Funding for this research was provided by:
National Natural Science Foundation of China (61801144, 61871348, 61671184)
Natural Science Foundation of Shandong Province (ZR2018PF001, ZR2014FP016)
Fundamental Research Funds for the Central Universities (HIT.NSRIF.201720, HIT.NSRIF.2016100)
Text and Data Mining valid from 2019-03-19
Received: 30 August 2018
Accepted: 21 February 2019
First Online: 19 March 2019
: The authors declare that they have no competing interests.
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