For nearly all scientific articles, abstracts are available at no charge. Some publishers have a policy of charging a fee for all articles, some will charge for recent articles but make older ones available at no cost.
Elsevier (http://www.elsevier.nl/) says that they are "A world leading, multiple-media publisher of scientific, technical and health information products and services, with 7,000 employees in 99 locations around the globe." For some articles a paid subscription is required.
Many times an article can be found using a search engine such as Google (http://www.google.com) and searching for as much information as is known. For example the exact title, a partial title and author, or the author, date and a keyword, for example Crohn's or paratuberculosis.