国家自然科学基金项目51071058和51101041,中国博士后科学基金项目2013M541370和中央高校基本科研业务费专项资金项目HIT.NSRIF.2014001资助;National Natural Science Foundation of China.51071058 and 51101041;China Postdoctoral Science Foundation Funded Project2013M541370;Fundamental Research Funds for the Central UniversityHIT.NSRIF.2014001