Funding for this research was provided by:
National Natural Science Foundation of China (11871302, 11601048)
Natural Science Foundation of Chongqing (cstc2016jcyjA0181)
Qufu Normal Universit (BSQD20130140)
Chongqing Normal University (16XYY24)
Article History
Received: 26 March 2019
Accepted: 14 July 2019
First Online: 23 July 2019
Competing interests
: The authors declare that there is no conflict of interests regarding the publication of this paper.