Anisotropy of $H_{c2\mathrm{}}$ and the breadth of the resistive transition of polycrystalline $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ in a magnetic field

Measurements of the resistive transition in a magnetic field of a polycrystalline sample of the high-$T_c$ superconducting oxide $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ were used, together with a theoretical analysis based on the anisotropic Ginzburg-Landau theory of the upper critical field $H_{c2\mathrm{}}$ and the Davidson-Tinkham equation for the resistivity of a heterogeneous aggregate of superconducting and normal crystallites, to obtain values of $H_{c2\mathrm{}}$, in the temperature range 83-93 K, for fields parallel and perpendicular to the copper-oxygen layers. The anisotropy ratio for $H_{c2\mathrm{}}$ is found to be in the range of 25-50.