The phrase "are mostly bound" is correct and usable in written English.
It can be used to describe a general state of being tied or restricted, often in a figurative sense, such as in discussions about obligations or limitations.
Example: "The participants in the study are mostly bound by their commitments to their respective organizations."
Alternatives: "are primarily constrained" or "are largely restricted".
The migrant birds that make it unscathed past Laotie Mountain are mostly bound, of course, for southeast Asia: a region well on its way to being clear-cut and strip-mined into one vast muddy pit, since China itself is hopelessly short on natural resources to supply the factories that supply us.
Both pigments are mostly bound to the PSI and PSII antenna proteins.
Circulating T4 and T3 are mostly bound to thyroxine-binding globulin, transthyretin, and albumin; < 1% is unbound and biologically active.
Circulating thyroid hormones are mostly bound to plasma proteins, with only a small amount circulating as free (unbound) hormones.
There are a number of studies dedicated to characteristics of sedation, but these studies are mostly bound to western country practices.
The drug and its active metabolites (monodesmethyl M1 and didesmethyl M2) are mostly bound to proteins and undergo hepatic metabolism by cytochrome P450 enzymatic system (isoenzyme CYP3A4), causing eventual interference with many drugs, specifically eryhtromycine and ketokonazole.
"This has been the lowest low for me," said O'Neil Sevin (pronounced SAY-vann), Stanley's father, whose 45-foot skimmer, Heaven Bound, has been mostly bound to its dock on Bayou Petit Caillou because prime fishing areas are closed.
Serum testosterone is mostly bound to the sex hormone-binding globulin and albumin.
The construct lacking the PEG chain only reaches cells at the nodule periphery and is mostly bound to the layer of extracellular matrix that surrounds the spheroid (A).
The nitrogen atoms were mostly bound to the graphitic network in two forms, that is, pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases.
In forest soils, Sb was mostly bound in residual fraction with "mobile" concentrations in the range of 0.6 4% of the total Sb content.
