Funding for this research was provided by:
National Natural Science Foundation of China (31771228)
Federation for the Humanities and Social Sciences (17JJD190001)
the Projects of Key Institute of Humanities and Social Sciences, MOE (16JJD190001)
Guangdong Youth Research Project (2018WT005)
Article History
First Online: 23 January 2020
Compliance with Ethical Standards
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: The authors declare that they have no conflict of interest.