Text and Data Mining valid from 2020-03-30
Received: 16 January 2020
Accepted: 23 March 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: This study was approved by the ethics committee of our university and strictly adhered to the tenets of the Declaration of Helsinki. In addition,all patients’ guardians signed an informed consent form before study.
: All the authors agree to the publication of this manuscript.
: The authors declare that they have no competing interests.