$re = '/@([a-z]|-|[0-9])+\/([a-z]|-|[0-9])+/m';
$str = 'Lorem Ipsum i-s simply @dummy/text of the printing and typesetting industry. Lorem Ipsum has been the industry\'s @nAme/iNValid text ever since @the/1500s, when an @unknown//printer took a @galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also/the leap @into/electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets/containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum';
preg_match_all($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