摘要：
A new necessary and sufficient condition for the existence of eventually positive solutions was obtained for a class of odd-order neutral differential equations. Some lemmas were also introduced that were useful in the proof of main results. The obtained results indicate that neutral differential equation has no eventually positive solution.
关键词：
positive and negative coefficients;neutral differential equation;oscillation;eventually positive solution
摘要：
New sufficient conditions for the oscillation are obtained for all solutions of a class of first order neutral differential equations with positive and negative coefficients.
摘要：
Oscillation properties of the solutions of a class of odd order neutral delay parabolic differential equations were investigated via the method of differential inequalities. Necessary and sufficient conditions for oscillation of odd order neutral delay parabolic differential equations were studied. Numerical method were used for the investigation .
