As far as I know there isn’t a completely automated way to approach this with a single node in KNIME. There have been a couple of recent threads around this topic on the forum:
The complicating factor when you look at something like Google Scholar is that the search results point to all sorts of different landing pages, and available formats change depending on the document (HTML, PDF, DOC, etc).
Now, if you already have a bunch of documents downloaded in a folder, this is much more straightforward since you can just use the Tika Parser to ingest the files.