Polarization phenomena in the reaction NN to NNpi near threshold

First calculations for spin-dependent observables of the reactions $pp \to pp\pi^0$,$pp \to pn\pi^+$and$pp \to d\pi^+$ near threshold are presented, employing the J"ulich model for pion production. The influence of resonant (via the excitation of the $\mathrm{\Delta }(1232)$) and non-resonant p-wave pion production mechanisms on these observables is examined. For the reactions $pp \to pn\pi^+$and$pp \to d\pi^+$ nice agreement of our predictions with the presently available data on spin correlation coefficents is observed whereas for $pp\to pp{\pi }^0$ the description of the data is less satisfying.