"by fraction of" is a correct and usable phrase in written English.
You can use it when referring to one part of a whole or a percentage of a number. For example, "The population has increased by a fraction of 10% since last year."
Over the years, the device has only continued to grow, fraction of an inch by fraction of an inch.
As endoglucanases act on the surface chains, their activity is not severely affected by fraction of chain ends; however, degree of crystallinity plays an important role in deciding their performance.
Cu levels in sediments at the same sites were strongly influenced by fraction of clay (<63 μm) material but also by whether the samples were collected at an anchorage or control site.
The five most abundant prey taxa by fraction of individual prey items were adult Chironomidae (60%), Harpacticoidea (8.9%), pupal Chironomidae (7.7%) gammarid Amphipoda (6.2), and larval Chironomidae (5%).
‡ PaO2 divided by fraction of inspired oxygen.
An Immunoreactive Score (IRS) was calculated by multiplying "staining intensity score" by "fraction of positive cells"[ 22].
Gone was the rhythm of the page, replaced by fractions of a digital file.
She missed the birdie putt by fractions of an inch — an ordinary conclusion to a remarkable achievement.
With races determined by fractions of a second, runners have long looked to any advantage — banned or not.
Peter Neyroud, from the centre for criminology, University of Oxford, who specialises in policing, said: "While some of these forces have just increased by fractions of a minute these are annual averages and could be masking some serious lapses.
The radiation fell on the detectors, which heated up and cooled down by fractions of a degree as they were directed toward warmer and cooler parts of the cosmic ripples.
