Funding for this research was provided by:
National Natural Science Foundation of China (71573229)
Text and Data Mining valid from 2018-11-09
Received: 7 August 2018
Accepted: 29 October 2018
First Online: 9 November 2018
Ethics approval and consent to participate
: This study was approved by the institutional review board of Zhejiang University School of Public Health.
: Not applicable.
: The authors declare that they have no competing interests.
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