What do the stats in S.T.A.L.K.E.R.: Shadow of Chernobyl mean?

In the game, there are tons of artifacts that have effects on certain attributes to your character. These include "Bulletproof Cap", "Impact", "Chemical Burn", "Rupture", and I think four more. However, in the game, there is no explanation as to what these statistics mean. And spending half an hour searching for an answer didn't help either. Can anybody explain to me what each of these attributes means?