There is therefore a close relationship between photochromic and thermochromic compounds.

Two authors of the report state a possible connection between estrogen-like compounds in the environment and increased incidence.

The timing of application and concentration varies between compounds.

The time interval between different compounds flowing out of the chromatograph was hard to control.

There is no clear dividing line between two-word compounds and pairs of words that simply happen to occur together quite frequently.

One major distinction is between natural and synthetic compounds.

The second distinction was between compounds and elements.

We left the riverbed and walked down an alleyway between compounds for about 50 yards.

For this reason a sharp boundary existed between organic and inorganic compounds.

The distinction between inorganic and organic compounds is not always clear.