////////////////////////////
           string inputstr = "@{AbcD},@{bbbb},@{ABcd}";
            string pmType = "@";
            string regTxt = (pmType + "http://s*//{//s*" + "abcd" + "http://s*//}").Replace("(", "http://(").Replace(")", "http://)");
            //string regTxt = (pmType + "http://s*//{//s*" + "aaaa" + "http://s*//}").Replace("(", "http://(").Replace(")", "http://)");
           // string regTxt = @"@/s*/{/s*aaaa/s*/}";
           // string regTxt = @"@/s*/{/s*aaaa/s*/}/gi";
            inputstr = Regex.Replace(inputstr, regTxt, "CCC", RegexOptions.IgnoreCase | RegexOptions.Compiled);
///////////////

         對于小文本不使用 RegexOptions.Compiled；