$re = '/(\([^(]*\))/mi';
$str = 'NULL ({ / / }) Regina ({ 4 p1 p2 / / }) Shueller ({ 5 p1 p2 / / }) works ({ / / }) for ({ / / }) Italy ({ 14 / / }) \'s ({ 15 / / }) La ({ 16 / / }) Repubblica ({ 17 / / }) newspaper ({ 18 / / }) . ({ 38 / / })';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php