The phrase "marginal segment" is correct and usable in written English.
It can be used in contexts where you are discussing a small or less significant part of a larger group or market.
Example: "The company decided to focus on the marginal segment of the market that had been overlooked by competitors."
Alternatives: "niche segment" or "minor segment."
In the 70's, movies for children were, in essence, exploitation pictures -- cheap, tacky attempts to cash in on the tastes of a socially and economically marginal segment of the audience.
The Falls City on display in the courthouse during the trials of Thomas Nissen and John Lotter was a meaner, more marginal segment of the community than the Chamber of Commerce might have chosen to emphasize.
Media analysts in Britain speculated that the move by the younger Mr. Murdoch might presage the News Corporation's eventual exit from British newspapers, once a core holding but now an increasingly marginal segment, in financial terms, of the company's worldwide operations.
The effective centerline, which removes two marginal segments from the centerline, is divided by equal distance segments and points in-between segments are extracted.
Of the 33 operations, 19 involved saphenous vein grafting of either the main, posterior marginal, or acute marginal segments of the right coronary artery.
Similarly Ficus sarmentosa is an indigenous climber and its leaves are lopped for feeding all types of animals particularly by the marginal social segments occupying the steep terrain.
However, after the period of scarcity, the marginal social segments, particularly the sedentary tenants, still utilize the leaves of this evergreen tree for feeding their goats and calves.
Although the variation in the electrical performance between different segments is marginal in short pillars, this variation is exacerbated in longer structures.
The numerical results have shown that the effect of the initial prestressing level and the number of segments are marginal on the impact force time history but significant on the residual displacement and the damage of the column.
The successful vitrification of blood vessel segments using marginal conditions of slow cooling and rewarming, provide essential information for the development of scale-up protocols that is necessary when clinically relevant size samples need to be cryopreserved in an essentially ice-free state.
The remaining segments of marginal bundles of adjacent cells form two arc-like bundles (Figure 11) containing myosin II [33], which produce tangential tension in the zone of cell-cell contact in nontransformed epithelial cells.
