题干

2000年6月,包括中国在内的六国政府和有关科学家宣布,人类已完成对自身细胞中24条染色体上DNA中的脱氧核苷酸序列的测定,人类基因组草图绘制成功.下列细胞结构中含有被测物质的是(   )

A:高尔基体

B:核糖体

C:细胞质基质

D:细胞核

上一题 下一题 0.0难度 选择题 更新时间:2012-07-05 04:29:09

答案(点此获取答案解析)

D

同类题3

阅读下文,回答问题

阅读的愉悦

李国文

    古人说“开卷有益”,这是绝对的真理。古人还说“敬惜字纸”,在他们眼里,凡有文字的纸张,都应珍惜。据说仓颉造字时,天地鬼神都为之呼喊哭泣,说明文字所具有的强大震撼力量,这种神话当然未必可信,但反映了人们在印刷物不普及时代的文化崇拜和惜物心态。

    应该看到这种书籍信仰,是中国知识分子薪火相传的宝贵精神,是中国文化数千年赖以不坠的物质基础,也是古往今来所有焚书者遭到全体中国人诅咒的根本原因。

    但后来,尤其到了今天,中国有太多的书,而这些太多的书里,有着太多的糟粕,也是令想读书的人颇感挠头的烦恼。如果无所适从、茫然失措、因噎废食,糟粕固然没了,精华也随之而去。其实,不去其糟粕,何来精华?读书的全部愉悦,就在这种抉择之中。好和坏,自己判断,糟粕和精华,自己说了算,予取予弃的生杀大权,自己把握。这种不受别人干涉,不看别人脸色,不以别人的意志为意志,不以别人的标准为标准,在阅读中所得到的自由,便是无与伦比的快乐了。

    我的阅读主张,说来简单,与胃口的好恶决定多吃、少吃,或者不吃,是差不多的。那些有学问对我有用处的书,我用吃橄榄的办法阅读,反复咀嚼,徐徐品味;那些有学问然而对我用处不大的书,我用吃甘蔗的办法阅读,啜其甜汁,吐其渣滓;那些没有什么学问也没有什么用处的书,也许在某些正经人和革命者看来,不属大雅的书,视若敝屣的书,我就用吃石榴的办法来阅读了。固然,石榴这东西,能食的部分极其少,不能食的部分尤其多,但此物之苦之涩之酸外的,偶然一得之甘旨,忽然意外的清香,也是一种难能可贵的口味。

    有时,阅读闲书的愉悦,所带来的身心充实,胜过很多灌输的学问。所以,碰上这类闲书,我总是要拿起来翻一翻的。不惮吹灰之力,也许获益其中,哪怕分文不值,弃之也不嫌迟。当然,阅读,有快乐,也有不快乐。有读得兴起,拍案叫绝的愉悦;也有读得没劲,大倒胃口的不愉悦。有广告做得极红火,评论捧得极热烈,拿在手中,看在眼里,不过金玉其外,败絮其中的不愉悦;也有不见报章介绍,也无名家推荐,随意买来,便中翻阅,倒能提高修养,裨益身心的愉悦。因此,阅读各式各样的书籍越多,识别好坏良莠的能力越高,从精神食粮中摄取的营养就更丰富,获得的愉悦也更广泛。

    鲁迅说:“一说起读书,就觉得是高尚的事情,其实这样的读书,和木匠磨斧头,裁缝的理针线并没有什么分别,并不见得高尚,有时还很苦痛,很可怜。”由此可见,求知求生,是同样的道理。春华秋实,你付出的多,你收获的也多,只要读书,就有收获。书籍,是人类智慧的结晶,多读一本书,便多一分智慧的光亮。

同类题5

完形填空

    Elephants are big,but Teensy was the smallest of them.Teensy tried everything she could think of to help herself grow.She put her legs out straight.She ate a lot.However,nothing seemed to 1.

    One day Teensy went with the elephants to have lunch.They stopped in front of some trees and found their favourite green leaves.Teensy raised her nose and tried again and again.but  she couldn't 2the branches.Not even the low ones!

    At the end of the day,Teensy was with the rest of the elephants watching the 3.But Teensy couldn't see very much."Excuse me,"said Teensy politely,"I'd like to see more than your knees,if you please."But the elephants didn't hear little Teensy.They were too 4 enjoying the sunset.Teensy sat down and waited 5for them to finish admiring the sunset.She knew she was too little to walk away by herself,so she sat and6 what the sunset must look like."Oh,I guess it is too pretty for words!"she sighed.Teensy was very sad."Oh,woe is me."she said.Suddenly,Teensy heard a tiny voice."What is woe?"the voice said.Teensy looked down and saw a mouse."Woe means 7"said Teensy.She told the mouse about seeing only elephant 8 instead of the sunset.

    "I'm too little,"she said.

    "Why?You're not little at all,"said the mouse.

    "Do you think so?"replied Teensy,"I'm sorry you're so small.I know how it feels.""Don't be sorry,"said the mouse."I like being small!I can always fit into corners.

    "Wow,"said Teensy,"so being9CAN be good."

    "You're right.Little or big,you should always be10 of who you are."said the mouse.