B.It means commitment.

C.It affords greater fun.

D.It leads to raising children.

【小题14If one gets the real meaning of happiness, he ____.

A.will start a business

B.won' t place too much value on money

C.will seek for freedom

D.won't devote himself to his family

单项选择题 A1/A2型题