function showKnowItem( item_id ) {
        if( !item_id ) return false;
        if( !$('#know_item_title' + item_id ).hasClass('know_item_active') ) {
          $('#know_item_title' + item_id ).addClass('know_item_active');
          $('#know_item_content' + item_id ).show();
        } else {
          $('#know_item_title' + item_id ).removeClass('know_item_active');
          $('#know_item_content' + item_id ).hide();
        }
      }
      $(document).ready( function() {
        if( window.location.hash ) {
          showKnowItem( window.location.hash.substr(1) );
        }
      });