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The study is said to be the first to examine in detail measurements of bone strength instead of bone density.
VOA: special.2009.03.10
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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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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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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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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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This mixing is a product of the oceans' density and buoyancy.
VOA: special.2011.06.22
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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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The calorie density has changed because food is processed, so the calories in the fat and the sugar that can get squeezed into things made possible by technological changes has shifted things a lot.
食品经过加工,热量密度发生了变化,添加到食品中的脂肪和糖类,其卡路里含量可通过技术手段进行调整,进而造成很大不同
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So, what you see is near the nucleus, the density is the strongest, the dots are closest together.
你看在核子附近，密度非常高，这些点非常密。
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Because we know as we go to infinity, even though the density gets smaller and smaller and smaller, we still have electron density very far away from the nucleus.
因为我们知道即使到了无穷远处，尽管电子密度会变得非常非常非常小，但我们仍然有一定的电子密度，无论离原子核多远。
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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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So, again we can use these probability density plots, which are just a plot of psi squared, where the density of the dots is proportional to the density, the probability density, at that point.
同样的我们可以利用这些概率密度图，这是psi的平方的图，这里面点的密度，正比于概率密度。
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So we can think of a third case where we have the 3 s orbital, and in the 3 s orbital 0 we see something similar, we start high, we go through zero, where there will now be zero probability density, as we can see in the density plot graph.
第三个例子那就是,3s轨道,在3s轨道里，我们看到类似的现象,开始非常高，然后穿过，这里，概率密度是0，就像你们在概率密度图里看到一样，然后我们到负的。
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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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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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So, doing those probability density dot graphs, we can get an idea of the shape of those orbitals, we know that they're spherically symmetrical.
概率密度点图上,我们可以对这些轨道的形状，有个大概了解,我们知道它们是球，对称的,我们今天不讲。
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But we can also think when we're talking about wave function squared, what we're really talking about is the probability density, right, the probability in some volume.
波函数平方,的时候，我们说的，是概率密度，对吧,是在某些体积内的概率，但我们有办法。
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So you can see that this is non-bonding, this is even worse than non-bonding, it's anti-bonding, because we're actually getting rid of electron density between the two nuclei.
所以你可以看到这是不成键的，它甚至比不成键还糟糕，它是反键，因为我们实际上是去掉了,两个原子核之间的电子。
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So we can see if we look at the probability density plot, we can see there's a place where the probability density of is actually going to be zero.
就能看到,有些地方，找到一个电子的,概率密度,我们可以考虑。
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And when we take the wave function and square it, that's going to be equal to the probability density of finding an electron at some point in your atom.
当我们把波函数平方时，就等于在某处,找到一个电子的概率密度。
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So again, this is an anti-bonding orbital, and what you see is that there is now less electron density between the two nuclei than there was when you had non-bonding.
同样的，这是反键轨道，你们看到当你有反键轨道的时候,两个原子核中间的电子密度更小了。
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The reason that there is increased electron density here is you can see that these two orbitals come together and constructively interfere.
你们可以看到两个轨道,靠在一起相长叠加,这就是为什么中间的电子态密度增加了。
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So, instead of having the periodic variation of water, or the periodic variation of air density here we're talking about an electric field.
不像水或者空气密度的,周期变化，我们这里,讨论的是电场。
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At first it might be counter-intuitive because we know the probability density at the nucleus is the greatest.
起初我们觉得这和直观感觉很不相符,因为我们知道在原子核,出的概率密度是最高的。
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And we know that it's electron density between the nuclei that holds two atoms together in a bond.
我们知道是两个原子核之间的,电子密度保持两个原子在一起成键的。
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When we were talking about constructive interference, we had more electron density in between the 2 nuclei.
当我们讨论相长干涉的时候，在两个原子核之间有更多的电子密度。
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And so, the radial probability density at the nucleus is going to be zero, even though we know the probability density at the nucleus is very high, that's actually where is the highest.
所以径向概率密度,在核子处等于零，虽然我们知道在，核子处概率密度很大,实际上在这里是最大的，这是因为。
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So what we should expect to see is one radial node, and that is what we see here 3s in the probability density plot.
个节点,这就是我们，在这概率密度图上所看到的,如果我们考虑。
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Anywhere where that's the case we're going to have no probability density of finding an electron.
这时面内任何地方,找到电子的概率密度都是零。
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So, it's the x-y plane, you can see there's no electron density anywhere there.
它在ｘｙ平面，你们可以看到在这里没有电子密度。
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