Funding for this research was provided by:
National Natural Science Foundation of China (81401238, 81330016, 81630038)
Text and Data Mining valid from 2018-07-27
Received: 26 April 2018
Accepted: 3 July 2018
First Online: 27 July 2018
Ethics approval and consent to participate
: This study has not directly involved humans, though is based on retrospectively analyzed pre-existing data.
: Not applicable.
: The authors declare that they have no competing interests.
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