国家自然科学基金项目61573265,61203037,51305321;新加坡教育部Tier 1科研基金2014-T1-001-147;新加坡教育部Tier 2科研基金MOE 2015-T2-2-049资助.Supported by the National Natural Science Foundation of China61573265,61203037,51305321;the Academic Research Fund Tier 1 by Ministry of Education in Singapore2014-T1-001-147;the Academic Research Fund Tier 2 by Ministry of Education in SingaporeMOE2015-T2-2-049