UpdatePanel in Master Page.

//需要加入以下代码

     protected   void  Page_Init( object  sender, EventArgs e)
    {
        AsyncPostBackTrigger trigger  =   new  AsyncPostBackTrigger();
        trigger.EventName  =   " Tick " ;
        trigger.ControlID  =   this .Timer1.UniqueID;
         this .update1.Triggers.Add(trigger);
    }