EndNote 21 can automatically search for full-text to attach PDFs and links. While EndNote cannot find all full-text materials at this time, this feature may save you time.
Automatically invoke Find Full Text on newly-imported references
It may seem like a good decision to check this box. However, it can really slow the import process, especially when you are importing a large number of references from a database (e.g., PubMed). Also, attaching PDFs for every reference in your library will take up memory and space since PDFs files are not necessarily small files. It can be more useful to use your Endnote library as a place to screen abstracts, and then attach full-text PDFs of the articles you've determined you want to read in full.
The LRC Reference staff will be happy to assist you with your EndNote questions.
You may also contact EndNote Technical Support: