[en] Fission product cumulative and independent yields were determined for 238-U(n,f) and 232-Th(n,f) reactions with essentially monoenergetic neutrons of 3 and 14 Mev. Fission product activities were measured by Ge(Li)γ-ray spectrometry of irradiated 238-U and 232-Th foils. These experiments allowed us to measure a great number of cumulative yields and to obtain the fission product mass distributions corresponding to the studied reactions mentioned above. The mass distributions were completely interpreted by nucleon shell effects and proton even-odd effects. The independent yield measurements are sometimes not possible using the activation technique because of the fission fragment decay data. The values which can not be measured were determined using the measured mass yields and a prediction systematic of fractional independent yield. The results allowed us to obtain the nuclear charge distributions and to estimate proton even-odd effect corresponding values. This effect decreases when the excitation energy of the fissioning nucleus increases, this shows the importance of this parameter in the viscosity study of the nuclear matter. In conclusion, the shell effects observed in the mass distributions show that the static aspect of the fission mechanism plays a great role during the fission process, and observed proton even-odd effects act for a weak nuclear viscosity. 54 refs., 27 figs., 25 tabs