The purpose of scholarly journals is to share findings, ideas, and discoveries within a community of specialized scholars. It is in these journals that the cutting edge discoveries, ideas, and developments of every field are first published. Many of these journals are peer-reviewed, meaning that every article that is deemed a possible candidate for publication is read by two or three recognized scholars in the field, who critique not only the writing but the importance and usefulness of the information presented.
Typically, these journals are only open to people doing original work in the field. Within each discipline there is a hierarchy of journals, with the top journals only publishing the most important and exciting work, and/or only publishing work produced by recognized scholars and/ or laboratories, and the smaller journals typically publishing good but less groundbreaking work. Guidelines for publication in these journals are listed in one issue a year, or can be obtained online; a potential writer for one of these publications is recommended to be familiar and comfortable with the typical level of discourse, tone, style, subjects, etc.
The best place to find out more is to investigate individual disciplines are Writing Across the Curriculum sites.