Funding for this research was provided by:
National Natural Science Foundation of China (71501062)
Shantou University (STU Scientific Research Initiation Grant (STF18011))
Key Projects of Philosophy and Social Sciences Research of Chinese Ministry of Education (19JZD021)
Article History
Received: 16 October 2018
Accepted: 30 October 2019
First Online: 13 November 2019
Compliance with ethical standards
:
: The authors declare that they have no competing interests.