supported by the Natural Science Foundation of Hainan(114005);the Natural Science Foundation of the Hainan High Education Institutions of China(Hjkj2012-19)
supported in part by 985 Project(212011);973 Project(2011CB808000);the National Natural Science Foundation of China(11131003);the Specialized Research Fund for the Doctoral Program of Higher Education(20100003110005);the Fundamental Research Funds for the Central Universities