用首次积分法，讨论了带奇异边界条件的非线性常微分方程解的存在性、不存在性和唯一性。

By the first integral method, the existence, uniqueness and nonexistence of solutions for some nonlinear ordinary differential equations with singular boundary condition are discussed.

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利用一个著名的不动点指标定理，获得了该方程周期正解的存在性、多重性和不存在性。

By using a well-known fixed point index theorem, we obtain the existence, multiplicity and nonexistence of positive periodic solution(s) to this equation.

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The opposition is between poetry that makes money and poetry that, precisely because it is good poetry as modern poetry defines it, does not.

对立性主要存在于为了赚钱的诗歌和,不为金钱的角度，现代诗歌意义上的,好诗歌之间的分歧。

耶鲁公开课 - 现代诗歌课程节选

These are long-term government bonds and I--now these are--since they're long-term, they have some uncertainty and variability to them.

这些是长期政府债券,由于它们是长期的，就存在不确定性和变化性。

耶鲁公开课 - 金融市场课程节选