如果在一段字符串文本中得到所有中文字符的话,可以使用下边程序来实现。 

public static string GetChineseWord(string oriText)
{
    string x = @"[\u4E00-\u9FFF]+";
    MatchCollection Matches = Regex.Matches(oriText, x, RegexOptions.IgnoreCase);
    StringBuilder sb = new StringBuilder();
    foreach (Match NextMatch in Matches)
    {
        sb.Append(NextMatch.Value);
    }
    return sb.ToString();
}