Funding for this research was provided by:
National Natural Science Foundation of China (No. 91851106)
Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-DQC026)
Key Research Program of the Chinese Academy of Sciences (KFZD-SW-219-3)
Text and Data Mining valid from 2019-05-04
Received: 30 January 2019
Accepted: 25 April 2019
First Online: 4 May 2019
: The authors declare that they have no competing interests.
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