Funding for this research was provided by:
National Natural Science Foundation of China (81473768)
Fundamental Research Funds for the Central Public Welfare Research Institutes (ZZKF08007)
Received: 16 July 2018
Accepted: 17 April 2019
First Online: 14 May 2019
Ethics approval and consent to participate
: This study was approved by the Chinese Ethics Committee of Registering Clinical Trials (reference: ChiECRCT-20140035).
: Not applicable
: The authors declare that they have no competing interests.
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