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Professor Keyak says the measurement is much greater than monthly reductions in bone mineral density of point four percent and one point eight percent.
VOA: special.2009.03.10
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We can graph out what this is where we're graphing the radial probability density as a function of the radius.
我们可以，画出它来,这是径向概率密度,作为半径的一个函数图。
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It's one of the only compounds, there's only I think three, where the density actually goes down when it freezes.
它是我见过的，唯一一个，在降温时密度下降的化合物。
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Another way to measure bone-density is called peripheral bone mineral density testing.
VOA: special.2010.08.31
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Sometimes we have a very electronegative atom that's going to take more of its equal share of electron density.
有时候我们会有一个电负性很高的原子,它将会获取更多的共用电子密度。
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Those are low density, so they are very permeable to oxygen.
VOA: special.2011.02.01
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You make the volume infinitely large, the density of the gas infinitely small.
密度无限小，气体分子之间的相互作用。
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This mixing is a product of the oceans' density and buoyancy.
VOA: special.2011.06.22
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We have instead what's called a probability density when we have continuous random variables.
所以我们用概率密度的概念来描述,连续型随机变量的情况
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We turned another corner around the central plaza area and the density of people is even greater over here.
VOA: standard.2010.01.14
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How is anyone going to give you a density of anything?
你怎样获得任意物体的密度
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It has a lot more energy density than batteries,".
VOA: standard.2009.09.02
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Okay, the higher caloric density.
没错,高热量密度
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They're prescribed to increase bone density and prevent fractures.
VOA: standard.2010.03.14
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We can talk about the wave function squared, the probability density, or we can talk about the radial probability distribution.
我们可以讨论它,波函数的平方，概率密度，或者可以考虑它的径向概率分布。
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And when we define that as r being equal to zero, essentially we're multiplying the probability density by zero.
当我们定义ｒ等于０处，事实上是把概率密度乘以０．
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So for example, that might have a formal charge of negative 1, because to some extent it has gained that much electron density that it now has a formal charge that's negative.
比如，可能它的形式电荷为负一，因为在一定程度上它得到了这么多的共用电子密度,那么它现在就有了负的形式电荷。
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Think of anything else with the density goes down when it freezes, and think about where we would be if that wasn't the case.
想想有没有其他的物质,在降温时密度会变大，再想想如果不是这种情况,我们将会怎么样。
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And then he says the tetrachloride will be volatile, 9 and it will have a density of 1.9.
他说四氯化物具有不稳定性，密度是1。
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And he predicts the density of the oxide of the yet undiscovered element.
他预测这个还未被发现的元素的,氧化物的密度。
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Ah, but density is mass over volume.
但密度是质量除以体积
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So, one way we could look at it is by looking at this density dot diagram, where the density of the dots correlates to the probability density.
其中一个理解它的方法,就是通过看这个密度点图，这里点的密度,和概率密度想关联的。
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So you can think about how these 2 things combined are going to be electronegativity, which is a measure of how much an atom wants to pull electron density away from another atom.
因此你可以想象出,这两样性质合起来就是电负性，也就是一个度量，关于一个原子,有多希望把另一个原子的电子密度拉过来的。
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So again if we look at this in terms of its physical interpretation or probability density, what we need to do is square the wave function.
如果我们从物理意义或者,概率密度的角度来看这个问题，我们需要把波函数平方。
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But a real key in looking at these plots is where we, in fact, did go through zero and have this zero probability density.
是我们经历这些零值,而且有这些零概率密度,我们把它叫做节点。
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So it's just a measure of how much does one given atom want to pull away electron density from, let's say, an adjacent atom.
因此，它就是度量一个给定原子有多么,想把电子密度拉过来，可以说，从相邻的一个原子那里。
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So if I try to rotate my 2 atoms, you see that I have to break that pi bond, because they need to be lined up so that the electron density can overlap.
如果我要试着转动两个原子，你会看到我必须要打破一个π键，因为他们需要连接起来,让那些电子能够重叠。
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This is not a node because a node is where we actually have no probability density.
因为节点处是,没有概率密度的,所以。
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So again, we can think about the probability density in terms of squaring the wave function.
同样的，我们可以把,波函数平方考虑概率密度。
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So, what we're going to define is just let's just capture 90% of that electron density.
所以，我们所定义的,只包括百分之九十的电子密度。
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