Web of Science Core Collection, one of the most authoritative bibliographic databases, is widely used in academia to track high-quality research. This database has begun to index online-first articles since December 2017. This new practice has introduced two different publication dates (online and final publication dates) into the database for more and more early access publications. It may confuse many users who want to search or analyze literature by using the publication-year related tools provided by Web of Science Core Collection. By developing custom retrieval strategies and checking manually, this study finds that the "year published" field in search page searches in both online and final publication date fields of indexed records. Each indexed record is allocated to only one "publication year" on the left of the search results page which will inherit first from online publication date field even when the online publication date is later than the final publication date. The "publication year" field in the results analysis page and the timespan "custom year range" field in the search page have the same function as that of the filter "publication year" in search results page. The potential impact of the availability of two different publication dates in calculating bibliometric indicators is also discussed at the end of the article.

中文翻译：

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时间问题：Web of Science 核心合集中的发表日期

Web of Science 核心合集是最权威的书目数据库之一，在学术界被广泛用于跟踪高质量的研究。该数据库自 2017 年 12 月起开始索引在线第一篇文章。 这种新做法在数据库中引入了两个不同的出版日期（在线和最终出版日期），以便越来越多的早期访问出版物。它可能会让许多想要使用 Web of Science 核心合集提供的出版年份相关工具搜索或分析文献的用户感到困惑。通过开发自定义检索策略并手动检查，本研究发现搜索页面中的“出版年份”字段在索引记录的在线和最终出版日期字段中进行搜索。每个索引记录只分配给一个“出版年” 在搜索结果页面的左侧，即使在线发布日期晚于最终发布日期，它也会首先继承在线发布日期字段。结果分析页面中的“出版年份”字段和搜索页面中的时间跨度“自定义年份范围”字段与搜索结果页面中过滤“出版年份”的功能相同。文章末尾还讨论了在计算文献计量指标时使用两个不同出版日期的潜在影响。检索页中的字段与检索结果页中的“出版年份”过滤器功能相同。文章末尾还讨论了在计算文献计量指标时使用两个不同出版日期的潜在影响。检索页面中的字段与检索结果页面中的“出版年份”过滤器功能相同。文章末尾还讨论了在计算文献计量指标时使用两个不同出版日期的潜在影响。