chemical是什么意思？

A drug is a chemical substance.

The supervisor of the laboratory is beginning to get headaches and dizzy spells because she says it's dangerous to breathe some of the chemical smoke there.

Muscle performance can also be affected by a phenomenon called "central fatigue", in which an imbalance in the body's chemical messengers prevents the central nervous system from directing muscle movements effectively.

It will drive producers of chemical fertilizers out of business.

In cases where sewage mud is used, expensive chemical fertilizer use can be avoided.

Way up north in the Canadian Arctic, seabirds are picking up dangerous chemicals in the ocean and delivering them to ponds near where the birds live.

The bodies of fish and other meat eaters can build up high levels of the chemicals.

Salmon also carry dangerous chemicals as the fish migrate between rivers and the sea.

People who live, hunt or fish near bird coloniesneed to be careful, the researchers say, The birds don’t mean to cause harm, but the chemicals they carry can cause major problems.

We can tear apart the great grass cover of the western plains and pour toxic chemicals into the soil until the soil is dead and blows away in the wind.

Chemical testing showed that over the two years before her death, she moved about every two months.

Heating this chemical compound drives off carbon dioxide gas, leaving calcium oxide.

The chemical composition of rainfall changes slightly as rain clouds move.

The method relies on measuring how chemical variations in drinking water show up in people's hair.