仅首字母
function mb_ucfirst($string, $encoding = 'UTF-8'){
$strlen = mb_strlen($string, $encoding);
$firstChar = mb_substr($string, 0, 1, $encoding);
$then = mb_substr($string, 1, $strlen - 1, $encoding);
return mb_strtoupper($firstChar, $encoding) . $then;
}