php獲取今年本年第一天到現在的時間戳日期

$yearFirstDay  = date('Y-m-d: H:i:s' ,mktime(0, 0, 0, 1,1, date("Y")));
$nowDate  =        date('Y-m-d: H:i:s' ,mktime(23, 59, 59, date("m")  , date("d"), date("Y")));