var intervalId = null; 
	function slideAd(id,nStayTime,sState,nMaxHth,nMinHth){ 
	this.stayTime=nStayTime*1000 || 3000; 
	//设置滚动高度
	this.maxHeigth=nMaxHth || 600; 
	this.minHeigth=nMinHth || 2.5; 
	this.state=sState || "down" ; 
	var obj = document.getElementById(id); 
	if(intervalId != null)window.clearInterval(intervalId); 
	function openBox(){ 
	var h = obj.offsetHeight; 
	obj.style.height = ((this.state == "down") ? (h + 2) : (h - 2))+"px"; 
	if(obj.offsetHeight>this.maxHeigth){ 
	window.clearInterval(intervalId); 
	intervalId=window.setInterval(closeBox,this.stayTime); 
	} 
	if (obj.offsetHeight<this.minHeigth){ 
	window.clearInterval(intervalId); 
	obj.style.display="none"; 
	} 
	} 
	function closeBox(){ 
	slideAd(id,this.stayTime,"up",nMaxHth,nMinHth); 
	} 
	//设置滑动速度
	intervalId = window.setInterval(openBox,20); 
	}