Simple quantum-chromodynamic parametrizations of parton distributions beyond the leading order of asymptotic freedom

It is shown that the $Q^2$ dependence of the nonsinglet (NS) parton distributions in quantum chromodynamics with leading- and next-to-leading-order corrections included can be adequately represented by simple analytic expressions, similar to those proposed by Gaemers and one of the authors. The pattern of higher-order corrections to the $Q^2$ dependence of $F_2^{\mathrm{NS}}(x,Q^2)$ and of $F_3(x,Q^2)$ is discussed.