Less dense substances move upwards to form a crust.

密度小的物质向上浮动并形成一层皮。

Most of these nourishing substances are in the yolk of the egg.

这些营养物质大部分在蛋黄里。

These are substances which specifically latch onto the protein on the cell membrane.

这些是专门黏附在细胞膜蛋白质上的物质。

Emotional upsets generate powerful and deadly toxic substances.

情绪的不安会产生强大而致命的有害物质。

Imagine what these poisonous substances can do to your own body.

想象一下这些有毒物质会对你的身体造成什么影响。

These substances leak from the rusty barrels and pollute the soil.

这些物质从生锈的桶中渗出，然后污染了土壤。

The process allows many poisonous substances to escape into the environment.

这个过程让许多有毒物质进入到了自然环境中。

All substances, whether they are gaseous, liquid or solid, are made of atoms.

一切物质，不论它们是气体、液体还是固体，都是由原子构成的。

They don't realize that familiar substances such as alcohol and tobacco are also drugs.

他们没有意识到像酒精和烟草这样熟悉的物质也是毒品。

They don't realize that familiar substances such as alcohol and tobacco are also drugs.

他们没有意识到像酒精和烟草这样熟悉的物质也是毒品。

In the unfertilized egg, the substances are inactive and are not distributed homogeneously.

在未受精卵中，这些物质是不活跃的，而且分布不均匀。

Some poisonous substances are flowing into the rivers that are sources of our drinking water.

一些有毒物质流入我们作为饮用水的河流中。

In experimenting we find out that sound travels with different velocities through different substances.

在实验中，我们发现声音以不同的速度通过不同的物质而传播。

These noxious substances limit caterpillars' growth and reduce the number of eggs that female moths lay.

这些有毒物质会限制毛毛虫的生长，减少雌蛾产卵的数量。

In study after study, there's a positive reaction in almost one-third of the patients taking harmless substances.

在一项又一项研究中，几乎有三分之一的病人在服用无害物质后产生了正反应。

The milk of many mammals contains cannabinoids, substances that are known to stimulate certain receptors in the brain.

许多哺乳动物的奶含有大麻素，这种物质可以刺激大脑中的某些受体。

Ok, venomous snakes are the ones that secrete poisonous substances or venom, like the snakes of the viper family or cobras.

毒蛇是一种分泌有毒物质或毒液的动物，像蝰蛇科的蛇或眼镜蛇。

Holland's system received a severe test when a truck loaded with chemical substances caught fire in the tunnel and exploded.

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。

When the egg is fertilized, the substances become active and, presumably, govern the behavior of the genes they interact with.

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。

According to Klawans and others, ritual impurity arises from physical substances and states which are not in themselves sinful.

据克洛文和其他人所说，仪式上的不洁产生于物质和状态，它们本身并不有罪。

Other links may involve changes in brain temperature and the release of neurotransmitters (substances that transmit nerve impulses.)

另一种联系可能会涉及到大脑温度的变化和神经递质（传递神经冲动的物质）的释放。

The toxic substances that fear, anger, frustration and stress produce not only kill guinea pigs but kill us off in a similar manner.

恐惧、愤怒、沮丧和压力产生的有毒物质不仅会杀死豚鼠，还会以类似的方式杀死我们。

The substances that make up both groups of planets are divided into three groups—gases, rocks, and ices—based on their melting points.

这两组行星的构成物质根据熔点分为三类：气体、岩石和冰。

Being frightened makes your brain flood with healthy chemical substances that excite your mood and release feelings of great excitement.

受惊吓时会让你的大脑充满一些健康的化学物质，能刺激你情绪，让你十分兴奋。

All substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect.

所有形式的物质，都可以根据它们吸收的光的波长以及反射的光的波长来区分。

The same minerals that occur in refractory inclusions are believed to be the earliest-formed substances to have condensed out of the solar nebula.

难熔的内含物中的那种矿物质，也被认为是最早形成的太阳星云凝结的物质。

As part of her job, she conducted field research on toxic substances in the environment, often in minority communities located near large industrial polluters.

作为工作的一部分，她对环境中的有毒物质进行了实地研究。这些物质通常来源于大型工业污染源附近的少数民族社区。

Evidence from a 1997 study at the University of California shows that several patients who received such substances were able to produce their own natural drug.

1997年加利福尼亚大学的一项研究表明，一些接受了这种物质的病人能够产生他们自己的天然药物。

Now, Laser Spectroscopy, which is the focus of your assignment, works by measuring very precisely what parts of the spectrum are absorbed by different substances.

现在来说说激光光谱学，这是你们作业的重点，激光光谱学可以非常精确地测量光谱的哪些部分被不同物质吸收。

She found many families were being exposed to high, sometimes deadly, levels of chemicals and other toxic substances, but she was not allowed to make her information public.

她发现，许多家庭都暴露在高水平的、有时是致命的化学物质和其他有毒物质中，但她不被允许公开自己的信息。