Funding for this research was provided by:
the China Postdoctoral Science Fund (2018M631383)
The Humanities and Social Science Research Project of the Ministry of Education (14YJCZH069)
Science and technology project of the Chongqing Municipal Education Committee (KJ1600622)
Chongqing Federation of Social Sciences (2017YBGL147)
Article History
Received: 30 June 2018
Accepted: 13 February 2019
First Online: 15 April 2019
Compliance with ethical standards
:
: The authors declare that they have no competing interests.