The phrase "activity of many different" is not correct as it is incomplete and lacks a noun to clarify what type of activity is being referred to.
You can use it when you want to describe a variety of activities involving multiple entities, but it needs to be part of a complete sentence.
Example: "The activity of many different species in the ecosystem contributes to its overall health."
Alternatives: "actions of various" or "engagements of numerous".
This review presents the utilization, modification, and determination of antibacterial activity of many different types of silver nanoparticles exhibiting AgNPs' versatility.
The genome sequence data suggests presence of genes encoding anaerobic metabolism and mechanisms to cause mucosal damage through the activity of many different virulence factors facilitated by chemotaxis and motility.
Chloride and other anions influence the structure and activity of many different proteins including opsins [19], intracellular Ca2+ channels [20], hemoglobin [21], [22], albumin [23], PDZ domains [24], K+ channels [25], [26], kainate receptors [27], serine/threonine kinases [28] [30], and G proteins [31].
The co-ordinated activity of many different cellular and biochemical mechanisms contribute to the development of a hypoxia-tolerant phenotype.
A disease outcome likely results from aberrant activity of many different molecular pathways, and thus it is likely that epigenetic modifications occur at multiple genes or genic regions.
Shallow sediments in surface waters receiving treated wastewater inputs are known to contain high μg/kg to low mg/kg quantities of TCS and TCC, levels that make impossible the survival and activity of many different species.
These processes happen at a multi-cellular level implying the coordinated activities of many different tissues.
Finally, human activities of many different types have combined to reduce the population number and size of many endemic species, in some cases resulting in extinction.
The overall p53 response of a cell thus depends on the integration of the signals and activities of many different mechanisms and proteins.
Secondly, FOXO activation results in increased PI3K PKB/Akt activity through regulation of many different genes (reviewed in [ 38]).
