Text and Data Mining valid from 2020-03-17
Received: 20 June 2019
Accepted: 10 February 2020
First Online: 17 March 2020
Ethics approval and consent to participate
: The present study was performed with the approval by the Ethics Committee of Yidu Central Hospital of Weifang. All the participants wrote informed consents before the sampling.
: Not applicable.
: The authors declare that they have no competing interests.