Citation metadata, including citation counts can be accessed through the Scopus/ScienceDirect API
Citation data to conduct research performance analysis. Additional information for the XML files can be found in the Web of Science XML Users Guide.
EBSCO databases allow researchers to download up to 25,000 citations at a time. This can only be done from a results screen and does not allow you to select individual articles. Note that this is only the citation information and not the full text of the articles. It does include abstracts, in most cases.
Follow these steps
The entire PubMed bibliographic database can be downloaded for local use or accessed via API. This is citation and abstract information only, not the text of the cited articles.
Learn more at the National Library of Medicine site.