The phrase "at short intervals" refers to events or actions that occur frequently and in close succession. Some synonyms for this term include "frequently," "often," "regularly," "repeatedly," "routinely," and "steadily." Other similar expressions may include "at close range," "in quick succession," "in rapid succession," "at a fast pace," "in quick intervals," and "at a brisk rate." These terms imply a sense of urgency or high frequency, and may be used to convey the need for prompt action or attention to a particular matter. Choosing the appropriate synonym depends on the context and tone of the sentence, as well as the intended emphasis on frequency.