The decrease in @R05156@ brought about by the addition of a substance @I03035@), by virtue of its effect on the concentration of a reactant, @C00876@ or @R05171@. For example, molecular oxygen and p-benzoquinone can react as 'inhibitors' in many reactions involving @R05066@ as intermediates by virtue of their ability to act as @S05495@ toward these radicals. If the rate of a reaction in the absence of @I03035@ is \(v_{0}\) and that in the presence of a certain amount of @I03035@ is \(v\), the degree of inhibition (\(i\)) is given by: \[i=\frac{v_{0}- v}{v_{0}}\]