There are at least two reasons you might want to find dissertations: 1) to find out whether the research project you have chosen for your graduate work has already been done, and 2) to look up a dissertation to which you have found a reference. You will often find dissertation citations when you are searching CINAHL.
UNB Libraries provides access to the full text of all the PhD dissertations and Master's theses granted by over 1000 universities, mostly in North America, since 1997. This includes over 7300 in Nursing alone. The same "Digital Dissertations" database also provides indexing and abstracting, but not fulltext, for dissertations and theses from 1996 back to 1861. To access the database, go to the UNB Libraries homepage at http://www.lib.unb.ca, go to Indexes and Abstracts from the e-Resources menu at the top of the page, and choose the title "Digital Dissertations (with some fulltext)".
As well as the familiar Keyword, Author, and Title, this database lets you search for dissertations by School, Adviser and Degree. You can combine two or more fields in on search. There is also a searchable Subject field, which classifies theses by academic area. You can use the Browse function to restrict your search to a particular Subject if you wish, or use the Subject Tree to search within several subjects at once. You can also limit your search by date range, consult the School Index, and combine earlier searches using the Search History screen.
Recently, a number of dissertations, but not Master's theses, have been added to the ProQuest Nursing journal collection. For subject searching, Digital Dissertations is better because it is more comprehensive. On the other hand, there is full text available back to 1990, so if you have a citation to a Nursing dissertation between 1990 and 1997, it is worth checking there for it. To get to the ProQuest journal collection, go to the UNB Libraries home page, click on e-Journals in the e-Resources menu, and choose ProQuest Nursing from the "Browse e-Journal Collections" list. Then choose "ProQuest Nursing Search" at the next page. You can then search by keyword, author, title etc. Dissertation results will appear under a separate Dissertations tab. If full text is available, it can be downloaded immediately from the site.
Another place to look for full-text theses is Library and Archives Canada's Theses Canada Portal, which allows you to "access and search for free the full text electronic versions of Canadian theses and dissertations that were published from the beginning of 1998 to August 31, 2002". The portal is free on the Internet at http://www.collectionscanada.ca/thesescanada/index-e.html.