题干

下列有关科学发现的说法正确的是(    )

A:沃森和克里克成功构建DNA双螺旋结构模型,并进一步提出了DNA半保留复制的假说

B:施莱登和施旺建立了细胞学说,并提出了一切生物都是由细胞发育而来的观点

C:罗伯特森提出生物膜的模型:所有的生物膜都由脂质﹣蛋白质﹣脂质三层结构构成

D:斯他林和贝利斯首次发现了动物激素﹣﹣促胰液素,由胰腺分泌

上一题 下一题 0.0难度 选择题 更新时间:2019-09-16 09:15:47

答案(点此获取答案解析)

A

同类题2

Bobby was sitting out in his back yard in the snow. There were a few holes in his shoes. He thought hard, but he could not come up with an idea for his mother's Christmas gift.
Ever since his father had died three years ago, his mother worked nights at the hospital, but the small money she made could hardly be enough for their needs.
Although the family lacked in money and material things, they got more love in the family. The children ran the family when their mother was absent. All three of Bobby's sisters had already made beautiful gifts for their mother.
It was Christmas Eve already, and he had nothing. Bobby started to walk down to the street. He walked from shop to shop. Everything seemed so beautiful and so far away. It was getting dark. Suddenly he found a shiny dime (一角硬币) on the ground. Never has anyone felt so wealthy as Bobby did at the moment. It was enough to buy a rose with one dime.
He went inside a flower shop. When the owner asked if he could help him, Bobby took out the dime and asked if he could buy one flower. The shop owner looked at Bobby, then said, "You just wait here and I’ll see what I can do for you."
The shop owner returned holding a dozen of red roses in his hand. Bobby's heart sank (下沉) as the owner put them gently into a long white box. "That will be a dime, young man," said the shop owner, reaching out his hand for the dime. Slowly, Bobby moved his hand to give the man his dime.
Then the shopkeeper's wife appeared. "Where are the red roses?"
The shop owner said, "A strange thing happened to me this morning. I thought I heard a voice telling me to leave a dozen of my best roses for a special gift. When I saw that little boy tonight, I knew who that voice was."