Funding for this research was provided by:
National Major Science and Technology Projects of China (No.2015GKS-072/139, No.2009ZX09103-624)
Text and Data Mining valid from 2019-09-06
Received: 7 March 2019
Accepted: 28 August 2019
First Online: 6 September 2019
Ethics approval and consent to participate
: The study design was approved by the appropriate ethics review board. We have read and understood your journal’s policies, and we believe that neither the manuscript nor the study violates any of these.
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: The authors declare that they have no competing interests. The authors alone are responsible for the content and writing of the paper.