景观变化包括景观的结构和功能随时间而变化。 变化既有自然的因素,也有人为的因素,变化有快 有慢。 比如:1976年唐山的大地震,一夜间。1978年的大 兴安岭大火,435万公顷。荷兰的围海造田、沙漠 化、滥伐森林等

3.4.1景观多样性 1生物多样性(biodiversity 生物多样性是所有生物种类、种内遗传变异和它们的生存环境的总和。 遗传多样性(genetic diversity)种内所有遗传变异信息的总和,蕴藏在动植物和微生物的个体基因里

一、肾脏的功能单位一一肾单位 二、肾单位的组成: 三、肾小球:滤过

Thus far, we have concentrated on the bending of shell beams. However, in the general case a beam is subjected to axial load. F · bending moments,M · shear forces,S torque(torsional moments)

Have dealt, thus far, with perfect columns, loading eccentricities, and beam-columns. There are, however, many more issues in buckling/(static) structural instability, most of which will try to touch on a) Buckling versus Fracture Have looked at columns that are long enough such that they buckle

Thus far have considered separately beam - takes bending loads column -takes axial loads Now combine the two and look at the beam-column (Note: same geometrical restrictions as on others

We have looked at basic in-plane loading. Lets now consider a second\building block of types of loading: basic torsion There are 3 basic types of behavior depending on the type of cross-section

We have thus far looked at In-plane loads torsional loads In addition, structures can carry loads by bending. The 2-D case is a plate, the simple 1-d case is a beam. Let's first review what you learned in Unified as Simple Beam Theory

第1章绪论 第2章数据类型和表达式 第3章控制语句 第4章函数 第5章数组 第6章指针 第7章结构体与共用体

Previously saw (in Unit 19)that a multi degree-of-freedom system has the same basic form of the governing equation as a single degree-of-freedom system The difference is that it is a matrix equation