The elastic properties of nematic compounds with terminal cyanoaromatic and containing cycles alyphatic groups were investigated. The terminal group structure has essential influence on the bend K-3 and splay K-1 elastic constants and their temperature dependences. The ninth and tenth members of 4-cyanophenyl 4’-n-alkyloxybenzoate series (nCPh) and cyanobiphenyl ether with ethylene-butylcyclohexane terminal group show pretransitional divergence of K-3 in the vicinity of the nematic-smectic phase transition Outside pretransitional temperature region the alternatation from odd to even n in nCPh series is accompanied by positive jumps of the ratio K-3/K-1 and change of the character of its temperature dependence. A striking unmonotonous temperature dependence of the elastic splay constant K-1 was founded for cyanobiphenyl ether with butylcyclohexane terminal group. The occurrence of frozen striped texture in a smectic phase after the nematic-smectic transition in the presence of magnetic field was found for all nematics with the temperature divergence of K-3. Distance between stripes was the less, the more magnetic induction.