题干

下列反射活动中,属于简单反射的是( )

A:望梅止渴

B:谈虎色变

C:排尿反射

D:一朝被蛇咬,十年怕井绳

上一题 下一题 0.0难度 选择题 更新时间:2020-01-03 06:44:18

答案(点此获取答案解析)

C

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    America is a mobile society. Friendships between Americans can be close and real, yet disappear soon. They don't feel hurt. If the same two people meet again, even years later, they pick up the friendship. This can be quite difficult for us Chinese to understand .Friendships between us develop more slowly but may become lifelong feelings, extending(延伸)deeply into both families.
T    here is another difficult point for us to understand. Although Americans treat friends warmly in their personal everyday lives, they don't show their politeness to them if it requires a great deal of time. But in China, we are usually generous with our time. We, as hosts, will appear at an airport even in the middle of the night to meet a friend. We may take a day off from our work to act as guides to our friends. It is opposite in America. Americans cannot manage the time to do a great deal with a visitor outside their daily plans. They will probably expect the visitors to get themselves from the airport to the hotels. And they expect the visitors will phone them from there. Once the visitors arrive at their homes, the welcome will be full, warm and real.
    For Americans, it is often considered more friendly to invite a friend to their homes than to restaurants, except for business matters. Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. So accept their hospitality(好客)at home and enjoy your visit in America!

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                                                                     FE复合酶:划时代的高科技成果
      ①酶能够溶解细菌,是20世纪的一个重大发现。而将酶应用于抗菌消毒领域,并证明它比抗生素能更好地担负起对付细菌感染的重任,则是一个划时代的成果。
      ②20世纪三四十年代,在抗生素未被发现之前,细菌感染是威胁人类生命的最重要因素之一。当青霉素、链霉素、磺胺类药物等相继问世后,人类平均寿命提高了几十年。然而随之而来的是一个新的严峻问题:耐药菌出现了。这使得抗生素的剂量越来越大,效果却越来越差。据美国媒体报道,因耐药菌感染,仅延长住院时间和必须使用昂贵的新型抗生素两项,每年就要增加300亿美元的开支。不仅如此,抗生素引起的毒副作用和不良反应也令人吃惊和遗憾。据《健康报》报道,我国每年因药物不良反应死亡的有192万人,住院的有250万人。有人担忧,这样下去我们的后代会不会遭遇一个瘟疫横行却无药可治的悲惨世界。
      ③奇迹就在此时出现;人在葡萄球菌之中发现了溶菌酶。试验证明,它能有效杀灭革兰氏阳性菌,尤其对世界医学界极为棘手的耐药性金黄色葡萄球菌效果显著。随后,世界各地的科学家都展开了对它的研究。1987年,我国复旦大学生命科学院通过基因克隆方法从安全菌中获得了溶葡萄球菌酶(也称FE,意即复旦酶)。之后,复旦酶及FE复合酶制剂被认定为划时代的高科技成果。在原国家教委支持下,由全国174所名牌大学组成的、以开发高科技产品为宗旨的中国高科集团实施了其生产权和销售权的独家转让,并组建了全资子公司——上海高科生物工程有限公司,专门对其进行开发利用。
      ④几年的开发应用实践证明,FE及其复合酶制剂确是非常优良的抗菌剂。它的杀菌机理非常独特,不是简单地在细菌细胞壁上形成一层屏障,而是通过直接裂解菌体细胞壁,彻底杀死细菌,因而不易产生耐药性。作为本质为蛋白质、能随人体新陈代谢而排泄的纯生物制剂,它还具有无任何毒副作用的特点。它使得抗生素带来的耐药性和毒副作用两大难题迎刃而解。以其为原料,上海高科生物工程公司相继开发出用于防止烧伤、外科等手术后期耐药菌感染的FE复合酶消毒剂,可广泛用于手术、器械、餐具、水果等消毒的FE复合酶消毒剂(Ⅱ),用于治疗咽喉炎、口腔溃疡、牙龈炎等的口腔喷雾剂,其中FE复合酶消毒剂成为目前惟一获得卫生部批准的生物型消毒剂。