Funding for this research was provided by:
Education Department of Sichuan Province (14ZA0269)
Yibin University (2013QD02)
Young Scientists Fund (61201266)
Article History
Received: 21 October 2018
Accepted: 11 January 2019
First Online: 11 February 2019
Competing interests
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.