Funding for this research was provided by:
National Natural Science Foundation of China (81573255)
Text and Data Mining valid from 2018-11-06
Received: 31 March 2018
Accepted: 3 October 2018
First Online: 6 November 2018
Ethics approval and consent to participate
: Because this dataset is within the public domain and all patient information is de-identified, the study has been granted an exemption from requiring ethics approval by Institutional Research Board of Harbin Medical University, and the informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.
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