题干

某蛋白质分子由N条肽链组成,已知它共由M个氨基酸组成,则此蛋白质中至少含有的氧原子数与氮原子数共有(   )

A:(M+N)个

B:(2M-N)个

C:(2N+M)个

D:(2M+N)个

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答案(点此获取答案解析)

D

同类题1

阅读下面文章,完成下列各题。

渴望倾听

马亚伟

      ①看过一篇小说,大概意思是说:有一个人和别人打赌把自己关在一间屋子里,如果他能在十年间不和外界有任何接触,就可以赢得一笔巨款。于是,他开始了一个人的幽居生活。熬过了漫长的十年,最后,他终于坚持到约定的期限。但是,他却放弃了巨款,悄然离开。只留下一封信。信中说,十年来,他饱尝了孤独的痛苦,寂寞的摧残。他悟出了一个道理:人拥有比金钱更为重要的东西,那就是感情交流。于是,他重新融入人群,开始新的生活。

      ②可以想象,一个人的幽居一定会如同在沙漠中独行,满目荒凉和绝望,内心巨大的空洞会把人吞噬掉。人生存的精神支柱,人最殷切的愿望,应该是在与别人的交流中获取丰富的生活体验,从中收获情感的源泉。

      ③与人交流,人生码头才百舸千帆,丰富多彩。

      ④也听说过不同领域的一些艺术大师离群索居,进行艺术创作。可是,再孤独的创作,也需要与欣赏者沟通。梵高、卡夫卡,这些人有着超越时代的艺术才华,他们的作品都是在他们去世后才引起了轰动。其实,只是上帝开了一个玩笑,让他们提前很多年来到这个世界,让他们以一种特立独行的姿态寂寞地面对世人。不过,他们孤独地创作不息,正是因为他们要宣泄,要表达,要沟通,要交流。因为他们知道,一定会有一颗虔诚的灵魂聆听他们的独吟、呐喊、甚至咆哮。总会有人听懂他们,即使是很多年以后。

      ⑤古人遁隐田园山林,与嘈杂的红尘隔绝,与污浊的官场隔绝,可并不是和人隔绝。陶渊明隐居后,还会和农民一起其乐融融地劳作,“日入相与归,壶浆劳芳邻”。孟浩然喜欢田园生活,闲暇时,他会和农人一起“把酒话桑麻”。王维一个人独往于山林中,偶然遇到个林中的老翁,还会“谈笑无还期”。

      ⑥沟通交流是每个人的愿望。即便鲁滨逊漂流到孤岛上,尚且需要一个“星期五”来作伴。

      ⑦我们平凡百姓,更加需要与人沟通交流。一颗孤独的灵魂不能走得很久很远。漫长的人生旅途中,一个人的行走,没有人扶持关照,我们的脚步会沉重如铅,一个人的空间,也必定狭小如囚笼。

      ⑧正是因为人类沟通交流的愿望如此强烈,通讯技术才得以飞速发展。时至今日,我们已经有了很多极为便捷的交流方式和途径。人与人之间的距离越来越小。

      ⑨每一颗心都渴望倾听。让我们搭建一个心灵的城堡,倾听每一颗心的跳动,为自己,为他人。

同类题5

阅读理解

    Technology offers conveniences such as opening the garage door from your car or changing the television station without touching the TV.

    Now one American company is offering its employees a new convenience: a microchip implanted in their hands. Employees who have these chips can do all kinds of things just by waving their hands. Three Square Market is offering to implant microchips in all of their employees for free. Each chip costs $300 and Three Square Market will pay for the chip. Employees can volunteer to have the chips implanted in their hands. About 50 out of 80 employees have chosen to do so. The president of the company, his wife and their children are also getting chips implanted in their hands.

    The chip is about the size of a grain of rice. Implanting the chip only takes about a second and is said to hurt only very briefly. The chips go under the skin between the thumb and forefinger. With a chip in the hand, a person can enter the office building, buy food, sign into computers and more, simply by waving that hand near a scanner. The chips will be also used to identify employees. Employees who want convenience, but do not want to have a microchip implanted under their skin, can wear a wristband or a ring with a chip instead. They can perform the same tasks with a wave of their hands as if they had an implanted chip.

    Three Square Market is the first company in the United States to offer to implant chips in its employees. Epicenter, a company in Sweden, has been implanting chips in its employees for a while.

    Three Square Market says the chip cannot track the employees. The company says scanners can read the chips only when they are within a few inches of them. “The chips protect against identity theft, similar to credit cards.” The U.S. Food and Drug Administration approved the chips back in 2004, so they should be safe for humans, according to the company.

    In the future, people with the chips may be able to do more with them, even outside the office. Todd Westby is Chief Executive Officer of Three Square Market. He says, “Eventually, this technology will become standardized allowing you to use this as your passport, public transit, all purchasing opportunities, etc.”