Currently not, the modifiers for tech group are all the same. However, you could change this in common\technology.txt, which would change the rate at which you research (the numbers are as percentages, ie 1.0 = 100%, 0.8 would be 80% and so on). You could therefore slow down a group's technological advance by half by making it 0.5, etc.
It also means you have the ability to target all countries in a tech group with events.