Funding for this research was provided by:
National Natural Science Foundation of China (81401156, 81602334)
Text and Data Mining valid from 2018-05-30
Received: 14 March 2018
Revised: 19 April 2018
Accepted: 2 May 2018
First Online: 30 May 2018
Ethics approval and consent to participate
: This study was conducted in accordance with the Declaration of Helsinki and was approved by the Research Ethics Committee of The Second Affiliated Hospital of Guangzhou Medical University (File no. 2014013).
: The authors declare that they have no competing interests.
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