From the homepage:
Science Fiction Studies is published three times a year (March, July, November) by SF-TH Inc. at DePauw University. The Science Fiction Studies website publishes abstracts of all articles, as well as the full texts of all reviews, historical documents, and selected essays appearing in the journal since its founding in 1973 by R.D. Mullen. Full texts of articles are posted only after an issue has been sold out.
The most recent issue, as of November 2023, is #151.
Please note the metadata of the DePauw University hyperlinks never references SFS, in case of confusion. Furthermore, you might be interested in the SFE article on SFS, although it’s outdated (last modified 2022).