来自《耶鲁大学开放课程：新生有机化学 第7集 第7集》

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  is a curvature of a function. Right?
  是一个函数的曲率 对吗
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  What's the first derivative?
  那么什么是一阶导数呢
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  Slope.
  斜率
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  Slope,
  是斜率
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  and the second derivative is how curved it is.
  二阶导数它的弯度
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  It can be curving down, that's negative curvature;
  它可能是向下弯 就是一个负的曲率
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  or curving up, that's positive curvature.
  向上弯 就是一个正曲率
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  So it can be positive or negative;
  所以它可正可负
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  it can be zero if the line is straight.
  如果是直线的话 也可以就是零
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  Okay. So note that the kinetic energy involves the shape of Ψ,
  因此注意动能包括Ψ的形状
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  how curved it is, not just what the value of Ψ is;
  它如何弯曲 不只是Ψ的值为多少
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  although it involves that too.
  虽然它也包括在内