变式教学在初中数学教学中的应用探析

变式教学法是在初中数学教学中普遍运用的一种教学方法,它主要是通过不同的角度对问题进行分析,从而寻找出问题的本质。在初中数学教学中对变式教学方法的运用不仅加深了学生对知识点的理解,还利于学生对知识点进行举一反三的应用,更加培养了学生的发散性思维,提高了学生的综合素质。从多角度介绍了变式教学法,并主要论述了变式教学法在初中数学教学中的应用问题。     

复杂剪式铰结构的几何分析和设计

本文分析了常见的一维和二维剪式铰结构的几何特点和可展条件，阐述了复杂剪式铰结构的设计方法和设计原则。以抛物面壳为例，介绍了用节点坐标为未知量分析复杂剪式铰结构几何问题的方法和几何设计的步骤。求解几何问题时，文中给出了简化迭代法。     

小学数学解决问题变式的设计原则研究

数学教育最根本的目标是培养学生独立思考问题、分析问题、解决问题的能力。因此,培养学生的创新意识及创新思维非常重要。变式题的训练有助于小学生发散性思维的发展,提高数学学习兴趣,加深学生对数学知识的本质理解等等。变式题的设计要符合趣味性、层次性、针对性原则,以便激发学生的数学学习兴趣,加深对相关知识内容的理解。     

以“变”促教,引领高效教学——例析初中数学变式训练的实施策略

数学作为基础性学科之一在学生的学习生活中占有重要地位,对学生未来的发展起到极其重要的作用。然而,在实际学习中,许多学生都对数学头疼不已,因此需要教师转变教学的方式方法,激发学生学习的动力。"变式训练"是数学教学的重要形式,举一反三,"变"的是表象,"不变"的是本质,教师在变式训练中引导学生发现不变的本质,从而能够真正掌握学习的规律,达到触类旁通的效果,教学事半功倍。因此,如何在教学中开展变式训练,达到以"变"促教的目的是教师需要重点研究的问题。     

空间可展剪式铰结构综述

空间可展结构是一种新型的工程结构,由于具备使用时可展开、不使用时可折叠收起或由部分刚体移动产生整体结构变形等特性,空间可展结构在临时性建筑及军工建筑中越来越得到重视,具有广泛的发展前景。文章从可展结构概念出发,简述可展结构在建筑工程中的发展历史;着重分析可展结构中的剪式铰单元结构的形成机理;对剪式铰可展结构进行分类;并总结几种空间可展剪式铰结构的几何外形;最后归纳了可展结构的发展前景和亟待解决的问题。     

善用高中数学的“变”，扬学生的智慧之帆

数学学习是思维活动,思考是主要的学习过程。高中生应对数学信息有较强的处理能力,对同一个知识点,有不同角度的考查。高中数学教学中,培养学生变式能力尤为突出,学生通过对概念、语言、公式、一题多变、一题多解等进行变式,从变化中找不变的规律,即"万变不离其宗",能对基本原理及其发展和应用信手拈来,多角度变式更能促进学生灵活的应变能力的发展,培养观察、思考、分析、归纳等良好的思维品质,提高学生对事物的探索精神和创造力,让学生扬起智慧之帆,在将来宽广的领域发挥聪明才智。     

研讨式教学法在土壤学教学中的探索与实践

研讨式教学法是由教师创设问题情境,然后学生查找资料,研究、讨论,提出解决问题的教学方法。笔者对土壤学课程进行研讨式教学法的探索与实践中,发现绝大部分学生喜欢并支持教师采用研讨式教学方法,支持比例达到91.8%,86.4%的学生能很好地参与研讨式教学,97.2%的受访学生认为设立研讨问题库是必要的,74.3%的受访学生认为能很好地提高自主学习意识和调动学习积极性及创造性,85.5%的学生认为"使我在遇到问题时能够很快很准的找出解决的切入点,并找出问题的关键",在对知识掌握程度方面研讨式教学法也比普通教学具有明显的优势。调查显示研讨式教学法最好的组织形式为"学生课堂讨论后老师再给答案",教师主动引导,带动学生参与,易被学生接受和产生良好效果。研讨式教学法应多增设理论联系实际问题进行研讨,适当指导学生掌握一些研讨方法,可采用师生同时在线进行研讨。     

变式教学在初中数学课堂中的实践

随着新课程教学改革的不断渗透,初中数学课堂的教学模式改革也取得了巨大的进步和发展,就我国当前的初中数学教学模式来看,变式教学的发展是非常具有时代特征和教学价值的。在初中数学教学课程中,变式教学可以帮助教师在课堂中引导学生进行数学知识的类比和迁移,让学生通过多元化的教学内容在不同的学习角度中理解数学问题,这样灵活的教学方式对于初中阶段的学生来说是非常有价值的,就变式教学在初中数学课堂中的实践进行简单的分析。     

变中激趣,趣中促效——中职数学多元表征的变式教学实践探究

本文以系统论、学习论、认知论为理论依托,阐述了中职数学多元表征的变式教学的基本功能、实践操作的要领和注意事项,并在实践的基础上对如何搞好中职数学多元表征的变式教学进行了反思与思考。目的是通过变式与多元表征相互作用来激发学生的学习热情,发挥教师主导、学生主体地位的作用,真正实现"以学定教"的核心思想。     

理解：关于高三数学复习的指向思考

高三的学生学习紧,任务重,教师在课堂上要质量,就要提高课堂的有效性,让学生学会理解,这样方能跳出题海,设计变式迁移,方能事半功倍,促进学生理解的能力。     

《标准施工招标文件》下变更估价原则应用研究

工程变更贯穿于整个施工过程中,站在业主角度,工程变更发生后,如何以变更估价原则为依据,准确判定变更估价原则的使用条件,选择适当的变更综合单价确定方法,直接关系到业主对工程造价的控制。以2007 版《标准施工招标文件》为研究基础,运用文献研究法找出变更估价三原则的使用条件,结合算例分析法为业主对已经发生的工程变更的综合单价确定提供一些依据,从而减少工程结算中的扯皮现象,也保证业主对工程价款管理的控制权。     

砼回弹法测强统计分析

简述了砼回弹法测强与抗压强度对比试验的方法，得出了影响砼回弹测强的种种因素，通过统计分析给出了砼回弹测强的实用计算公式，从而就可在结构物上直接进行回弹测强，达到及时，方便，准确地了解结构物的强度．     

Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China

Seasonal and diurnal variations of carbonyl compounds were investigated at two sampling sites (Liwan and Wushan) in the ambient air of Guangzhou, China. Air samples were collected during 2005 from January to November, and carbonyl compounds were analyzed with HPLC. The results show that carbonyls exhibit distinct seasonal variation. The total concentrations of 21 carbonyls detected ranged from 2.64 to 103.6 μg m⁻³ at Liwan and from 5.46 to 89.9 μg m⁻³ at Wushan, respectively. The average total concentrations of carbonyls at both Liwan and Wushan decreased in order of summer>spring>autumn>winter. Formaldehyde, acetaldehyde, and acetone were the most abundant carbonyl compounds, which accounted for more than 60% of the total concentrations of carbonyls. The mean concentration ratios of summer/winter were all > 1.0 for the total concentrations and the individual carbonyl compound. The diurnal variation of carbonyls was not distinct in this study. The average concentration ratios of formaldehyde/acetaldehyde (C₁/C₂) varied from 0.71 to 1.32 and 0.65 to 1.14 at Liwan and Wushan, respectively, and the average concentration ratios of acetaldehyde/propionaldehyde (C₂/C₃) varied from 5.42 to 7.70 and 5.02 to 13.9 in Liwan and Wushan, respectively. Regarding photochemical reactivity of carbonyls and the ozone production, acetaldehyde, butyraldehyde, formaldehyde, and valeraldehyde account for 75-90% to the total propene-equivalent concentrations, while formaldehyde, acetaldehyde, valeraldehyde, butyraldehyde, and propionaldehyde contribute 89-96% to the total ozone formation potentials (ranging from 105 to 274 μg m^-3). The ozone formation potentials in summer were higher by 1-2 times than those in the other seasons.     

Problems of Bed and Foundation Stability in the Magadan Oblast

Methods known in engineering geocryology for ensuring the stability of buildings and structures are presented. Causes of failure to fully consider natural and technical factors affecting variation in the geocryological situation in heavily developed areas, which may be aggravated by production errors during the installation and service life of beds and foundations, are discussed. Characteristic features of the development of emergency circumstances are examined, and a promising method is proposed for their prevention.     

浅谈健康高效、可持续发展的医疗建筑创作

信息时代是一个崇尚健康．高效．可持续发展的时代，而医院环境的人性化．智能化以及医院的可变性与这三个主题有着直接的关系，因此，信息时代的医疗建筑应该朝着什么方向发展．变化。成为十分重要的研究课题。     

Spatio-temporal patterns and source apportionment of coastal water pollution in eastern Hong Kong

The comprehensive application of different multivariate methods and geographic information systems (GIS) was used to evaluate the spatio-temporal patterns and source apportionment of coastal water pollution in eastern Hong Kong. Fourteen variables were surveyed at 27 sites monthly from 2000 to 2004. After data pretreatment, cluster analysis grouped the 12 months into two groups, June-September and the remaining months, and divided the entire area into two parts, representing different pollution levels. Discriminant analysis determined that NO3- -N, DO, and temperature and TN, SD, PO4(3-)-P, and VSS were significant variables affecting temporal and spatial variations with 84% and 90% correct assignments, respectively. Five potential pollution sources were identified for each part by rotated principal component analysis, explaining 71% and 68% of the total variances, respectively. Receptor-based source apportionment revealed that most of the variables were primarily influenced by soil weathering and organic pollution, nutrient pollution (or agricultural runoff), and mineral pollution. Furthermore, GIS further facilitated and supported multivariate analysis results.     

施工阶段工程变更签证对工程造价的影响

施工阶段工程变更签证的复杂性致使工程变更签证价款在工程造价中所占比重不断上升,文章结合工程实例探讨花工阶段工程变更签证对工程造价的影响,并提出控制措施.     

工程变更的分类控制

首先依据工程变更内容将工程变更划分为工作范围变更、施工条件变更、设计变更、施工变更和技术标准变更,对不同内容的变更区别情况提出不同控制方法。其次,依据工程变更性质将工程变更划分为重大变更、重要变更和一般变更,通过建立不同变更审批权限控制工程变更。最后依据工程变更的迫切性将工程变更划分为紧急情况下的变更和非紧急情况下的变更,通过设定不同变更处理程序进行控制。     

Seasonal cycle of VOCs in apartments

To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996-99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation.     

论工程变更与造价控制

本文结合笔者多年的工程变更的造价控制工作经验，对当前的工程变更中的造价控制工作的开展提出了如下几点建议，仅供参考。