When you go the research screen you often have lots of grayed out researches, at least if you shoot down a ufo early on. The only thing that is said is that you lack the materials or research necessary. My suggestion is that it would be stated exactly what is missing. "To research this you need item X and research Y" or something. If I'm being stupid and missing something obvious that is already there, I apologize, but I have looked both here, in game and in the wiki without finding anything.
