var time = 500;
    var h = 0;
	var H=0;
    var N = 0; //高度
	
    function addCount()
    {
        if(time>0)
        {
            time--;
            h = h+5;
        }
        else
        {
            return;
        }
        if(h>H)  //高度
        {
            return;
        }
        document.getElementById("downads").style.display = "";
        document.getElementById("downads").style.height = h+"px";
        setTimeout("addCount()",30); 
    }
    
    function showDownAds(height,content)
    {
	    document.write('<DIV id="downads" style="display:none; width:1001px; top:0px; height:0px;margin:0 auto; overflow:hidden">'+content+'</DIV>');
		H=height;
		N=height;
        addCount();
        setTimeout("noneAds()",15000); //停留时间自己适当调整
    }

    function noneAds()
    {
        N = N-5;
		if(N<0)
        {
            document.getElementById("downads").style.display = "none";
            return;
        }
        
        document.getElementById("downads").style.height = N+"px";
        setTimeout("noneAds()",30); 
    }