Funding for this research was provided by:
National Natural Science Foundation of China (11601048)
Natural Science Foundation of Chongqing (cstc2016jcyjA0181)
the Science and Technology Research Program of Chongqing Municipal Education Commission (KJQN201800533)
Natural Science Foundation of Chongqing Normal University (16XYY24)
Article History
Received: 29 January 2019
Accepted: 10 June 2019
First Online: 26 June 2019
Ethics approval and consent to participate
: Not applicable.
: The authors declare that they have no competing interests.
: Not applicable.