Text and Data Mining valid from 2018-12-01
Received: 29 May 2018
Accepted: 26 November 2018
First Online: 5 December 2018
Ethics approval and consent to participate
: The Institutional Review Board of Peking Union Medical College Hospital approved this study and written informed consent was obtained from the participants.
: Not applicable.
: The authors declared that they had no competing interests.
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