Funding for this research was provided by:
Jilin Provincial Development and Reform Commission (2017c033-1)
National defense research frontier exploration project of The Northeast Normal University
Text and Data Mining valid from 2018-06-25
Received: 5 April 2018
Accepted: 30 May 2018
First Online: 25 June 2018
: The authors declare that they have no competing interests.
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