By using a new three-solution theorem, we obtain the existence and multiplicity of positive solutions for fourth-order boundary value problem.

讨论了四阶边值问题，通过应用一个新的三解定理，得到了其解的存在性与多重性。

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By using a fixed point theorem of mixed monotone operators in cone, this paper studied a fourth-order nonlinear singular boundary value problem, namely a class of elastic beam equation.

利用锥上的混合单调算子不动点定理，本文研究了一类四阶奇异非线性微分方程的边值问题，即一类弹性梁方程问题。

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In this paper, the author discusses the existence of solutions to initial boundary value problem of nonlinear parabolic equations and obtains the existence theorem.

讨论了一类非线性抛物型方程的初边值问题解的存在性，并得出了解的存在性定理。

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