然而，当火山物质在喷发过程中积累并随后崩塌时，它的高度经常发生变化。
However, its height often changes when volcanic material accumulates during eruptions and subsequently collapses.
当大陆板块停留在一个热点上时，从深层升起的物质就会形成一个广阔的圆顶。
When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome.
当一辆装满化学物质的卡车在隧道中起火并爆炸时，霍兰德的系统受到了严峻的考验。
Holland's system received a severe test when a truck loaded with chemical substances caught fire in the tunnel and exploded.
有一个便于取用的闪电“转换器”，材料科学家们就可以弄清当强大的电流与物质相遇时会发生什么。
With a lightning "switch" at their fingertips, materials scientists could find out what happens when mighty currents meet matter.
当一个大型天体撞击行星或月球时，物质会被抛射出去，从而在行星上形成一个洞，造成局部质量不足的现象。
When a large body strikes a planet or moon, material is ejected, thereby creating a hole in the planet and a local deficit of mass.
当岩浆撞击岩层时，会出现岩屑，形成液态和固态物质的混合物。
As the magma smashes through layers of rock, it rips out debris, creating a mix of liquid and solid material.
最近的一项研究似乎指出了一个事实，当物质和反物质最初被创造出来的时候，有更多的物质粒子，这使得我们生活的宇宙得以形成。
A recent study seems to point to the fact that when matter and anti-matter were first created, there were slightly more particles of matter, which allowed the universe we all live in to form.
潜热在物质形态变化时被吸收或释放，例如当物质从液体变为气体或从气体变为液体时这一过程就会发生。
Latent heat is absorbed or released whenever matter changes phase, as when matter changes from liquid to gas, for example, or from gas to liquid.
当卵子受精时，这些物质变得活跃起来，并可能控制与它们相互作用的基因的行为。
When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with.
尽管科学理论的大致框架能被直观地勾勒出来，但当物质世界的一部分最终被理解时，它的描述看起来通常就像数学课本中的一页内容。
Though the broad outline of a scientific theory can be sketched intuitively, when a part of the physical universe is finally understood, its description often looks like a page in a mathematics text.
当营养物质在环境中被反复使用时，我们称之为营养循环。
When nutrients are used over and over in the environment, we call that a nutrient cycle.
当另一种植物获得化学物质时，它就会开始释放自己不同的化学物质。
When another plant gets the chemicals, it starts to give out its own, different chemicals.
当它们发现干旱期延长时，它们会改变自己的新陈代谢，在它们的组织中产生糖和某些与应激相关的蛋白质和其他物质。
When they detect an extended dry period, they divert their metabolisms, producing sugars and certain stress-associated proteins and other materials in their tissues.
当笛卡尔尝试着求助于非物质概念，来为思维留出空间的时候，霍布斯却将其否认。
And so when Descartes tries to appeal to the idea of immaterial substances making room for mind, Hobbes just denies it.
当黑洞吞噬附近的行星时，一些落入其中的物质以热等离子的形式逃出生天。
As the black hole devours nearby stars, some in-falling matter escapes as hot plasma.
当永冻层融化，其中的有机物质分解就会释放甲烷。
Methane is released when organic material in the thawing permafrost decomposes, which gradually releases methane.
当火球冷却时，内部的气化物质压缩形成固态微粒云。
As the fireball cools, the vaporized materials in it condense to form a cloud of solid particles.
当物质落入黑洞时，会被加热到上百万度，并喷发出X射线。
As material falls in to a black hole, it heats up to millions of degrees and spews X-rays.
这是真的，当物质和反物质相遇时，它们会在大爆炸相互湮灭，然后把它们的质量转换为能量。
It's true that when matter and antimatter meet, they do annihilate in a big explosion and convert their mass to energy.
但是现在，想看看，当物质不是合适的比例的话会发生什么。
But now, I want to look at what happens when things are not in proper proportion.
当一小块反物质击打天文台并与“正常”的物质相碰撞时，两个粒子都立即湮灭，并转变为伽马射线-费米就可以检测到它。
When a piece of antimatter strikes the observatory and collides with "normal" matter, both particles immediately annihilate and are transformed into gamma rays - which Fermi can detect.
当水被搅动时，就会将这些化学物质释放到空气中然后被人体吸入。
As the water is agitated, these chemicals are released into the air and then breathed in.
当人们设定目标时会有很多动机——同僚压力，犯罪，贪恋，物质主义，复仇，骄傲，羡慕，或者嫉妒。
People can be motivated by many things when they set goals -- peer pressure; guilt, greed, materialism, revenge, pride, envy, or jealousy.
当形成的物质达到几个碳原子层的厚度时，便形成了被称为石墨吩的透明物质。
When the substance is only a few of these layers thick, though, it is known as graphene and is transparent.
但当涉及到矿物质，白面包获胜。
体重增加:当一个人很早去睡觉，会产生特别的化学物质去抑制减肥。
Weight Gain: When one goes to sleep early, one produces specific chemicals that inhibit weight loss.
当这种物质进入到人体，所发生的反应就会受这种合成分子的控制。
When the substance enters the human body, it forces a reaction which the hybrid molecule itself controls.
当撞击发生时，星团中的暗物质也发生碰撞。
When the impact happened, the dark matter in the clusters also collided.
当一个粒子遇到它的反物质的时候，他们会湮灭彼此，同时放出夺目的高能闪光。
When a particle encounters its antiparticle, they "annihilate" each other, disappearing in a high-energy flash of light.
当一个粒子遇到它的反物质的时候，他们会湮灭彼此，同时放出夺目的高能闪光。
When a particle encounters its antiparticle, they "annihilate" each other, disappearing in a high-energy flash of light.
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