验证 Email

function check_email(Email)
{
 //if (!is_item_not_null(Email, "Email地址"))
  //return false;

 var pattern = /^([.a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(\.[a-zA-Z0-9_-])+/;
 flag = pattern.test(Email.value);
 if(!flag)
 {
  alert("您的Email地址填写不对。");
  Email.focus();
  return false;
 }
 else
  return true;
}