private string UnicodeToGB(string content)
        {
            Regex objRegex = new Regex("&#(?<UnicodeCode>[\\d]{5});", RegexOptions.IgnoreCase);
            Match objMatch = objRegex.Match(content);
            StringBuilder sb = new StringBuilder(content) ;
            while(objMatch.Success)
            {
                string code = Convert.ToString(Convert.ToInt32(objMatch.Result("${UnicodeCode}")),16);
                byte[]   array  = new  byte[2];   
                array[0]   =   (byte)Convert.ToInt32(code.Substring(2),16);   
                array[1]   =   (byte)Convert.ToInt32(code.Substring(0,2),16); 

                sb.Replace(objMatch.Value,Encoding.Unicode.GetString(array));

                objMatch=objMatch.NextMatch();
            }
            return sb.ToString();
        }