Chemistry laboratories,and how they might be studied

Chemistry laboratories, as buildings, have been surprisingly little studied by historians of science; interest has been focused on them more as sites of specific scientific activity, with particular emphasis on the personalities who worked within them. This has overshadowed aspects of laboratories such as their specification, design, construction, fitting-out, adaptation, replacement, status as civic and academic structures, and so on. Systematic study of them would be aided by an agreed taxonomy of laboratory types, according to their purpose, and a scheme is proposed here. Practically no pre-1800 chemical laboratories survive, and there are very few dating from earlier than 1900, at least in their original state. Encouragingly, there have been several recent archaeological excavations which have turned up interesting evidence of early examples from various cultures. Little interest has been shown in the preservation of laboratories as significant architectural or historical structures, certainly when compared with other building types. The paper closes by considering those English laboratories which enjoy some level of legal protection but questioning the criteria adopted in deciding the programme of preservation.     

现代农业背景下的我国棉农技术创新行为的影响因素分析

选取棉花节水滴灌技术和机械化采棉技术为研究对象,根据869户棉农调研数据,采用Logtistic模型对影响棉农采用轻简化生产技术的影响因素进行了计量分析。结果表明,中国棉农的技术创新行为受到多种因素的影响。其中,技术本身的经济收益特征因素是关键因素,外部制度环境因素是重要因素,棉农自身特征因素的影响相对较弱。     

科研生产联合体属性的探讨

本文从国外国内方面综述了科研生产联合体产生的背景和形成的原因;运用系统观点对它的属性作了论述,并提出分析属性的三维结构图,数学模型;在总结联合体必备条件的基础上,就科研生产联合体定义问题进行了探讨。     

东北鼢鼠食性及食量研究

1988年在黑龙江省泰来县,使用笼内饲养观察的方法,对东北鼢鼠食性及食量进行了研究。结果表明,在饲喂的22种植物中只有野艾蒿不取食,最喜食苦荬菜、茵陈蒿。食量及食量指数取食多种植物远远高于取食单一植物。雌性食量指数高于雄性。     

从美国社区学院看我国高等职业技术教育的改革方向

美国创建和发展社区学院的成功经验 ,加上政府多种方式的助学计划 ,为全美快速从精英高等教育走向大众高等教育 ,并继而向普及高等教育发展推进 ,发挥了重要作用。学习国际职业技术教育的先进经验 ,从而能以发展的眼光来思考我国的职业技术教育 ,从更深层次上思考职业技术学院的教育教学改革     

缺货补偿条件下的生产规划模型及算法

针对缺货补偿条件下有能力约束、多产品、多阶段制造系统的生产规划问题，以利润最大为目标，建立混合整数规划模型。通过对模型的等价转换，基于对偶理论将等价模型分解为相互关联的生产主问题和库存子问题，设计对偶分解算法进行求解。数值实例的计算结果，说明了算法的收敛趋势以及在计算时间方面的性能。     

The Single-Vendor-Single-Buyer Integrated Production-Shipment Model with Stock Dependent Demand Rate

In the integrated production-shipment models for the single-vendor-single-buyer system presented hitherto, the demand rate of items is treated as a constant. However, many researchers have observed that the presence of more quantities of the same product tends to attract more customers. This suggests that the demand rate should depend on the stock level. This paper presents a single-vendor-single-buyer production-shipment model with the stock dependent demand rate, based on the demand rate linearly depending upon the stock level at any instant of time.     

黄土高原粮食发展趋势及策略研究

根据建国以后黄土高原地区粮食生产进程经历了振荡期 (1949～ 196 4年 )、徘徊期 (196 5～ 1983年 )、增长期(1984～ 1997年 ) 3个阶段 ,分析了粮食发展趋势 ,预测了 2 0 0 0～ 2 0 30年 7个不同年份全区和分区粮食的总产 ,并在对黄土高原粮食生产进行综合考察与定位试验的基础上 ,结合区域各地粮食生产及地貌类型、土壤侵蚀程度、生态环境、农业生产条件和国家粮食政策 ,提出了粮食可持续发展的经济对策和技术对策 .     

多波长同时测定食品中4种合成色素

本文研究了紫外分光光度法多波长同时测定食品中合成色素的最佳测试条件,确定了各色素在该测试系统中的最佳波长。测定了各色素在不同波长的百分比浓度吸光系数,方法变异系数为:3.09％～6.62％,回收率为:96.4％～104.2％。     

从寒食清明诗看唐代风俗

寒食清明是唐代重要的时令节日之一 ,在唐诗中有着大量的描写寒食清明节的诗篇 ,从中显示出寒食清明节在唐代的风俗。这些风俗有的是对唐以前习俗的继承 ,如禁烟赐火 ;有的是对唐以前习俗的发展 ,如上坟扫墓 ;有的是对唐以前习俗的突破 ,如踏青游玩 ;还有的是对唐以前习俗的创新 ,如宴游文会