function placehoder() 
		  {
				
				if(document.searchform.keys.value=='' || document.searchform.keys.value=='请输入关键字'){
					alert("请输入搜索关键词！");
					document.searchform.keys.focus();
					return false;
				} 
				var keyword=document.searchform.keys.value;
				if(document.searchform.search.value=="supply"){
					document.searchform.action="http://search.food36.com/results.php?keys="+keyword+"&type=供应";
				}else if(document.searchform.search.value=="product"){
					document.searchform.action="http://search.food36.com/results.php?keys="+keyword+"&type=采购";
				}else if(document.searchform.search.value=="company"){
					document.searchform.action="http://search.food36.com/results.php?keys="+keyword+"&type=招商";
				}else if(document.searchform.search.value=="product"){
					document.searchform.action="http://search.food36.com/resultp.php?keys="+keyword;
				}else if(document.searchform.search.value=="news"){
					document.searchform.action="http://search.food36.com/resultn.php?keys="+keyword;
				}
				return true;
		  }