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摘要
Let Omega subset of R(N) be a smooth bounded domain and let f (sic) 0 be a possibly discontinuous and unbounded function. We give a necessary and sufficient condition on f for the existence of positive solutions for all lambda > 0 of Dirichlet periodic parabolic problems of the form Lu = h(x, t, u) + lambda f(x, t), where h is a nonnegative Caratheodory function that is sublinear at infinity. When this condition is not fulfilled, under some additional assumptions on h we characterize the set of As for which the aforementioned problem possesses some positive solution. All results remain true for the corresponding elliptic problems.
- 出版日期2011-12
