function isNull( str ){
	if ( str == "" ) return true;
	var regu = "^[ ]+$";
	var re = new RegExp(regu);
	return re.test(str);
}

function checkForm(objFrm){
	var objSel=objFrm.search_type;
	var selIndex=objSel.selectedIndex;
	var selVal=objSel.options[selIndex].value;
	var txtKeyword=objFrm.keyword.value;
	
	if (selVal == 0){
		alert("请选择检索入口！");
		objSel.focus();
		return false;
	}else{
		if (isNull(txtKeyword)){
			alert("请填写检索内容！");
			objFrm.keyword.focus();
			return false;
		}else{
			return true;
		}
	}
}