According to the vendor; ScienceDirect "tutorials are available in a text version and available to users without Javascript. There is a "white" link at the bottom of the tutorial page for the assistance devices for textual version of the tutorial. This link is not viewable by the eye, but the assistive technology devices can read (or detect) it and access the text file."

Their PDFs are designed to use with; Adobe Accessibility Site which converts PDF files into ASCII and HTML.