Funding for this research was provided by:
Natural Science Foundation of Heilongjiang Province (No. F201416)
Research and Development Project of Applied Technology in Harbin (No.2016RAXXJ071)
Text and Data Mining valid from 2019-08-23
Received: 27 October 2017
Accepted: 6 August 2019
First Online: 23 August 2019
Ethics approval and consent to participate
: Not applicable.
: Not applicable.3
: The authors declare that they have no competing interests.