Funding for this research was provided by:
Natural Science Foundation of National Medical Professional Degree Graduate Education Steering Committee (B2-YX20180203-01)
Shandong Provincial Postgraduate Education Quality Improvement Plan for 2018 (SDYAL18047)
Received: 21 September 2019
Accepted: 26 May 2020
First Online: 11 September 2020
Ethics approval and consent to participate
: Not applicable. This study does not involve human participants, human data or human tissue.
: Not applicable. This study does not involve individual data.
: The authors declare that they have no competing interests.