Text and Data Mining valid from 2020-01-08
Received: 12 May 2019
Accepted: 22 December 2019
First Online: 8 January 2020
Ethics approval and consent to participate
: The First Affiliated Hospital ethics committee (Xi’an, Shaanxi) reviewed the research proposal and granted insurance. Written informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interest.