Text and Data Mining valid from 2019-05-18
Received: 16 February 2019
Accepted: 15 April 2019
First Online: 18 May 2019
Ethics approval and consent to participate
: The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki. Patients provided a written consent for the study, and the ethical approval was obtained from the Gansu provincial Hospital Research Ethics Committee.
: Not applicable.
: The authors declare that they have no competing interests.
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