I have found MEDLINE to be a search engine with the most abstracts, dating back up to 20 years ago and also from diversity of sources, while individual medical journals on-line usually just have past few years of their articles.
Medline's search interface has several default settings that may not prove to be the best for you. If you are searching for a general topic for which you will get several thousand abstract titles as a result of your query, or you are looking just for the latest papers, you can keep their default setting "last two years only". If you are interested in more than 2 last years, or your search does not get you sufficient number of titles, go ahead and disable this setting. The other setting that I recommend changing is the number of titles displayed per page. Default for this is 10, but since you need to wait between each page( and lost data page comes up quite frequently ), you can save a lot of time if you change this setting to 50.
Once you get your first 50 titles, you can go ahead and click on the ones you are interested in one by one. The better way is to check-mark all interested titles( or click on "select all" ), and then download them all in one take( you save considerable amount of time this way ).
Advanced search page gives you the opportunity to define the range of publication years and to request up to 200 titles( recommended ).
Happy surfing!