date_default_timezone_set('PRC');//设置时区
//设置起始时间
$five = strtotime(date("Y-m-d",time())." 19:00:00");
//设置结束时间
$seven = strtotime(date("Y-m-d",time())." 20:00:00");
if(time() > $five && time() < $seven){
    echo "正常操作";
}else{
    echo "禁止操作";
}