The phrase "at once perceived" is correct and usable in written English.
It can be used to indicate that something was recognized or understood immediately or simultaneously.
Example: "The beauty of the landscape was at once perceived by all who stood before it."
Alternatives: "immediately recognized" or "instantly understood".
Rendered as standard types of young soldiers, they were at once perceived not as portraits but as idealized superior beings, both because of their high rank and because they are souls beyond the grave.
As he noted, "I cut transverse sections though their pilei, examined these sections under the microscope, and at once perceived that in all the hymenial grooves and depressions the asci were curved outwards so that their opercula must have faced the strongest rays of light to which the ends of the asci has been subjected in the places where the fruit-bodies developed".
Women sought formal care only for conditions that did not improve with self-care or for conditions that were at once perceived to be severe, such as injuries, cardiovascular diseases, and diabetes.
The following day, Governor Butterworth wrote to the Government of India stating that the Government "will at once perceive that Pedra Branca is the only true position" for the lighthouse.
The legendary crime and western novelist Elmore Leonard, who died on Tuesday at 87, helped elevate literary genres once perceived as lowly into a respected and honorable pursuit.
And this trend, once perceived as a novelty at best, is attracting a new generation of light-traveling frequent fliers and canny frugalistas.
A hypothetical model based on the cumulative exposure to what was once perceived to be a low and "unconcerning" threshold at the time has now shown that radiation at all levels is cumulative across the population [4].
"Television was once perceived as a lesser medium," he says.
S_when Rec: perceived severity of Natech when received evacuation order; 14 Imm_evacuation: evacuated immediately once perceived the Natech; 15.
Closing Guantanamo was once perceived as a bipartisan moral imperative.
They experienced all events at once, and perceived a purpose underlying them all".
