让学生担当政治课堂的“主演”

课堂是教师与学生共同演出的一场戏。在这出戏中如何进行合理的分工,是取得演出成功的一个重要前提。笔者认为,课堂应该让学生当主演,而教师是幕后的导演。导演应该最大限度地挖掘演员的潜能,让学生在课堂上当＂主演＂使课堂效果达到最好。     

Thermodynamic Performance Characteristics of a Brownian Microscopic Heat Engine Driven by Discrete and Periodic Temperature Field

A Brownian microscopic heat engine with a particle hopping on a one-dimensional lattice driven by a discrete and periodic temperature field in a periodic sawtooth potential is investigated. In order to clarify the underlying physical pictures of the heat engine, the heat flow via the potential energy and the kinetic energy of the particles are considered simultaneously. Based on describing the jumps among the three states, the expressions of the efficiency and power output of the heat engine are derived analytically. The general performance characteristic curves are plotted by numerical calculation. It is found that the power output-efficiency curve is a loop-shaped one, which is similar to one for a real irreversible heat engine. The influence of the ratio of the temperature of the hot and cold reservoirs and the sawtooth potential on the maximum efficiency and power output is analyzed for some given parameters. When the heat flows via the kinetic energy is neglected, the power output-efficiency curve is an open-shaped one, which is similar to one for an endroeversible heat engine.     

早熟蟠桃的胚培养

为克服早熟蟠桃品种胚发育不成熟导致的杂种出苗率低的问题,实验采用胚培养技术挽救杂种胚,以美国红蟠作母本,贵妃红、早露蟠和英勒尔作父本,配置杂交组合,果实商品成熟期采集杂种胚,经过60d的低温层积（层积）处理,灭菌后接种在添加不同浓度激素的—玛培养基上进行胚培养。结果表明：配方MS＋2mg/L6-BA＋1mg／L IBA有利于蟠桃杂种胚芽的生长分化;配方MS＋1mg／L 6-BA＋1mg／L IBA有利于蟠桃杂种胚培苗多丛芽诱导增值生长。     

政治学科如何培养学生规范答题的能力

随着我国新课改教材的全面实施，高考能力测试要求的提高和学生文字表达能力普遍较差的矛盾也就显现出来了。规范化答题问题越来越成为教师和学生普遍关注的问题。如何培养学生的规范答题能力，以适应新高考对学生答题规范化的要求，是本文所要探讨的。     

水处理生物学课程教学改革的探讨

水处理生物学是给水与排水工程专业的一门重要的专业基础课,该课程涉及领域广、知识点繁多而分散。为了提高教学质量,根据自身教学体会,结合给水与排工程水专业特点和需要,从教学内容、教学方法等方面对该课程进行了教学改革,并取得了良好的教学效果。     

重视文化产业的时代意蕴

在发展文化产业的时候,必须重视文化产业的时代意蕴,即推动文化产业进一步向前发展的精神价值取向。我们向外输出的文化符号必须要包含中华文化的核心价值,发挥文化之软实力,提升文化产业的时代价值,并给世界带来新的道德秩序。     

广播电视机房接地方法浅探

接地是保证广播电视设备正常运转的重要条件。接地的目的有两个方面,一是抑制干扰,保证机房设备系统工作稳定;二是保护设备操作人员的安全。在广播电视设备工作中,有时会产生一些信号串扰、噪声以及计算机系统死机等现象,这与设备系统的接地不良、接地方法不正确有很大关系。接地系统是否可靠,直接关系到广播电视设备工作稳定和人员安全。本文主要介绍广播电视机房接地的种类、功能、要求。     

鸡维生素D缺乏症的诊治

1984年10月,某市一养鸡专业户,发现一群5月龄的罗斯母鸡发生维生素D缺乏症。我们采取补充维生素D为主的治疗方法,疗效达98.73％。现将该病的诊疗情况报告如下。一、症状:鸡于10月4日发病,病鸡精神萎顿,食欲不振,站立不起,两脚向左右伸出或前后伸出,胸骨突变形,弯曲,有的龙骨嵴甚至呈“S”形,有的龙骨嵴向内弯曲,有的病鸡有身体坐于腿上的特殊姿势。     

Thermodynamic Performance Characteristics of an Irreversible Micro-Brownian Heat Engine Driven by Temperature Difference

Based on the master equation describing the particles jump among barriers, the expressions of current, efficiency and power output of the heat engine are derived analytically. The general performance characteristic curves are plotted from the numerical calculation. It is found that the power output-efficiency curve is a loop-shaped one which is similar to the one for a real irreversible heat engine. When the heat flow via the kinetic energy is neglected, the power output-efficieney curve is an open-shaped one which is similar to the one for an endroeversible heat engine.