本文研究了一类三次系统无穷远点的中心条件与赤道极限环分枝问题。

Studied in this paper are center conditions and bifurcation of limit cycles from the equator for a class of cubic polynomial system.

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不过问题是它们没法自然繁殖，于是有心人就截取了部分枝条嫁接到其他橙树上，希望生产出更多美味水果。

Since the new tree was unable to reproduce naturally, caretakers amputated some of its limbs and grafted them onto other citrus trees to produce more of the desirable fruit.

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本文首先分析了传统定性推理方法中存在的歧义性分枝和建模手段不强的问题。

In this paper, the problem of ambiguous branches and the weakness of modeling measures existed in the classical qualitative reasoning are analyzed at first.

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