Scirus
Scirus was a comprehensive science-specific search engine, first launched in 2001. Like CiteSeerX and Google Scholar, it was focused on scientific information. Unlike CiteSeerX, Scirus was not only for computer sciences and IT and not all of the results included full text. It also sent its scientific search results to Scopus, an abstract and citation database covering scientific research output globally. Scirus was owned and operated by Elsevier.
In 2013 an announcement appeared, on the Scirus homepage, announcing the site's retirement in 2014:
By February 2014, the Scirus homepage indicated that the service was no longer running.