. 2021 Jul 30;8:648397. doi: 10.3389/fmed.2021.648397
Copyright © 2021 Xu, Jiang, Li, Li, Geng, Chen, Hu, Shen, Wang, Fang, Wang, Luo, Tu, Hu, Ding, Teng and Xu.
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Figure 1.
Study flowchart.