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. 2022 Jul 1;9:925369. doi: 10.3389/fmed.2022.925369

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Copyright © 2022 Liu, Zhang, Hu, Chen, Kong, Yao, Cong, Zuo, Wang, Li and Wei.

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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Network visualization map of citations by COVID-19 patents. (A) Citation network illustrating the evidence sources cited in 117 recommendation patent documents. The larger the circle is, the more frequently the patents received citations. Lines represent the citation direction. The force-directed layout algorithm of “Fruchterman Reingold” by Gephi is used to make the network distribution. Different circle colors indicate different technologies. (B) The main path from the typical key-route citation weighted with the top 10 patents of citation out-degree. In the visual analysis of the main path based on patent citation, time was added to the technology trajectory calculated by Gephi software, which clearly shows the research focus and direction of this field in different time periods.