Funding for this research was provided by:
National Natural Science Foundation of China (11871302)
National Natural Science Foundation of China (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.