Impact factor is an important index to measure the influence of a journal, which refers to the frequency of articles cited in a particular year or period. The formula for calculating the impact factor is: IF= (number of citations this year)/(number of articles this year).

If you want to query the impact factors of a literature or periodical, you can install the plug-in scholarship on the browser, which can automatically load the impact factors of PubMed periodicals to help users filter useful periodicals.