  We present the complete next-to-leading order (NLO) QCD corrections to $tZ$
associated production induced by the model-independent $tqg$ and $tqZ$
flavor-changing neutral-current couplings at hadron colliders, respectively.
Our results show that, for the $tuZ$ coupling the NLO QCD corrections can
enhance the total cross sections by about 60% and 42%, and for the $tcZ$
coupling by about 51% and 43% at the Tevatron and LHC, respectively. The NLO
corrections, for the $tug$ couplings, can enhance the total cross sections by
about 27%, and by about 42% for the $tcg$ coupling at the LHC. We also consider
the mixing effects between the $tqg$ and $tqZ$ couplings for this process,
which can either be large or small depending on the values of the anomalous
couplings. Besides, the NLO corrections reduce the dependence of the total
cross sections on the renormalization or factorization scale significantly,
which lead to increased confidence on the theoretical predictions. And we also
evaluate the NLO corrections to several important kinematic distributions.
