Funding for this research was provided by:
National Natural Science Foundation of China (61672272, 61303131)
National Natural Science Foundation of China (60973040)
Educational Reform Project of Fujian (FBJG20170055)
Article History
Received: 28 February 2017
Revised: 24 November 2017
Accepted: 27 December 2017
First Online: 24 January 2018