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The Nature Index has long made possible an analysis of research output trends from institutions or countries by broad subject area: four in the natural sciences (physical sciences, chemistry, biological sciences and Earth & environmental sciences) and, from 2022, in the health sciences. Research articles are assigned to these subject areas according to the discipline of the journal in which they appear , except for those that appear in one of the five multidisciplinary journals tracked by Nature Index, which are assigned at the article level.
From this week, the most recent data available on the Nature Index website — representing the latest 12-month window of uploaded articles — can also be browsed by more granular ‘topics’ that have been defined by analysing citation networks.
A team at Nature Research Intelligence used machine-learning methods to create the topic areas from networks of articles that either cite each other or are very similar to each other in terms of content. Each topic area at a certain level of granularity was labelled according to second-level subject categories used by the ANZSRC classification devised by the Australian Bureau of Statistics. Articles in these topic areas were then matched with those in the Nature Index database.
The largest three topic areas by article numbers in the database are in chemistry: physical chemistry; organic chemistry; and macromolecular and materials chemistry. The data show that China is the dominant producer of Nature Index research in each (see table below). Two health-sciences topics — clinical sciences and oncology/carcinogenesis — are fifth and sixth by article count, and are led by output from the United States.
Leading 10 topics by Nature Index article Count
| Topic | Nature Index article Count* | Leading country/territory |
|---|---|---|
| Physical chemistry | 4,344 | China |
| Organic chemistry | 4,193 | China |
| Macromolecular and materials chemistry | 3,834 | China |
| Condensed matter physics | 3,668 | China |
| Clinical sciences | 3,633 | United States |
| Oncology and Carcinogenesis | 3,496 | United States |
| Biochemistry and Cell Biology | 3,165 | United States |
| Inorganic chemistry | 2,455 | China |
| Particle and High EnergyPhysics | 2,392 | United States |
| Genetics | 2,247 | United States |
| *1 August 2023 to 31 July 2024 |
Data for more than 50 topic areas are available to browse on the Nature Index site, covering all ‘level two’ ANZSRC topics for which there are at least 100 Nature Index articles in the latest 12-month window.
Each available topic has its own dedicated data page showing the leading institutions and countries/territories in that topic by Share, the trend in article numbers for that topic in the past few years, and the leading institutional collaborations.
Leading topics can also be viewed as bar or bubble charts, allowing a quick comparison of the topics that tend to dominate in the database for each main Nature Index subject area. For instance, in Earth and environmental sciences, the three areas with most output are: climate change science; atmospheric sciences; and physical geography and environmental geoscience.
It is important to note that these topics, and the Nature Index data accompanying them, should not be compared with the fields of research that are the focus of some Nature Index supplements. These supplement topics are defined by using keywords to search for relevant articles, and as such can represent a more comprehensive view of a particular field of research.
Over the coming months, the Nature Index editorial team will periodically bring more insights — through our regular ‘data insights’ blogs — into the research trends seen in the citation topic areas.
