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【单选题】
在OSI的7层模型中,主要功能是提供端到端的透明数据运输服务、差错控制和流量撞控制的层次为()。A.
物理层
B.
数据链路层
C.
运输层
D.
网络层
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【简答题】在“氧气、氮气、二氧化硫、二氧化碳、稀有气体”中选择适当的物质填空： （1）用于制造硝酸和化肥的是______； （2）引起温室效应的主要气体______； （3）空气中含量较多且化学性质比较活泼的气体______； （4）可制成五光十色霓虹灯的是______．
【单选题】What will happen if the amino acid sequence is used directly for primer designing?
A.
There would be certainty because the genetic code is unique for each amino acid
B.
There would be uncertainty as the genetic code is degenerate and none of the amino acid is having a unique code
C.
There would be uncertainty as the genetic code is degenerate but some of the amino acids such as methionine are having a unique codon
D.
The amount of uncertainty or certainty is a matter of chance
【多选题】What is the biological and pharmaceutical role of D-amino acids?
A.
Although D-amino acids do not generally occur in proteins, they do serve some special functions in the structure of bacterial cell walls and peptide antibiotics.
B.
Bacterial peptidoglycans contain both D-alanine and D-glutamate. D-Amino acids arise directly from the L isomers by the action of amino acid racemases, which have pyridoxal phosphate as cofactor. Amino acid racemization is uniquely important to bacterial metabolism, and enzymes such as alanine racemase are prime targets for pharmaceutical agents.
C.
One such agent, L-fluoroalanine, is being tested as an antibacterial drug. Another, cycloserine, is used to treat tuberculosis.
D.
Because these inhibitors also affect some PLP-requiring human enzymes, however, they have potentially undesirable side effects.
【简答题】What are amino acids?
【单选题】What has a significant position in the growth of human body tissues?
A.
Essential amino acids.
B.
Non-essential amino acids.
C.
Fat.
D.
Proteins.
【单选题】下列程序段的输出结果是()。 int aa[4][4]={{1,2,3,4},{5,6,7,8},{3,9,10,2},{4,2,9,6}}; inti,s=0; for(i=0;i<4;i++) s+=aa[i][1]; printf("%d\n",s);
A.
11
B.
19
C.
13
D.
20
【简答题】下列程序段的输出结果是()。int aa[4][4]={{1,2,3,4},{5,6,7,8},{3,9,10,2},{4,2,9,6}};int i,s=0;for(i=0;i<4;i++)s+=aa[i][1];printf("%d\n",s);A. 11 B. 19 C. 13 D. 20
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