There are a number of ways that journals are published which will determine if you can freely access the articles that they contain online:
CORE is a not-for-profit service which provides access to the world’s largest collection of open access research papers, collecting and indexing research from repositories and journals Search Core
To find journals that make all full text content available to anyone use the Directory of Open Access Journals – this listing covers free, full text, quality controlled scientific and scholarly journals.
For journals that make some of the articles available to anyone - try going to the journal or publishers webpage and looking through the contents list to see which articles are available as to anyone as Open Access (these may have an open padlock icon beside them)
Example of a journal which makes the back issues freely available:
Journal of the MBA - Full-text of back issues 1887-1961
Repositories have a key role to play, as they both enable open access, and help universities, colleges and other organisations manage the intellectual output of their researchers.
This list is not comprehensive and you may find repositories for other research centres, universities and organisations through an internet search. If you need any help with finding information please contact the library libenqs@soton.ac.uk