AJAX异步方式请求比同步方式请求HTTP头部多一个 X-Requested-With
直接影响 C#中 Request.IsAjaxRequest() 的判断，同步方式判断为false
当然也可以自已写。
public static bool IsAjaxRequest(this HttpRequestBase request)
{
if (request == null)
{
throw new ArgumentNullException("request");
}
return request["X-Requested-With"] == "XMLHttpRequest" || (request.Headers != null && request.Headers["X-Requested-With"] == "XMLHttpRequest");
}