搜题请搜索小程序“爱下问搜题”
问题 单项选择题 B型题

用于定量的参数是（）

A.色谱峰高或峰面积

B.死时间

C.色谱峰保留时间

D.色谱峰宽

E.色谱基线

答案

参考答案：A

解析：本题考查色谱基本理论。色谱峰高或峰面积可用于定量；死时间：不保留组分（不溶于固定相或不被固定相所吸附）的保留时间；保留时间：由进样到某组分色谱峰峰顶的时间间隔；色谱蜂宽：通过色谱峰两侧的拐点作切线，在基线上的截距，用于衡量柱效；基线：在操作条件下，没有组分流出时的流出曲线，基线反映仪器噪音随时间的变化。

单项选择题

唯一能区别一个控件的属性是 ______。

A．Index

B．Text

C．Name

D．Caption
查看答案
单项选择题

Typically, these are concern with the establishment of (66) the network and with the control of the flow of messages across this channel. The provision of such facilities is only part of the network requirements, however, since in many applications the communicating computers may be of different types. This means that they may use different programming languages and, more importantly, different forms of (67) interface between user(application)program, normally referred to, as application processes or APs, and the underlying communication services may be (68) For example, one computer may be a small single -user computer, while another may be a large (69) system. In the earlier days of computer communication, these issues meantthat only closed communities of computers ( that is, from the same manufacturer) could communicate with each other in a meaningful way. IBM’s Systems Network.
Architecture (SNA) and DEC’s Digital Network Architecture (DNA) are just two examples of Communication software packages produced by manufacturers to allow their systems to be int erconnected together. These proprietary packages, however, of which there am still many inexistence, do not address the problem of universal interconnect ability, or open systems interconnection. In an attempt to alleviate this problem, (70) , in the late 1970s, formulated a reference model to provide a common basis ( or the coordination of standards developments and to allow existing and evolving standards activities to beplaced into perspective with one another.

A．database

B．data representation

C．protocols

D．data communication
查看答案