Funding for this research was provided by:
National Natural Science Foundation of China (81673146)
Received: 17 September 2020
Accepted: 2 December 2020
First Online: 6 January 2021
Ethics approval and consent to participate
: The study protocol and instruments were reviewed and approved by the Peking University Institutional Review Committee. Ethical approval identification code is IRB00001052-16071. The study was conducted according to the guidelines of the Declaration of Helsinki. Prior to the study, all participants read and signed the informed consent form.
: Not applicable.
: The authors declare that they have no competing interests.