Funding for this research was provided by:
Scientific Research Project for Universities in Ningxia, China (NGY2018-71)
Natural Science Foundation of Ningxia, China (2018AAC03094)
The Third Batch of Ningxia Youth Talents Supporting Program (TJGC2018084)
Received: 18 October 2019
Accepted: 24 September 2020
First Online: 18 November 2020
Ethics approval and consent to participate
: The whole protocols study with students was fully approved by the scientific committee of Ningxia Medical University. All the students participated in the protocols were informed and consent for future use of questionnaire data. Written consent from the students of the university was given by signing a form.
: Not applicable.
: The authors declare that there are no conflicts of interest.