http://msdn.microsoft.com/zh-cn/library/bb882581.aspx
DateTime dt = DateTime.Now;
Console.WriteLine(dt.ToString("yyyy-MM-dd HH:mm:ss fff"));
string dateString = "2009-08-12 12:34:56.567";
DateTimeOffset dateOffsetValue = DateTimeOffset.Parse(dateString);
Console.WriteLine(dateOffsetValue.ToString("yyyy-MM-dd HH:mm:ss fff"));
DateTime dt2 = DateTime.Parse("2009-08-12 12:34:56.567");
Console.WriteLine(dt2.ToString("yyyy-MM-dd HH:mm:ss fff"));
Console.ReadKey();
DateTime.Now.ToString("yyyyMMddhhmmss")+ DateTime.Now.Millisecond.ToString()