Funding for this research was provided by:
Humanities and Social Sciences Foundation of Ministry of Education, China (18YJC890041)
Natural Science Foundation of Hunan Province, China (2018JJ3118)
Article History
Received: 22 April 2019
Accepted: 15 July 2019
First Online: 7 August 2019
Compliance with ethical standards
:
: The authors declare no conflicts of interest.
Free to read: This content has been made available to all.