function op(str,nome) {

x=(screen.width-660)/2
x1=x*6
y=((screen.height-540)/2)-20
y2=540
window.open(str,nome,'left='+ x +',top='+y+',width='+ 680 +',height='+ y2 +',resizable=yes,status=no,location=no,toolbar=no,scrollbars=yes');

}