CONDUCTIVIDAD TERMICA ELECTRON SPIN RESONANCE RESONANCIA DE SPIN ELECTRONICA SUPERCONDUCTORES Thermal conductivity ANISOTROPY Angular dependence of g-shifts of Kramer's doublets in a crystal under uniaxial stress Angular variation of the BPR llnewidth of Ni2+ in Ca0 COUPLING CONSTANTS COVALENCE COVALENCIA CRISTALES IONICOS DISLOCACIONES DE FRANK DISLOCATIONS ELASTICIDAD EPR and ENDOR of BaF2,: Tm3+ under uniaxial stress ESPECTROS ESPECTROSCOPIA ESTRUCTURA HIPERFINA Efectos de tensiones internas cristalinas en espectros de resonancias paramagnética electrónica caso Ni Z+ en OCa Evidence of low-energy tunneling excitations in the high-Tc superconductor YBa2Cu3O7-x FLUJO MAGNETICO Física HAMILTONIANS HYPERFINE STRUCTURE IMANTACION IMPUREZAS IMPURITIES INTERSTICIALES INTERSTITIALS