Funding for this research was provided by:
National Natural Science Foundation of China (31470471, 31301878, 31300339 and 31272294)
Priority Academic Program Development of Jiangsu Higher Education Institutions
Natural Science Foundation of Jiangsu Province (SBK2016020667)
Innovation Program of Jiangsu Province for Graduate Students (KYLX_0715)
Cultivation Program for Excellent Doctoral Students of Nanjing Normal University
Text and Data Mining valid from 2018-04-03
Received: 7 December 2017
Accepted: 22 March 2018
First Online: 3 April 2018
: No ethics approval was required for this research.
: Not applicable.
: The authors declare that they have no competing interests.
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