Funding for this research was provided by:
Social Sciences Research Project of Ministry of Education of China (17YJA630065)
Shandong Provincial Natural Science Foundation (ZR2017MG007)
Humanities, the Science and Technology Project of Colleges and Universities of Shandong Province (J16LN25)
Shandong Education Science Plan (ts201511045)
Article History
Received: 6 March 2020
Accepted: 29 July 2020
First Online: 9 August 2020
Compliance with Ethical Standards
:
: The authors declare that there is no conflict of interest regarding the publication of this paper.