题干

下列说法不正确的是

A:大米富含淀粉

B:加碘食盐含有碘酸钾(KIO3)

C:人体必需的微量元素就是维生素

D:人体必需的微量元素不都是金属元素

上一题 下一题 0.0难度 选择题 更新时间:2017-08-03 07:19:53

答案(点此获取答案解析)

C

同类题1

阅读下文,完成小题。

    生物钟是一门跨学科科学。生物钟学的中心概念是生物节律。

    生物节律是一种十分奇特的机制。它可以帮助生物体适应不断变化的情况。每个器官和系统都有自己的节律,而它们之间又是互相衔接的。譬如,心跳平均每分钟70次。而晚上只有60至50次。处于运动状态时,心跳则会加快。呼吸和新陈代谢也如此。为了适应不断变化的环境,自然界就产生了生物节律。

    生物节律是自然界产生的生物现象。它存在于生命的各个阶段。研究表明,生物节律对肌体适应不良生态因素起着重要作用,同时影响到疾病的治疗和预防。生物钟医学中还有一个概念——非同步。它犹如钟表中的尺寸不同的齿轮。当齿轮相吻合时,就会不停地运动。当齿轮出现故障时,肌体就有了毛病。

    坐飞机到外地就是一个例子。人已经习惯于晚上呆在某个地方,如果换了地方,肌体就需适应变化。如果不适应,人就会懒洋洋、工作效率低下、头疼、精神紧张、自我感觉不佳等。这一切都可称作非同步。

    一昼夜中,人体的机能是不断变化的,病亦如此,而且是严格遵循规律的。就拿高血压来说,早晨血压会升高,白天会下降并趋于正常,夜间又会升高。借助血压计可以测量出血压在一天中的变化情况。人可以根据血压升降的规律服药,而不是死板地一日三次。也就是说,一天服一次药就可以达到稳定血压的目的。少服药可以减少药物对人体的副作用,又可省钱。

    同样,针灸和理疗也要选择最佳时刻。选择的时间不当,也许还会造成不良后果。科学家曾经做过实验。他们给家鼠注射了增加肌肉收缩力的药物。药量相同,注射时间不同,结果大相径庭。早上注射,家鼠几乎全军覆没,而晚上注射则无一死亡。

    现代生物钟医学的主要研究课题是,研究纠正人体生物节律的方法和药剂。根据“生物钟”选择最佳时刻治疗疾病,能够收到比平时更好的效果。从上个世纪60年代末起使用的方法是借助理疗仪。用得相当多的还有调节褪黑素生成的药物。

    要学会维持正确的生物钟,否则就会出现生理和心理紧张。要努力使自己的社会活动节律与自己的生物钟相吻合,这样才能精力充沛和高效率地工作。

同类题4

阅读理解

    If you want to become a better reader, what should you know about speed of reading?

    Some people read very rapidly(快速地),while others read very slowly. But which one is better?

    The rapid reader may be a good reader when he reads a storybook for fun. But he may not be able to slow down enough to read directions carefully. He may read so rapidly that he does not take time to understand fully the ideas and information which are important to remember.

    The slow reader may be a good reader when he reads directions for making something. But he may spend too much time in reading a simple story which is meant to be enjoyed but is not important enough to be remembered.

    So, you see, either a rapid reader or a slow reader is not really a good one. If you wish to become a better reader, here are four important things to remember about speed of reading.

    1  Knowing why you are reading will often help you to know whether to read rapidly or slowly.

    2  Some things should be read slowly throughout. Examples are directions for making or doing something, science and history books, and Maths problems. You must read such things slowly or remember each important step and understand each important idea.

    3  Some things should be read rapidly throughout. Examples are simple stories for enjoyment, letters from friends and bits of news from hometown papers.

    4  In some of your reading, you must change your speed from fast to slow and slow to fast, as you go along. You will need to read certain pages rapidly and then slow down and do more careful reading when you come to important ideas.