中学生物实验现状的调查与分析

《生物课程标准》的颁布以及现代社会的发展要求,对实验提出了更高的要求和标准。那么当前的中学生物实验又是一个什么状况呢?为此笔者开展了一系列实际情况调查。     

碳源对氮素在不同潜流带介质中的迁移转化规律研究

通过室内土柱实验模拟氮素在不同沉积物的潜流带中迁移转化途径,选取粗砂、细砂、粉砂三种介质,以浓度为65.5mg/L的硝酸钾溶液为原水,研究硝态氮在不同沉积物的潜流带中的环境行为;再通过补充碳源,研究碳源对氮的迁移转化过程的影响。实验结果表明,在不同的沉积物介质中,氮的迁移转化不同,主要受介质孔隙度和介质中有机质的制约。由于粉砂介质中孔隙度较小,有利于微生物的附着,且有机质含量较多,反硝化作用和异化还原作用强烈,所以硝酸盐氮下降的最多,而在粗砂介质中孔隙度相对较大,不利于微生物附着,且有机质含量相对较低,反硝化作用和异化还原作用较弱,硝酸盐氮下降的较少。而添加碳源后,反硝化作用和异化还原作用增强,三根柱子中的硝酸盐氮都降到很低的值,说明碳源对潜流带中硝态氮的去除起着重要的作用。     

金属材料冲击实验教学分析

在材料力学实验教学中常用简支梁式冲击弯曲试验来测定材料的冲击韧性αk值。并显示试件缺口处的力学特性(韧性或脆性)。由于冲击实验受到多种内在和外界因素的影响,要想正确反映材料的冲击特性,必须在冲击实验中做到标准化和规范化。     

规范大学物理实验教学环节的思考与实践

本文从大学物理实验预习、实验操作、实验结果检查、实验报告撰写等方面,介绍了我校在规范大学物理实验教学环节方面的一些思考与实践。     

信息管理与信息系统专业“管理信息系统”实验教学探讨

作为信息管理与信息系统专业的核心主干课程,管理信息系统是一门综合性很强的学科。本文针对信息管理与信息专业的特点,根据管理信息系统课程的特点,分析了实验教学中存在的主要问题,对实验教学的改革与实践进行了探讨。     

Assessing recreation carrying capacity of the environment attributes based on visitors’ willingness to pay

Recreation carrying capacity (RCC) is one of the most important indictors used in measuring the usage limits for the forest park resources. However, the consensus has not been reached with respect to the RCC’s content and its measuring metrics. In this paper, we attempt to establish a new RCC theoretical framework based on the demand theory of the tourism product characteristics. In the process, the choice experiment and orthogonal design methods are used in questionnaire designs and the conditional Logit model is used for parameter estimates. More than 700 park visitors are surveyed for data collection at the Shenyang National Forest park of Liaoning province in China. The primary park attributes being considered encompass vegetation, coverage, water quality, number of rubbish on the park trail path, admission fees, and congestion. The carrying capacity threshold for each specific attribute is identified.     

How much to give? — The effect of donation size on tactical and strategic success in cause-related marketing

In cause-related marketing (CM), companies promise a donation to a cause every time a consumer makes a purchase. We analyze the impact of the size of this donation on brand choice (tactical success) and brand image (strategic success). Our results reveal different effects of donation size on these success measures. For brand choice, the effect of donation size is moderated by a financial trade-off for consumers, whereas the effect on brand image is moderated by donation framing. Specifically, we show that donation size has a positive effect on brand choice if consumers face no financial trade-off; i.e., if they do not have to choose between triggering a donation or saving money. The effect is negative if a trade-off exists such that higher donations come at higher costs. Brand image is enhanced by larger donations if the framing is nonmonetary (e.g., the campaign promises the provision of vaccinations), whereas donation size has a negative effect if donation framing is monetary (e.g., the campaign states the Euro amount). If campaigns use a combination of both frames, the effect of donation size on brand image has an inverted U shape. Our results suggest that CM enhances tactical and strategic success only if firms select the right donation size, taking into account donation framing and financial trade-offs.