function sito_param_get(my_param) {
   param_value=null;
   if(window.location.search.length!=0) {
      url_param = window.location.search.slice(1,window.location.search.length);
      tab_url_param = url_param.split('=');
      if(tab_url_param[0]==my_param) {
         param_value = tab_url_param[1];
      }
   }
   return param_value;
}