  This is the introductory part of my PhD thesis which consists of two parts,
the separate introduction and four published articles. The introduction begins
by a technically detailed description of the DGLAP evolution and the fast
numerical solving method for the DGLAP equations, which has been used in the
numerical works of the published articles of this thesis. A write-up of the
next-to-leading order (NLO) calculations for the deeply inelastic scattering
(DIS) and the Drell-Yan (DY) dilepton production cross-sections is also
included. The formalism of the inclusive single hadron production at NLO is
described as well, although less rigorously. The introductory part ends with a
discussion of the global QCD analyses in general, with a special attention paid
to the major work of this thesis, the NLO analysis of nuclear parton densities
and their uncertainties.
