(function(ul, delay, speed, lineHeight) {
var slideBox = (typeof ul == 'string')?document.getElementById(ul):ul;
var delay = delay||1000;
var speed=speed||20;
var lineHeight = lineHeight||20;
    var tid = null, pause = false;
    var start = function() {
      tid=setInterval(slide, speed);
    }
    var slide = function() {
      if (pause) return;
      slideBox.scrollTop += 2;
      if (slideBox.scrollTop % lineHeight == 0) {
          clearInterval(tid);
          slideBox.appendChild(slideBox.getElementsByTagName('li')[0]);
          slideBox.scrollTop = 0;
          setTimeout(start, delay);
        }
    }
    slideBox.onmouseover=function(){pause=true;}
    slideBox.onmouseout=function(){pause=false;}
    setTimeout(start, 2000);
 })('IssueList', 700, 1);//停留时间，相对速度（越小越快）,每次滚动多少，最好和Li的Line-height一致。