//suspendcode="<DIV id=backi style='right:0px;POSITION:absolute;TOP:200px;'><a href='javascript:history.back()' title='后退'><img border=0 src=\"images/lw.gif\" ></a><br><a href='#top' title='顶部'><img border=0 src=\"images/uw.gif\" ></a><br><a href='#bottom' title='底部'><img border=0 src=\"images/dw.gif\" ><br><a href='javascript:history.forward()' title='前进'><img border=0 src=\"images/rw.gif\" ></a></a></div>" 
suspendcode="<DIV id=backi style='right:0px;POSITION:absolute;TOP:200px;'><a href='#top' title='顶部'><img border=0 src=\"images/uw.gif\" ></a><br><a href='#bottom' title='底部'><img border=0 src=\"images/dw.gif\" ></a></div>" 

document.write(suspendcode); 
lastScrollY=0; 
function heartBeat(){ 
diffY=document.body.scrollTop; 
percent=.1*(diffY-lastScrollY); 
if(percent>0)percent=Math.ceil(percent); 
else percent=Math.floor(percent); 
document.all.backi.style.pixelTop+=percent; 
lastScrollY=lastScrollY+percent; 
} 
window.setInterval("heartBeat()",1);