The phrase "increased gently" is a valid and usable part of a sentence in written English.
You can use it to describe a slow and gradual increase of something. For example, you could say, "The temperature increased gently, but steadily, until it reached boiling point."
The scenario with an EIR of 1, however, increased gently to a maximum at 20 years.
We found that the overall inequalities in the distribution of health workers decreased to the lowest in 2000, then increased gently until 2011.
The overall inequalities in the distribution of health workers decreased to the bottom at 2000, then increased gently until 2011 (as Figure 1 shows).
From the beginning of the third stage of the medical system reform, the inequalities in the distribution of health workers increased gently until 2011, as a negative effect of continued medical market reform.
The curve increases gently when the sensor density is below 0.312 and grows rapidly as the density is above 0.312.
Tests results of G/L effect on CO2 removal efficiency show that, when G/L=1∼5, CO2 removal efficiency increases rapidly with the increase of G/L; when G/L=5, CO2 removal efficiency=80%∼88%; when G/L=8, CO2 removal efficiency=86%∼92%, when G/L>8, CO2 removal efficiency increases gently with the increase of G/L.
Increase in glycerol content decreased tensile strength sharply, while presence of Na MMT increased it gently.
However, with further increase of V/III ratio, the QD density increases gently.
The value of factor increase gently with the loads and adjustable rates.
From 1 to 5 min, the total thickness of the coatings increases gently and the total growth rate declines sharply; at this stage, the outward growth gradually slows down, and the inward growth maintains persistent enhancement.
v a for (e) gently increased as it approached the target position.
