public static string GetArticleList(string topicId, int startIndex, int maximumRows, string sortExpressions)
{
Guid idTopic = new Guid(topicId);
Topic topic = (Topic)TopicList.Search(o => ((Topic)o).Id == idTopic);
ArticleList = ArticleCollection.GetArticleCollection(topic);
System.Web.Script.Serialization.JavaScriptSerializer js = new System.Web.Script.Serialization.JavaScriptSerializer();
return(js.Serialize(ArticleList.GetSegment(startIndex, maximumRows, sortExpressions)));
}