Funding for this research was provided by:
National Natural Science Foundation of China (41671095, 51761135024, 61631011)
National Key Research and Development Program of China (2017YFE0100700)
Financial Fund Planning Project in Inner Mongolia (2018-ZME-KJXT-14)
Article History
Received: 11 December 2015
Accepted: 6 July 2018
First Online: 17 July 2018