Funding for this research was provided by:
Natural Science Foundation of Jilin provincial science and Technology Department (20180101116JC)
Text and Data Mining valid from 2018-12-01
Received: 22 September 2018
Accepted: 11 December 2018
First Online: 27 December 2018
Ethics approval and consent to participate
: The experimental protocols were established according to the Declaration of Helsinki and approved by the Human Ethics Committee of Jilin University (Changchun, China). Written informed consent was obtained from the parents of each child.
: Not applicable.
: The authors declare that they have no competing interests.
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