The phrase "available only a fraction" is correct and usable in written English.
It can be used to indicate that something is accessible or obtainable in a limited amount or degree.
Example: "The new software update is available only a fraction of the time compared to previous versions."
Alternatives: "accessible only in part" or "offered in limited quantity".
The low alignment rates of Bowtie1 means that methods have available only a tiny fraction of the useful data, leading to less accurate results.
The analysis in this paper suggests that 10 years or more after a proven life-saving public health intervention becomes available, only a small fraction of countries in need in the developing world is likely to have access to it.
Yet biological evidence is available only in a fraction of cases, and studies have shown that the main causes of wrongful conviction are eyewitness errors and false confessions.
Only DEXA results of the lumbar spine were included, as results of hip DEXA were available only in a fraction of the patients.
Such ODE models are common in biology as cellular species often participate in more than one reaction and concentration measurements are available only for a fraction of the species.
When buying or selling large blocks, they will have to take the best price even if it is available for only a fraction of their order.
The authors show then that even if this overlap is available for only a fraction of the users, it is still possible to retrieve the information for a large part of the network.
Newly-available DNA evidence has allowed the exoneration and release of more than 15 death row inmates since 1992, but DNA evidence is available in only a fraction of capital cases.
A plethora of child care legislation has been passed over the past four decades but programs are still available to only a fraction of the children and families who need them.
DNA sequences were available for only a fraction of taxa potentially related to our target species.
