Funding for this research was provided by:
National Natural Science Foundation of China (21675131, 21273174)
Natural Science Foundation of Chongqing (CSTC-2015jcyjB50001)
Article History
Received: 10 April 2019
Accepted: 19 May 2019
First Online: 13 June 2019
Compliance with ethical standards
: The authors declare that they have no competing interests.