Fig. 7

Theme evolution and thematic map. A Keyword evolution analysis of m6A methylation and viral infection in different time periods from 2000 to 2020. The nodes represent the main research topics generated from the co-occurrence network analysis, and the number of keywords contained in each node is represented by the size of the corresponding node. Time slices from adjacent segments sharing the same keyword are connected by streamlines, the width of which is proportional to the number of keywords. B Conceptual structure map. The area marked in red indicates the first largest category of keyword clusters, and the blue area indicates a small category. Each dot represents a keyword, and its distance means how often they appear in the article. The proximity of a keyword to the center point represents its popularity in the research field. C Thematic map. The horizontal axis represents centrality, and the vertical axis represents density. The first quadrant (upper right) is motor themes, implying both important and well developed. The second quadrant (upper left) is highly developed and isolated themes, indicating that there has been good development, but not important for the current research field. The third quadrant (lower left) is emerging or declining themes, indicating marginal themes that may not have a good development. The fourth quadrant (lower right) is basic and transversal themes, which are important to the field but have not been well developed (generally basic concepts)