题干

下列关于干细胞的叙述中,正确的是(   )

A:胚胎干细胞在形态上表现为体积大,细胞核小,核仁明显

B:肝脏干细胞分化形成肝脏细胞的过程表现了细胞的全能性

C:异体造血干细胞移植成功后,不影响患者的血型

D:干细胞分化形成不同组织细胞是基因选择性表达的结果

上一题 下一题 0.0难度 选择题 更新时间:2019-11-25 09:58:49

答案(点此获取答案解析)

D

同类题2

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    One fine afternoon I was walking along Fifth Avenue when I remembered that it was necessary to buy a pair of socks. I turned into the first sock shop that caught my eye, and a boy clerk who could not have been more than 17 years old came forward.

    “What can I do for you, sir?”

    “I wish to buy a pair of socks.”

    His eyes glowed. “Did you know that you had come into the best place in the world to buy socks?” I had not been aware of that.

    “Come with me,” said the boy happily. He began to haul (用力拖) down from the shelves box after box.

    “Hold on, boy, I am going to buy only one pair!”

    “I know that,” said he, “but I want you to see how beautiful these are. Aren't they wonderful?” There was on his face an expression of joy, as if he were showing to me the mysteries of his religion.

    “My friend,” said I, “if this is not just the enthusiasm (热情) that comes from novelty (新鲜), if you can keep up this day after day, in ten years you will own every sock in the United States.”

    In many shops the customer has to wait for someone to serve him. And when finally some clerk does notice you, you are made to feel as if you were disturbing him. He displays no interest either in you or in the goods he is paid to sell.

    Yet possibly that very clerk who is now so cold began his career with enthusiasm. As time goes by, the enthusiasm is gradually gone; his only pleasures were found outside of working hours. He became a mechanical (机械的), not inspired, salesman.

    I have observed such change in the lives of so many people in so many occupations that I have come to the conclusion that the fastest road to failure is to do things mechanically.