For example (just as rough proof of concept)
Research articles: Pretty much any academic library website for published stuff, arxiv.org for white papers in computer science and math, pubmed for biosciences
audio equipment: gearspace.com
Encyclopedia: Wikipedia
Thesaurus: Wordhippo.com
The idea is to avoid needing to visit a search engine. Might be a high idea.
awesome-lists might be what you’re looking for. If you’re talking platforms, search ddg or alternativeto.net for “social bookmarking” I believe there’s even some self hostable options that may have the functionality you want. Sorry for the “look it up” suggestion, I don’t know your specific needs or remember exact names offhand.