一、河流流水作用 （一）水流的运动特征. 一在弯曲河道中,从凸岸由水面流向凹岸的水流构成一个连续的螺旋形向前移动的水流,称横向环流。横向环流的形成主要是由弯道离心力和地球偏转力的影响所致。弯曲河道由于水流本身偏转而产生离心力

酶是一种具有催化活性的蛋白质,因此酶具有催化剂的特点,即:能够加快特定反应 的速率但不能改变反应的平衡,在反应中不消耗,反应结束时回复到原来的形态;同时酶又 具有蛋白质的属性,即:酶由氨基酸通过肽键连接而成,只有在适当的温度,pH和离子强 度下才具有生物活性,有些酶还需要辅酶或者辅因子由于酶催化反应能够在常温常压下进 行,而且具有很高的效率和专一性,酶的应用日益受到了人们的重视

Teaching Points I. Background knowledge II. Introduction to the passage III. Text Analysis IV. Rhetorical devices V. Questions

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion

Teaching points I. Background information II. Introduction to the passage III. Text analysis IV rhetorical devices V. Questions for discussion