But in sigma orbitals, you have no nodal planes along the bond axis, so if we had a nodal plane here, we'd see an area where the wave function was equal to zero.

但在sigma轨道里，沿着轴向是没有节点平面的，如果我们有个节点，我们就会看到某个地方波函数等于0。

麻省理工公开课 - 化学原理课程节选

So what I'd like to do now is focus on a piece that emphasizes--foregrounds-- just the first axis, pitch.

那么现在我要做的是集中精力于一首乐曲,它所强调的,突出的,只是这第一维,音高

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So you can see, if it's spinning on its own axis in this direction we'd call it spin up, where as this way it would be what we call spin down.

你们可以看到，如果它绕自己的轴朝这个方向转,我们就说它是自旋朝上，这个方向我们叫它自旋朝下。

麻省理工公开课 - 化学原理课程节选