unambiguous evidence
unambiguous identification
unanaesthetized rats
unanswered

unanswered questions
unanticipated consequences
unanticipated effects
unappreciated role
unavailable

unavoidable consequence
unaware
unbaffled agitated vessel
unbalanced diet
unbalanced translocations

unbearable pain
unbiased
unbiased approach
unbiased estimates
unbiased estimation