November 17, 1987

LEAD: Neftali Valencia, a Colombian who has worked steadily since he arrived in New York City in 1980, should have been the perfect candidate for citzenship under the new United States immigration law. Instead he believed that applying would alert agents to an earlier run-in with the law and end with his being thrown out of the country.

LEAD: A 25-year-old registered nurse, who officials said was trying to pose as ''a hero,'' was accused today of injecting fatal amounts of muscle-paralyzing drugs into several patients at a hospital here.

LEAD: Government policies to reduce surpluses of cheese, milk and rice have succeeded so well that the Reagan Administration plans to cut distribution of these commodities in half in the coming year, Federal officials said today.

LEAD: ALZHEIMER'S disease, the brain disorder that robs millions of people of their memories and minds, is beginning to yield secrets at a pace that scientists call dramatic and exciting.

LEAD: Officials investigating the fatal crash of a Continental Airlines jet in Denver said yesterday that prime interest had focused on the hazards of snow buildup on early-model DC-9 aircraft such as the one that crashed Sunday.