The phrase "are generated mainly from" is correct and usable in written English.
It can be used when discussing the primary sources or origins of something, typically in a scientific or analytical context.
Example: "The results of the experiment are generated mainly from the data collected over the past year."
Alternatives: "are primarily derived from" or "are chiefly produced by".
River discharges were generated mainly from the middle and upper basin, due to high precipitation, low evapotranspiration, and alpine swamp land use/cover in those areas.
In 2013, the share of renewable energy sources in the overall primary energy production in Poland amounted to 11.9% and was generated mainly from solid biofuels (76.6%), including wood, waste wood, and wood residues (GUS 2015).
Thermogravimetric analysis coupled to mass spectrometry and Mössbauer spectroscopy show that CO2 was generated mainly from pyrolysis, SO2 was generated from aluminium sulphate used as a coagulant in the drinking water treatment but H2O resulting from the decomposition of lepidocrocite at high temperature is likely to be the main agent for the foaming effect.
It is known from literature that a-wave is generated mainly from photoreceptors [ 24], and b-wave from bipolar cells [ 25, 26].
The variability among 14 rice Xa21 gene members has been considered to be generated mainly from the rearrangements mediated by transposon-like elements [ 9].
Heparin-binding epidermal growth factor in peritoneal fluid is generated mainly from cancer cells and peritoneal mesothelial cells, which have the same origin as coelomic epithelium of the NO.
Cell biological and biochemical investigations have revealed nine CIA proteins, and an initial mechanistic model of their function has been generated mainly from work in the model organism Saccharomyces cerevisiae and in human cell culture.
Given the nonrandom distribution of SSRs in plant genomes, predominating in non-repetitive sequences [ 19, 54], it is possible that our data may represent an overestimate of the overall SSR density in the cucumber genome, since it was generated mainly from non-redundant genomic sequences.
