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问题 单项选择题

同种异型抗原决定簇存在

A．HLA分子抗原肽结合区
B．HLA分子Ig样区
C．HLA分子跨膜区
D．HLA分子胞内区
E．HLA分子γ链

答案

参考答案：A

解析： 本题要点为HLA的分子结构及各部分作用，抗原肽结合区为多肽性部位，Ig样区与CD4和CD8分子结合，跨膜区将HLA分子锚定在细胞膜上，胞内区参与胞内信号传递。

单项选择题

(1) is used to ensure the confidentiality,integrity and authenticity of the two end points in the private network． (2) ，an application—layer protocol，authenticates each peer in an IPSec transaction．IKE negotiates security policy，determining which algorithm may be used to set up the tunnel．it alsohandles the exchange of session keys used for that one transaction．

Networks that use (3) to secure data traffic can automatically authenticate devices by using (4) ，which verify the identities of the two users who are sending information back and forth．IPSeccan be ideal way to secure data in large networks that require secure connections among many devices．

Users deploying IPSec can (5) their network infrastructure without affecting the applications on individual computer．The protocol suite is available as a software-only upgrade to the networkinfrastructure．This alows security to be implemented without costly changes to each computer．Mostimportant，IPSec allows interoperability among different network devices，PCs and other computingsystems．

5（）

A．secure

B．relation

C．script

D．strict
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单项选择题

在Internet中用于远程登录服务的是（）。

A.FTP

B.E-mail

C.Telnet

D.WWW
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