摘要
Received 23 November 2012 Received in revised form 13 December 2012 Accepted 18 December 2012 Available online 20 January 2013
Received 23 November 2012 Received in revised form 13 December 2012 Accepted 18 December 2012 Available online 20 January 2013
基金
financially supported by the National Natural Science Foundation of China(Nos.20931003 and 21071068)
the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China(No. J1103307)