function pic_adv(colnum) {
 var v1=Math.random();
 var dhref="<a href=http://ad.focus.com.cn/advmgr/advcolumns/advurl.php?colid=" +colnum+ "&advtype=" +v1 + " target=_blank>\n";
 var dsrc ="<img src=http://ad.focus.com.cn/advmgr/advcolumns/advimg.php?colid=" +colnum+ "&advtype=" + v1 + " border=0></a>\n";
 document.write(dhref);
 document.write(dsrc);
}