[1] Nieto J J. Nonlinear second-order periodic boundary value problems. J Math Anal Appl, 1988, 130: 22--29
[2] Gossez J P, Pmari P. Periodic solutions of a second order ordinary differential equation: a necessary and sufficient condition
for nonresonance. J Differential Equations, 1991, 94: 67--82
[3] RachunkovàI, Tvrd\'y M, Vrkoc I. Existence of nonnegative and nonpositive solutions for second order periodic boundary value
problems. J Differential Equations, 2001, 176: 445--469
[4] Erbe L H, Mathsen R M. Positive solutions for singular nonlinear boundary value problems. Nonlinear Anal TMA, 2001, 46: 979--986
[5] Jiang D, Chu J, O'Regan D, Agarwal R P. Multiple positive solutions to superlinear periodic boundary value problems with repulsive singular forces. J Math Anal Appl, 2003, 286: 563--576
[6] Torres P J. Existence of one-signed periodic solutions of some second-order differential equations via a Krasnoselskii fixed point
theorem. J Differential Equations, 2003, 190: 643--662
[7] O'Regan D, Wang H. Positive periodic solutions of systems of second-order ordinary differential equations. Positivity, 2006, 10: 285--298
[8] Lin X. Multiplicity of positive periodic solutions to second-order singular differential systems. Acta Mathematica Scientia, 2006, 26A: 1105--1114
[9] Precup. A vector version of Krasnoselskii's fixed point theorem in cones and positive periodic solutions of nonlinear systems. J Fixed Point Theory Appl, 2007, 2: 141--151
[10] Yao Q. Positive solutions of nonlinear second-order periodic boundary value problems. Appl Math Letters, 2007, 20: 583--590
[11] 姚庆六. 一类奇异二阶边值问题的正周期解. 数学学报(中文版), 2007, 50: 1357--1364
[12] Wang H. Periodic solutions to nonautonomous second-order systems. Nonlinear Anal TMA, 2009, 71: 1271--1275
[13] Yao Q. Periodic positive solutions to a class of singular second-order ordinary differential equations. Acta Applicanda Mathematicae, 2010, 110: 871--883
[14] 姚庆六. 一类奇异二阶两点边值问题多重正解的局部存在性定理. 数学年刊(中文版), 2007, 28A: 581--588
[15] Yao Q. Existence and multiplicity of positive solutions to a singular elastic beam equation rigidly fixed at both ends. Nonlinear
Anal TMA, 2008, 69: 2683--2694
[16] Yao Q. Local existence of multiple positive solutions to a singular cantilever beam equation. J Math Anal Appl, 2010, 363: 138--154 |