after a quiet weekend without terrorist or military incidents encouraged bargain hunting, yet dealers emphasize that continued uncertainty will cloud future sessions. After dropping 14.3 percent last week, the Dow Industrials rose 367.63 on Monday, or 4.4 percent, to 8603.44. The Nasdaq Composite, which fell 16.1 percent last week, gained 75.92, or 5.3 percent, to 1499.11.