'rare studies' is correct and can be used in written English.
It is used to refer to studies or research that is not widely known or widely covered. For example, "The professor completed a series of rare studies on the effects of sleep deprivation."
However, only rare studies have tried to prove the point.
It was one of the rare studies able to compare rates over time in the early period of AIDS and would have been impossible without Dr. Close, said Dr. McCormick, now dean of the University of Texas School of Public Health in Brownsville.
Currently, there are rare studies on quantitative identification of the steam breakthrough channel.
This review also reveals that rare studies have been done on CFD analysis of rectangular duct.
Rare studies have compared the toxicological effects of different types of nanomaterials, including carbonaceous, siliceous, and metal oxide nanoparticles.
These challenging factors have resulted on a rather rare studies of metal clusters deposited on nearly perfect HOPG substrates [8, 17].
In a rare study of drug addiction, conducted at Ibn Rushid several years ago, the researchers, Dr. Amir Hussein and Dr. Shalan al-Abbudi, found that cases of prescription drug abuse had increased substantially from 2002 to 2004.
Written by Leo Marks, this thriller is a rare study of the film-maker as committed (not to say deranged) loner, with Carl Boehm as a duffel-coated voyeur obsessed with capturing the look of terror.
A rare study is available about dorsal meningovertebral ligaments of the cervical spinal dura to the adjacent vertebrae.
Up to the present, rare study has been devoted to real-time analysis on gas products of anaerobic fermentation systems.
"This is a rare study," says molecular pharmacologist Ashim Malhotra of Pacific University, Hillsboro, in Oregon, who wasn't connected to the research.
