Sometimes you see this written when you see p orbitals, one is written as plus, one is written in minus.

有时候你们看ｐ轨道时会看到，一个写成正号一个写成负号。

麻省理工公开课 - 化学原理课程节选

So we have 4 plus 5, but we're actually not done yet, because it's c n minus, so if we have minus, we actually have an extra electron in our molecule.

我们有四个加上五个，但是我们实际上还没做完，因为这是个负离子，所以如果我们有这个负号，那么我们的分子实际上还有一个额外的电子。

麻省理工公开课 - 化学原理课程节选

So we know that in each case the heat is going to be the opposite of the work, but the work isn't the same in these two different ways of getting from here to here, right. So let's just see it explicitly. Here's our qA.

所以我们知道在每种情形下功,与热量相差一个负号,但从这里到这里，在这两条路径,中的功是不同的，对吧？,那么让我们明确地看一下。

麻省理工公开课 - 热力学与动力学课程节选

This has a minus and that doesn't have a minus.

这里有一个负号而那里没有

耶鲁公开课 - 基础物理课程节选

Another way to say that it's going to be less, so you don't get confused with that the fact this is in the numerator here, there is that negative sign so it's less energy but it's a bigger negative number that gives us that less energy there.

另一个方式去说它将会变得很低实用，你们不用在这里的计算器的事实感到迷惑,这里有一个负号实用，它是更少的能量,但它是一个更大的数字,这里了它给了我们更少的能量。

麻省理工公开课 - 化学原理课程节选

We have the minus because we're adding a negative charge from the electron.

有这个负号的原因是,我们得到一个电子后增加了一个单位负电荷。

麻省理工公开课 - 化学原理课程节选

So if delta v is negative, in this case delta v is negative, OK, delta v is negative, pressure is a positive number, negative times negative is positive, work is greater than zero.

也就是当活塞,压缩气体的时候，做的功是正的，按照这一规定,我们需要在这里，加上一个负号，这是习惯规定。

麻省理工公开课 - 热力学与动力学课程节选