目的研究一类二次微分系统的极限环存在性及唯一性。

Aim To discusses the existence and uniqueness of limit cycles for a class of quadratic system.

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用二次微分简易示波伏安法测定了金刚石酸洗废液中的痕量镍。

Trace nickel in waste solution from process of diamond cleaning by acid is determined by second order differential simple oscillographic voltammetry.

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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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So here I've written for the hydrogen atom that deceptively simple form of the Schrodinger equation, where we don't actually write out the Hamiltonian operator, but you remember that's a series of second derivatives, so we have a differential equation that were actually dealing with.

这里我写出了,氢原子薛定谔方程的,最简单形式，这里我们实际上,没有写出哈密顿算符,但是请记住那你有，一系列的二次导数,所有我们实际上会处理一个微分方程。

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