عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Today, Speed and coverage are two important factors that are considered by databases. In fact, a database in a particular subject area can be valid when a large percentage of the area covered by the thematic keywords and consequently it can provide most of the resources with the resources for that subject. The present study was conducted based on analytical - survey method with the main objectives of comparing Noormagz, Magiran and SID databases according to the rate of information, knowledge retrieval, and relevance of thematic vocabulary by free and controlled Keywords as well as Secondary objectives of comparing the coverage and overlap of these three databases of indexed journals in the field of information science and knowledge. All journals in the field of information and knowledge science are approved by the Ministry of Science, Research and Technology, according to the latest list of valid publications of this ministry in March 2016 , and key words taken from the articles in these journals were considered population of this research. Searching and comparing selected thematic keywords in each of the study databases indicated that there are a huge difference regarding free and controlled vocabulary retrieval of information and knowledge science in Noormagz database compared to the other two sites. In addition, studying the thematic relevance of research data showed that the ability of this database for receiving other related articles is more than two other databases. Although the titles of journals in Magiran database were more than those two databases and this database compared to two other databases was more update, the number of journals published in Noormagz database were more than others.