本文给出在中国分类之下二次微分系统有中心时两种情况的通积分。

We give general integral of quadratic differential system with center in two cases under the Chinese classification.

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本文研究一个非线性双曲微分积分系统，它由H。

Here we study a nonlinear hyperbolic integrodifferential system which was proposed by h.

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