But only a small number of substances can be said to have fundamentally revolutionized medicine.
"Horse owners provide their horses with a number of substances dangerous to human health.
A number of substances in this group are derived from algae, among them algin, carageenan, and agar.
Values of the heat of formation for a number of substances are given in Table A.9 in SB&VW.
Two men, aged 20 and 22, and a 16-year-old girl, all from Liverpool, were believed to have taken a number of substances, including Geebs.
"A decline in use already was under way for a number of substances, including cigarettes, inhalants, LSD and others," Professor Johnston said.
Doctors later ruled out poisoning by a number of substances and noted that his condition was consistent with a form of cancer.
After the rats ran, the researchers measured the levels of a number of substances in their leg muscles.
The general term "pesticide" includes a large number of substances that belong to many different chemical classes.
A number of studies expressed reservations though, acknowledging study limitations such as lack of reliable exposure data, limited number of samples and/or limited number of substances investigated.
The chemical analyses showed the presence of a large number of substances in rubber granulate, including various PAHs, phthalates, metals, benzothiazoles and phenols.
