The IOP Science collection is used to search for and read articles from over 70 scientific and professional journals and some conference proceedings from the non-profit Institute of Physics (IOP) Publishing. Topics covered include physics, astronomy and astrophysics, mathematics, measurements, materials, electronics, computer science, and related fields in technology, medicine, biology, and chemistry. Accessibility of full-text articles varies; in some cases, journals are available from 1923 onward.