The phrase "numbers of studies" is correct and can be used in written English.
For example, "The numbers of studies conducted on the subject of climate change has dramatically increased in recent years".
There are limited numbers of studies on Dhat syndrome.
However, there are limited numbers of studies on application of this material in asphalt mixture.
Vast numbers of studies have now demonstrated the cognitive damage that living in poverty does to children.
Numbers of studies have shown that 3D-cultured cells demonstrate higher innate resistance to external stimuli than 2D-cultured cells44.
There are limited numbers of studies investigating the effects of SERMs in males.
For several years, increasing numbers of studies have highlighted the existence of movement variability.
The limited numbers of studies available suggest a considerable influence of soil properties on macrofauna distribution.
The last few years witnessed increasing numbers of studies on the preparation, mechanical and biological evaluations of these novel materials.
The removal of heavy metals using adsorption techniques with microwave-irradiated low-cost adsorbents has a few numbers of studies.
Therefore, increasing numbers of studies have used ThT to detect amyloid aggregation within solution, especially when using synthesised or truncated peptides24,25,26.
However, increasing numbers of studies have found evidence that links the cerebellum with nonmotor functions (Middleton and Strick, 1994, 1998; Paradiso et al, 1997; Schmahmann, 1998).
