$(document).ready(function () {
  setInterval("lien()", 300);
});
var ancre = null;
function lien(){ 
  if (document.location.hash.length >= 3 && ancre != document.location.hash){  
      $("#blocContenu").fadeOut(300, function () {
      var contenu = document.location.hash.substr(1,document.location.hash.length);
      $("#preBlocContenu").load("page_"+contenu+".php", {pos: 2}, function () {
        $("#blocContenu").fadeIn(300);
      });
    });
  ancre = document.location.hash;
  }
}