Journal impact factor is a data in the published journal citation report. It is the total number of citations of academic papers published by a journal in the last two years of this reporting year divided by the total number of papers published by this journal in these two years. This is also an internationally accepted periodical evaluation index.

First of all, we need to know the specific query address when querying the impact factors. The query addresses of foreign periodicals and Chinese periodicals are different.

1. To query the impact factors of foreign periodicals, you can use JCR in the Science foreign language database Web, in which JCR science edition is used to query natural science periodicals and JCR social science edition is used to query humanities and social science periodicals.

2. To query the influencing factors of Chinese journals, you can use the Comprehensive Citation Report of China Academic Journals (edited by Wan Jinkan, Science Press) jointly published by China Academic Journals (CD-ROM Edition) and China Scientific Literature Metrology and Evaluation Center. Readers in need should go to the library consulting department for enquiry.

The impact factors given by JCR and the above indicators play a very important role. Specifically, they have various practical values for the following types of personnel.

1. Librarians make literature collection plans and budgets, and recommend excellent periodicals to readers.

2. Editors should know and master the situation of their own periodicals, and make effective editing plans and publishing targets.

3. Publishers master and monitor publishing trends, seize publishing opportunities and make new publishing decisions.