function init(){
var elements =document.getElementsByName('time_status');
var butt =document.getElementsByName('sign_button');

for (var i = 0; i < elements.length; i++) {
if(elements[i].innerHTML != 'свободно')
{
butt[i].style="";
butt[i].style.visibility = "hidden";
butt[i].style.display="none";
 }
}
}

 window.onload = init;