lastScrollY=0;
function heartBeat(){ 
var diffY;
if (document.documentElement && document.documentElement.scrollTop)
   diffY = document.documentElement.scrollTop;
else if (document.body)
   diffY = document.body.scrollTop;
else
{/*Netscape stuff*/}
  
//alert(diffY);
percent=.1*(diffY-lastScrollY); 
if(percent>0)percent=Math.ceil(percent); 
else percent=Math.floor(percent); 
document.getElementById("web_ad").style.top=parseInt(document.getElementById("web_ad").style.top)+percent+"px";
lastScrollY=lastScrollY+percent; 
//alert(lastScrollY);
}
suspendcode="<DIV id=\"web_ad\" style='right:5px;POSITION:absolute;TOP:330px; border:0px solid #fff;'><a href='#100'><img style='border:0px;' src='/aovt/template/images/top.gif' alt='返回顶部' /></a></div>";
document.write(suspendcode); 

window.setInterval("heartBeat()",1);