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. 2021 Jan 21;8:5. doi: 10.1186/s40779-021-00300-z

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© The Author(s) 2021

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

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Fig. 4 — The analysis of keywords in publications on HS. a Mapping of the keywords in the area of HS. The words were divided into three clusters in accordance with different colors that were generated by default, specifically, basic research (left in red), clinical research (up in green), and epidemiological research (right in blue). The large icon indicates the keywords that appeared at a high frequency; b The distribution of keywords is presented according to the average time of appearance, with the blue representing an early appearance and the yellow indicating keywords that have appeared more recently. The smaller the distance is between two keywords, the greater the frequency of their co-occurrences