Sentence examples for been difficult to directly from inspiring English sources
Functional interactions between gene regulatory factors and chromatin architecture have been difficult to directly assess.
But for ethical reasons, it's been difficult to directly study the effects of nicotine exposure before birth.
Similar effects on the maturation of the cardiovascular system have been difficult to directly and non-invasively measure due to the small size of the embryo.
In terms of how my experience has been challenging, it's been difficult to directly measure the impact of the work we do.
This is particularly problematic in internally fertilizing species where it has been difficult to directly observe developing embryos.
The "hygiene hypothesis" is a plausible explanation for the increasing incidence of autoimmune and allergic diseases in affluent societies, but it has been difficult to directly elucidate the mechanism by which infectious agents such as nematodes alter disease-causing immune responses in humans.
It is difficult to directly measure body fat.
Postoperative patient motions are difficult to directly control.
However, it is difficult to directly utilize Lig's electroactivity, because of its insulativity.
Republicans acknowledged it was difficult to directly condemn Mr. Lieberman because of his reputation for moral rectitude.
