The research screen can have issues with all the research topics getting hidden.  Basically, at the start of the game, Choose Warfare, then click and drag Civ on top of the slot.  Warfare will usually return to the top of the screen.  Click and drag warfare back down again.  Civ may pop back to the top.  Repeat once or twice and when you try to drag warfare down again and it will (usually) disappear.  Civ will still be in the slot but, warfare is missing.  Double-click on the research slot and both will reappear at the top but, doing this shuffle will cause them to vanish again.

Later in the game, when more techs are available, the problem can be repeated with other techs, especially when using the warfare tech.  When/if you get the warfare tech to vanish, the rest can then be folded into the bottom.  Again, doubleclicking the slot will return all the techs to the top.