public static string replaceImgUrl(string html)
{
if (html == null)
return "";

System.Text.RegularExpressions.Regex regex = new System.Text.RegularExpressions.Regex(@"\<img[^\>]+\>", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
html = regex.Replace(html, ""); //过滤frameset
return html;
}