Scholarly sources, which are normally published in journals, as book chapters, or in conference proceedings, usually cover specific topics at a fairly deep level. In Biology, scholarly sources are usually journal or research articles. Many research articles you will read concern a single experiment, case study, or point of data gathering on a topic. Review articles, which are less common, summarize the current research on a topic.
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A scholarly database organizes the best quality, most relevant information for a field or discipline in one place so it can be searched. Because there is so much scholarly research and so many different fields, databases specialize in which kinds of information or tools they provide.
Scholarly databases take into account the important publications and research methods of a field or discipline. The database helps you make choices about which articles you want to see - by subject, dates of publication, overall topic, and more. Google and Google Scholar, while vast, do no quality control on the content they provide or give you good tools to narrow your focus.
Web of Science is a powerful scientific database. Use the filters on the side of your search results to find review articles, which will summarize current research. The filters on the top of the results will help you find the most relevant, mostly recently published, or the most heavily cited articles. Heavily cited articles are usually important works on a topic.
PubMed is the best human subjects and health topics database. You can use the filters of your search to select for review articles, which summarize current research, patient population type, and the most recent publications.
Compendex is a database that focuses on engineering. This database is useful for finding device, materials, and intervention information rather than biological topics.