Empirical evidence demonstrates that citations received by scholarly publications follow a pattern of preferential attachment, resulting in a power-law distribution. Such asymmetry has sparked significant debate regarding the use of citations for research evaluation. However, a consensus has yet to be established concerning the historical trends in citation concentration. Are citations becoming more concentrated in a small number of articles? Or have recent geopolitical and technical changes in science led to more decentralized distributions? This ongoing debate stems from a lack of technical clarity in measuring inequality. Given the variations in citation practices across disciplines and over time, it is crucial to account for multiple factors that can influence the findings. This article explores how reference-based and citation-based approaches, uncited articles, citation inflation, the expansion of bibliometric databases, disciplinary differences, and self-citations affect the evolution of citation concentration. Our results indicate a decreasing trend in citation concentration, primarily driven by a decline in uncited articles, which, in turn, can be attributed to the growing significance of Asia and Europe. On the whole, our findings clarify current debates on citation concentration and show that, contrary to a widely-held belief, citations are increasingly scattered.

翻译：实证证据表明，学术出版物获得的引文遵循优先依附模式，导致幂律分布。这种不对称性引发了关于利用引文进行科研评价的激烈讨论。然而，有关引文集中度的历史趋势尚未达成共识：引文是否越来越集中于少数文章？还是近年科学领域的政治与技术变革导致了更分散的分布？这场持续争论源于衡量不平等性的技术标准不明确。鉴于不同学科及不同时期引文实践的差异，必须考虑可能影响研究结果的多种因素。本文探讨了基于参考文献与基于引文的方法、未被引文章、引文通胀、文献计量数据库扩展、学科差异以及自引对引文集中度演变的影响。结果表明，引文集中度呈现下降趋势，其主要驱动力是未被引文章比例的降低——而这一降低又可归因于亚洲与欧洲日益增长的重要性。总体而言，我们的研究澄清了当前关于引文集中度的争论，并表明与普遍认知相反，引文正日益分散。