var time = 500;
    var h = 0;
    function addCount()
    {
        if(time>0)
        {
            time--;
            h = h+5;
        }
        else
        {
            return;
        }
        if(h>300)  //高度
        {
            return;
        }
        document.getElementById("ads").style.display = "";
        document.getElementById("ads").style.height = h+"px";
        setTimeout("addCount()",30); 
    }
    
    window.onload = function showAds()
    {
        addCount();
        setTimeout("noneAds()",12000); //停留时间自己适当调整
    }

    var T = 1000;
    var N = 266; //高度
    function noneAds()
    {
        if(T>0)
        {
            T--;
            N = N-5;
        }
        else
        {
            return;
        }
        if(N<0)
        {
            document.getElementById("ads").style.display = "none";
            return;
        }
        
        document.getElementById("ads").style.height = N+"px";
        setTimeout("noneAds()",30); 
    }
document.write('<div id=\"ads\" style=\"margin:auto; display:none; top:0px; height:0px; background-color:#c00301; overflow:hidden; text-align:center;\"><img src=\"http://www.90576.com/2012adv/mpic/c00301.jpg\"    width=\"1003\" height=\"300\" border=\"0\"></div>');