门电路是用以实现逻辑关系的电 子电路，与我们所讲过的基本逻辑关 系相对应，门电路主要有：与门、或 门、与非门、或非门、异或门等。 在数字电路中，一般用高电平代 表1、低点平代表0，即所谓的正逻辑 系统

5.1 触发器的电路结构与工作原理 5.2 触发器逻辑功能的转换 5.3 触发器的工作特性与参数

6.1 时序逻辑电路的基本概念 6.2 时序逻辑电路的分析方法 6.3 同步时序逻辑电路的设计方法

所谓编码就是赋予选定的一系列二进制代码以 固定的含义。（从码的角度看） 给输入信号一个特定代码。（从信号角度看） n个二进制代码（n位二进制数）有2n种不 同的组合，可以表示2n个信号

In the deliberations of scholars, policy analysts, and policy makers, power and influence. Yet the historical record shows that television has not changed the economics of attention not merely a fluke or just ironic. It points to a major impediment to the development of information societies. State-owned-and-controlled media can be an important policy lever for overcoming this opposition

In this paper we discuss the role of the media in pressuring corporate managers and directors to behave in ways that are \socially acceptable. Sometimes this coincides with shareholders' value maximization others not. We provide both anecdotal and systematic evidence that media affect companies' policy toward the environment and the amount of corporate resources that are diverted to the sole advantage of controlling shareholders. Our results have important consequences for the focus of the corporate governance debate and for the feasibility of reforms aimed at improving corporate governance around the

Persons freedom to communicate, and their ability to do so effectively, has long been recognized as a crucial component of a society that respects human dignity and provides the conditions for humans to flourish. Government actions that suppress persons'speech and other forms of communication have been rightly subject to scrutiny and challenge Governments have also recognized the importance of affirmative steps to enhance persons opportunities for communications, such steps include improving education and supporting public forums. Communication is not only a personal and political good

1线性电子线路与非线性电子线路 2非线性电子线路在通信系统中的应用

8-1 集成稳压电路 8-2 开关稳压电源

6-1数字调幅(ASK) 6-2数字调频(fsK 6-3、数字调相