function wzdh_search(keyword) {
    table = {};

    if (keyword == '') {
        last_keyword = '';
        return null;
    }

    var s = document.getElementsByTagName('a');
    var length = s.length;
    var result = [];
    var href   = ''

    for (var i= 0; i < length; i++) {
        href = s[i].getAttribute("href");
        if (s[i].getAttribute("s") == "1" && !table[href] && s[i].innerHTML.toLowerCase().indexOf(keyword) != -1) {
            result.push(s[i]);
            table[href] = true;
        }
    }

    return result;
}