Submitted on: 08 July 2013.
Revised on: 10 August 2013.
Accepted on: 27 August 2013.
NULL
http://reply.papertrans.cn/3/208/20726/20726-32.png
Submitted on: 07 November 2010.
Revised on: 17 December 2010.
Accepted on: 26 December 2010.
NULL
Submitted on: 27 September 2003.
Revised on: 31 October 2003.
Accepted on: 07 November 2003.
NULL
http://reply.papertrans.cn/3/208/20726/20726-35.png
http://reply.papertrans.cn/3/208/20726/20726-36.png