php preg_replace正则表达式除去<a>

$content = '<br><a target="_blank" href="/redirect/http%3A//www.ctdisk.com/u/1227383">http://www.ctdisk.com/u/1227383</a>
</td>';

$content = preg_replace('/<a\s+.*?>(.*?)<\/a>/i', '${1}', $content);

去除所有链接

替换所有 class="innerlink" 的 a 标签:
$content = preg_replace('/<A\s+class=innerlink.*?>(.*?)<\/A>/i', '${1}', $content); 

严格一点，替换 class="innerlink" 且 title=链接文字 的标签:
$content = preg_replace('/<A\s+class="?innerlink"?.*?\stitle="?(.*?)"?.*?>\s*(\1)\s*<\/A>/i', '${1}', $content);