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. 2021 Jun 22;12:687757. doi: 10.3389/fphar.2021.687757

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Copyright © 2021 Zhu, Hu, Deng, Tan, Qiu, Zhang, Ni, Lu, Wang, Li, Luo, Huang, Xiao, Liu, Li, Shang and Wen.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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| (A) The top ten highest frequency keywords extracted by using “Keywords Plus” from the WoSCC database via the biblioshiny app (B) Cluster visualization of the keyword co-occurrence network among the 50 main keywords via the biblioshiny app, presented in a sphere network layout.