(if I could only figure out the fucking tech tree!)
There's a button that shows it, otherwise most of the resource ones are just like a linear find raw resource -> process raw resource (-> process refined resource)
path, although the nuclear one is longer and weirder because you have to research the concept of radioactive stuff, then survey for uranium, then learn how to oxidize uranium, then learn how to enrich that, and then learn how to make fuel rods from that, and only then can you research how to make nuclear power plants although honestly just selling the fuel rods is probably better because they're absurdly valuable on their own to the point that I think they may actually be more valuable than the power they can generate.