Their effect on cardiac contractility has not been assessed directly. 它们对心肌收缩性的作用未被直接评价过。
Macromolecule materials are added into urea-formaldehyde-resin todecrease its brittleness and contractility, and increase its water-resistance. 在脲醛树酯中加入其它高分子材料,降低其脆性和收缩性,提高其耐水性。