Funding for this research was provided by:
National Natural Science Foundation of China (71874005)
Article History
Received: 28 January 2020
Accepted: 22 May 2020
First Online: 26 May 2020
Ethics approval and consent to participate
: The ethics application for collecting data on human subjects was approved and updated annually by Peking University’s Institutional Review Board. All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.