说明：  利用系统提供的接口-互斥体实现只运行一个应用程序实例，防止同时运行多个程序产生冲突，例如杀毒软件这样的程序。程序是用API函数实现，但是稍加修改或不修改就可使用，挺方便。
(Use of system interface- mutex to achieve only run an application example of running multiple programs at the same time to prevent conflicts, such as antivirus software such procedures. Procedure is used API function, but slightly modified or not modified to use, very convenient.)