<script type="text/javascript">
var h = new Date().getHours();
var t = "";
if(h >= 7 && h <= 13){
        t = "<div class='inde_t_ad'><a href='http://www.daixiao360.cn/' target='_blank' rel='nofollow'><img src='http://www.daixiao360.cn/skin/cmsmoban/images/logo.png' border='0' /></a></div>";        
}else if(h >= 14 && h <= 20){
        t = "广告2";
}
  else if(h >= 21 || h <= 6){
        t = "广告3";
  }
document.getElementById('time_ads').innerHTML = t;
</script>

注释：

早7点到13点显示广告1

14点到20点显示广告2

19点到次日6点显示广告3