The phrase "are highly active" is correct and usable in written English.
It can be used to describe something or someone that is very energetic or engaged in a particular activity.
Example: "The researchers found that the participants in the study are highly active, engaging in various physical exercises daily."
Alternatives: "are very active" or "are extremely engaged".
Au-containing catalysts are highly active in diverse reactions, and their activity strongly depends on the dispersion degree of Au.
Theta GSTs have limited transferase activity towards xenobiotics but are highly active GSH-dependent peroxidases [ 10].
Interestingly, all three processes are highly active in cancer cells, under conditions of high metabolic activity [3].
Although both catalysts are highly active in SCR reactions, they exhibit very low NO oxidation activity.
"Gaullist networks are highly active on his behalf and he has the support of other astonishing and unexpected people".
Unlike the natural hormones, these synthetic steroids are highly active when taken orally as tablets.
All are highly active and need much room; most are pugnacious notably when paired toward other birds; and a few become good, though small-voiced, mimics.
And more are coming: In imaging studies, for instance, neuroscientists have identified cortical areas that are highly active when people suppress impulses or other behaviors.
All newly born stars are highly active, blowing powerful winds that clear the surrounding regions of the infalling gas and dust.
In this critical environment, the petrol, gas and electricity firms, many of which are highly active on the wholesale commodity markets, are acutely vulnerable to reputational damage should an inquiry conclude they have been rigging the system.
The body is particularly receptive to nutrients in the 30-minute window immediately after exercise, as the enzymes and transporters in our muscles responsible for glycogen and protein synthesis are highly active at this point.
