  At large N_c the nucleon can be viewed as a soliton of the effective chiral
lagrangian. This picture of nucleons allows a consistent nonperturbative
calculation of the leading-twist parton distributions at a low normalization
point. We derive general formulae for the polarized and unpolarized
distributions (singlet and non-singlet) in the chiral quark-soliton model. The
consistency of our approach is demonstrated by checking the baryon number,
isospin and total momentum sum rules, as well as the Bjorken sum rule. We
present numerical estimates of the quark and antiquark distributions and find
reasonable agreement with parametrizations of the data at a low normalization
point. In particular, we obtain a sizeable fraction of antiquarks, in agreement
with the phenomenological analysis.
