<script language="javascript">
                    var checks = document.getElementsByName("urlcheckbox");
                    function checkOthers(){
                          var b = false;
                          for(var i = 0; i < checks.length; i++) {
                            if(checks[i].checked == false) {
                              checks[i].disabled == true;
                            }
                          }
                    }
                </script>