题目:
维系DNA二级结构的作用力不包括()。
A.氢键
B.碱基堆积力
C.肽键
D.盐键
答案:
参考答案:C
维系DNA二级结构的作用力不包括()。
A.氢键
B.碱基堆积力
C.肽键
D.盐键
参考答案:C
下列说法正确的是( ) A.原子是由位于中心的原子核和核外电子组成的 B.原子、分子、电子按空间尺度由小到大排序是:原子→分子→电子 C.“纳米”是一个十分庞大的长度单位 D.超导体的导电性能介于导体和绝缘体之间 |
列式计算. (1)一个数的
(2)
|
阅读下面短文,掌握其大意,然后从36—55各题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题卡上涂黑。 My own "truest" Christmas stands out from all the others, which is the one when the meaning of the day shone clearest.Recently divorced, I had no 36 and was on my way to the employment office.It was pouring, but I had no umbrella, for my old one had 37 apart, and I could not afford another one. I got in a streetcar and there 38 the seat was an umbrella leaning with a silver handle 39with jewels.I had never seen anything so lovely.I 40 the handle and saw a name carved there.The 41_procedure would have been to 42 the umbrella to the conductor, while I 43 to take it with me and find the owner myself. Then I 44 a telephone book for the name on the umbrella and got it.A lady answered my call and she was so 45 that I forgot I was looking for a job and went directly to her small house.There, she wanted to give me a(an) 46 , but her excitement at getting back this special possession was 47 that to have accepted money would have 48 something. The next six months were 49 .I was able to get only temporary 50 here and there for a small salary. 51 , when reaching home, 1 made myself smile, pretending to be happy to meet my daughter Peggy.There, she opened the door for me and 52 herself in my arms, screaming and demanding that we decorate the tree immediately.But when I looked at the cold pans and cans in he cold little kitchen, misery 53 me. Suddenly the doorbell rang, there stood a delivery man."This is a 54 ," I said, but he read the name on the parcels and they were for me.I looked for the name of the sender and found it was the lady. Our dinner the night was the most delicious in my life.Then I put Peggy to bed and 55 her gifts up around the tree and a sweet peace flooded me like a blessing.
|
下列为慢性阻塞性肺疾病(COPD)的是
A.慢性支气管炎
B.肺气肿
C.肺心病
D.肺功能检查出现气流受限、并不能完全可逆
E.哮喘
正常脉象的特征是()()