function checka()
{
  if (document.searcha.namea.value=="")
  {
    alert("ÇåÊäÈë¹Ø¼ü×Ö");
	document.searcha.namea.focus();
	return false;
  }
  if (document.searcha.selecta.value=="google_site"){
       window.open("http://www.google.com/search?q="+searcha.namea.value+"&ie=GB2312&hl=zh-CN&lr=","google_site");
	   return true;
  }
    if (document.searcha.selecta.value=="baidu_site"){
            window.open("http://www1.baidu.com/baidu?tn=114comcn&word="+searcha.namea.value,"baidu_site");
	   return true;
  }
    if (document.searcha.selecta.value=="yahoo_site"){
     window.open("http://cn.search.yahoo.com/search/cn?stype=site&p="+searcha.namea.value,"yahoo_site");
	   return true;
  }
    if (document.searcha.selecta.value=="sina_site"){
 window.open("http://search.sina.com.cn/cgi-bin/search/search.cgi?_searchkey="+searcha.namea.value+"&_ss=sina&enter=%CB%D1%CB%F7","sina_site");
	   return true;
  }
    if (document.searcha.selecta.value=="netease_site"){
 window.open("http://nisearch.163.com/search.php?q="+searcha.namea.value+"&url=http%3A%2F%2Fnisearch.163.com%2Fsearch.php&source=163&word=%C0%EE%B0%D7","netease_site");
	   return true;
  }
    if (document.searcha.selecta.value=="sohu_site"){
    window.open("http://site.search.sohu.com/website.jsp?key_word="+searcha.namea.value+"&page_index=0","sohu_site");
	   return true;
  }

}