function novajanela(url,janela, altura, largura)
  {
  window.open(url,janela,"toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,copyhistory=no,top=0,left=0,screenY=0,screenX=0,width="+largura+",height="+altura);
  }