The phrase "a study has demonstrated" is correct and usable in written English.
You can use it when referring to research findings or evidence that supports a particular claim or conclusion.
Example: "A study has demonstrated that regular exercise can significantly improve mental health."
Alternatives: "research has shown" or "a study reveals".
For the first time, a study has demonstrated that an anti-HIV pill can protect uninfected people from contracting the AIDS virus through sex.
A study has demonstrated how arthroscopy can assess the quality of reduction but needs a surgeon experienced with the arthroscopic technique [57, 58]; the argument is that if reduction is assessed directly, arthroscopic assessment prolongs anaesthetic and surgical time.
This is the first time a study has demonstrated that offshore East Coast wind energy can provide "a relatively reliable supply of smooth power," says environmental engineer Mark Jacobson of Stanford University in California.
More recently a study has demonstrated a "like begets like" phenomenon, in that colonization of a specific niche by particular keystone species results in "invasion" of that community by other phylogenetically related species [65].
A study has demonstrated SLO from invasive GAS lyse PMN [27], however this effect is likely due to complement activation by SLO [28] or PMN activation [29] but not due to cytotoxity of SLO itself as judged by their flow cytometry profiles which are distinct from ours (Figure 2A).
Recently, a study has demonstrated that DEPDC5 mutation was involved in focal epilepsy, a neurodegenerative disease.
A recent study has demonstrated a high-fat low-carbohydrate protein-permitted diet without fasting to yield an 84% success rate regarding suppression of normal myocardial glucose uptake.
A previous study has demonstrated a reduction of MDR transport function in highly radiosensitive oral squamous cell carcinoma cell lines by 48 or 72 h after irradiation [18].
A recent study has demonstrated a possible influence of physical effects on BMLs.
A recent study has demonstrated a role for NFAT signalling in tumorigenesis [ 3].
