来自《耶鲁大学开放课程：新生有机化学 第6集 第6集》

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  This was done by Leiserowitz and Ziva Berkovitch-Yellin
  这是雷兹诺维兹和伊娃·博科维奇·耶林
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  thirty-three years ago.
  33年前完成的工作
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  So this is an interesting molecule
  这是个很有趣的分子
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  because it has lots of different kinds of bonds in it
  因为其中包含各种化学键
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  single bonds,
  有单键
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  double bonds--in fact three double bonds in a row
  双键 而且是三个连续的双键
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  and also benzene rings that have these resonance bonds.
  还有苯环 其中包含共振键
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  Okay, so we're going to look first at one of the benzene rings.
  我们首先来看看这些苯环
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  So this map that I'm showing you here is a difference density map.
  这里显示出的 就是差分电子密度图
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  It's the total, minus what it would be for the atoms.
  是实验结果与理论模型之差
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  But notice what was subtracted is just the carbon density;
  这里做减法时 只考虑了碳原子
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  didn't subtract hydrogens.
  没有考虑氢原子