The existence of solutions for second order periodic boundary value problems in general Banach spaces is discussed.The theory of noncompactness measure and Sadovskii fixed point theorem of condensing map are applied to these problems,and some existence and uniqueness results are obtained.%研究了一般Banach空间中二阶周期边值问题解的存在性．利用非紧性测度的性质与凝聚映射的Sadovskii不动点定理，获得了若干解的存在性与唯一性结果．
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