Funding for this research was provided by:
National Social Science Foundation of China (19AJY001)
Postdoctoral Research Foundation of China (2020T130393)
Soft Science Research Program in Shaanxi Province (2021KRM156, 2021KRM086)
Fundamental Research Funds for the Central Universities (GK202103117, GK202103118)
Article History
Received: 5 September 2020
Accepted: 27 June 2021
First Online: 8 July 2021