These compounds are made by the body but occur in concentrations too small to be collected for use as a drug.

Exocentric compounds occur more often in adjectives than nouns.

These lead compounds often occur with silver.

These compounds occur naturally in several fungi.

Such compounds can occur naturally, but are generally xenobiotic (man-made).

Instead, chemical fossils of unique lipids are more informative because such compounds do not occur in other organisms.

These compounds do not occur in nature.

Nominal compounds occur with various structures, however morphologically speaking they are essentially the same.

This compound also naturally occurs in brandy, capsicum, coffee, honey, pepper and some wine.

The compound is occurs naturally, including essential oils.