The chemicals are hard to detect in low concentrations.

这些化学品在低浓度时很难被检测出来。

So grass leaves have protein at much lower concentrations.

所以小草叶片上的蛋白质含量要更低一些。

Freshwater fishes live in water with very low salt concentrations.

淡水鱼生活在含盐量很低的水中。

Tritium is present there in a very, very low concentration.

氚的浓度非常非常低。

There are hormones in milk, but only in very low concentrations.

牛奶中含有激素，但浓度非常低。

This allows jellyfish to thrive in waters that have extremely low oxygen concentrations.

这使得水母能够在极低氧浓度的水域中茁壮成长。

And molecules also diffuse from areas of high concentration to areas of low concentration.

分子也会从高浓度区域扩散到低浓度区域。

Luteinized theca cells respond to the low LH concentrations after ovulation by producing more progesterone.

LH水平降低会使黄素化的内膜细胞生成更多黄体酮。

They maintain a lower concentration of salt in their body fluids than the water around them.

它们的体液中盐的浓度比周围的水低。

The substance needs to move up the concentration gradient from a low concentration to a high concentration.

物质需要沿着浓度梯度从低浓度上升到高浓度。

So now our body is removing sodium from blood that already has a lower concentration of sodium.

所以这时我们的身体正在从钠离子浓度已经较低的血中排钠。

It is why people with lower oxygen concentration sometimes remove protective clothes atop Mount Everest; some freeze to death.

这就是为什么缺氧的人有时会在珠穆朗玛峰顶上脱下防护服；其中一些人甚至会因此冻死。

Or, in official terms, from the side with a lower concentration of solutes to one with a higher concentration.

或者，用更正式一点的话说，从溶质浓度较低的一侧到浓度较高的一侧。

Active transport moves molecules from a low concentration to a high concentration against the concentration gradient.

主动运输将分子逆着浓度梯度从低浓度移动到高浓度。

They were things that could easily move from a high concentration to a low concentration, that makes sense.

它们很容易从高浓度转移到低浓度，这说得通。

The substance binds to the protein carrier on the low concentration side and using energy from respiration.

这种物质结合在低浓度的蛋白质载体上，利用呼吸产生的能量。

This is because dogs expose us to certain germs and bacteria which help bolster our immune system in low concentrations.

这是因为狗会让我们接触某些细菌，处于低浓度的细菌环境有助于增强我们的免疫系统。

Just remember that for diffusion, the substance moves down the concentration gradient from a high concentration to a low concentration.

记住，对于扩散，物质沿着浓度梯度从高浓度向低浓度移动。

And that's because humans can taste it in solutions at really, really low concentrations, just a few parts per million.

那是因为人类可以在浓度非常非常低的溶解剂中尝到这种物质，仅百万分之一。

Water can travel across cell membranes from where there's a higher concentration of water to where there's a lower concentration.

水可以透过细胞膜从低渗透压一侧流至高渗透压侧。