July 15, 1987

LEAD: The chairmen of the Congressional committees investigating the Iran-contra affair dismissed Lieut. Col. Oliver L. North from the witness stand this afternoon with stinging rebukes for having taken part in what they said was a policy based upon lies.

LEAD: A prominent anthropologist was sentenced yesterday to 40 years in prison for sending valentine boxes of poisoned chocolates to a Federal judge and to a professor.

LEAD: WITH more and more bans on smoking in public and in the work place and more and more nonsmokers adamant about their clean-air rights, smokers are coming under increasing pressure to quit. Nowadays a wide range of publications, programs and professionals are available to help smokers negotiate a life without cigarettes.

LEAD: ''This is an amiable day!'' said William H. Whyte, urban anthropologist, walking down the Avenue of the Americas during the lunch hour yesterday on one of his schmooze patrols.

LEAD: Falling short of Wall Street's optimistic projections, the International Business Machines Corporation said yesterday that its profits in the second quarter had dropped 9.9 percent.