Option at start - no one can trade research they have not researched themselves.



Sometime I want to give a helping hand to someone who is losing a war against my rival, so I give them quite a few techs for free. The very next turn, they trade the techs I gave them to my rival for peace.



I'm not sure whether it's more realistic or not, but IMO it makes for a better game if you can shore up a failing empire without the risk that everything will go to the empire you are a rival with.



Perhaps there could be a diplomatic no-trade option for accepting tech that was breakable, with significant penalties.



It doesn't make sense to me the way it is implemented now, really... trade 1 empire for an important tech, then sell it all around the galaxy.