全部

1·Rooted in the physical principle of least action, they have wide applications in diverse fields.

在于最小行动的物理原理，他们在完全不同的领域有广泛应用。

2·If the physics seems a bit arcane, consider that you probably spent much of the past two weeks seeing the angular-momentum principle in action — at least if you watched the Olympics.

如果从物理学角度来讲解释这些原理有点晦涩难懂，那么在过去的两周内也许你也花费了大量的时间观看了角动量原则的实际演示--至少如果你观看了冬奥会比赛。

3·The existence and multiplicity results are obtained for a class of fourth-order nonlinear elliptic equations by the least action principle and the minimax methods, respectively.

通过极小化作用原理和极小极大方法得到了一类四阶非线性椭圆方程解的存在性和多重性。