Funding for this research was provided by:
Tianjin Research Program of Application Foundation and Advanced Technology (13JCYBJC21500, 15JCYBJC54600)
Science & Technology Foundation for Selected overseas Chinese scholar, Bureau of personnel of China, Tianjin
Text and Data Mining valid from 2018-07-09
Received: 12 February 2018
Accepted: 3 July 2018
First Online: 9 July 2018
Ethics approval and consent to participate
: This retrospective study was approved by the ethics committee of the First People’s Hospital of Xianyang, and all procedures were performed in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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