摘要
Received 15 November 2012 Received in revised form 5 December 2012 Accepted 12 December 2012 Available online 20 January 2013
Received 15 November 2012 Received in revised form 5 December 2012 Accepted 12 December 2012 Available online 20 January 2013
基金
the financial support from the National Natural Science Foundation of China(Nos.21005006 and 21127007)
the Fundamental Research Funds for the Central Universities(Nos.06108101,06199019 and 06199024)