Funding for this research was provided by:
National Natural Science Foundation of China (31471820)
Natural Science Foundation Project of Chongqing (cstc 2015jcyjA80037)
Fundamental Research Funds for the Central Universities (106112017CDJQJ298831)
Article History
Received: 29 March 2018
Revised: 9 April 2018
Accepted: 12 April 2018
First Online: 1 May 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with human participants performed by any of the authors.