化学检验分析前质量控制的影响因素

质量是产品市场竞争力的最有力的保障,而化学检验分析是产品质量的重要体现,因此随着市场竞争的日益激烈,化学检验分析越来越受到人们的重视。化学检验有较高的技术要求,加强化学检验分析前质量控制是检验结果的关键。对化学检验分析前质量控制的影响因素进行了探讨,旨在促进化学检验分析前质量控制水平的提高,确保检验结果的准确性。     

高校课堂教学的探讨与实践

大学课堂教学效果直接关系到一个学校的教育质量。本文从教学的中心主体学生这个视角出发,分析了影响学校课堂教学效果的内在因素,探讨并实施了相应的课堂教学改革举措,这些改革措施有效地培养了学生自主学习、主动思考的习惯,提高了学生自我学习、自我创新的能力。     

试论单指标评教法

提高教学质量是高校的主要任务之一。抓课堂教学以及加强对课堂教学质量的评估是提高教学质量的重要一环。根据实践是检验真理的唯一标准的哲学观点,笔者认为,“评教”在很大程度上取决于教学效果,而教学效果的公正性又取决于教考分开的考试制度。因此,教考分开的教学效果(某门课的考试成绩)可以作为课堂教学效果评估的唯一指标,即单指标评教法。     

化工建设项目生态环境影响评估

现今时期,我国工业化得到了有力发展,工业化进程的发展给环境问题造成了一定的影响。分析了化工建设项目对于生态环境的影响,对其给环境造成污染的重要因素进行评估,以降低化工建设项目对以后生态环境的影响。     

基于层次分析法固井质量评价研究

固井质量问题长期困扰油气田的高效开发,目前还有没确实有效的补救措施,固井质量预评价对于保障固井质量具有重要的作用。层次分析法是一种理论简单,工程应用性强的评估决策方法,可以对相互关联的众多因素复杂影响下的被评事物做出具有理论依据的合理评估。在全面考虑多层次影响因素的基础上,进行基于层次分析法因素分类,建立固井质量预测综合评价数学模型,提高了完井固井质量模糊预测的可信度。     

数学课堂教学中的计算机技术运用

分析在小学数学课堂教学中运用计算机教育技术,可以创设教学情境、激发学习兴趣、增强信息强度、突破教学难点、高效完成练习的优势,并提出计算机教育技术是知识传输的有效载体,是更新教学方法,实现课堂教学最优化的重要途径和有力措施,是实施素质教育,提高课堂教学效率的重要手段。     

理工科本科课堂教学质量评估指标体系研究

如何制定科学的课堂教学质量评估体系来评估教师的教学质量,是教育管理部门和教师都十分关心的问题。笔者对华中科技大学的理工科教师进行了随机抽样调查,并对调查结果进行了统计分析,初步制定出了理工科本科课堂教学质量评估指标体系。     

如何从教学方法入手提高生物学教学质量和效果

教学方法是影响课堂教学质量和效果的诸多因素中最为关键的一个,文章初步探讨了在生物教学实践过程中如何从教学方式、教学艺术、教学系统性和整体性、促进个性发展及教学科研相结合等五个方面来提高生物学教学质量和效果。     

基于新工科标准的本科工程人才培养质量影响因素调查

探索新工科人才培养质量的标准及其影响因素是“新工科”研究的重要内容。文章分别以学生传统课业成绩和新工科标准表现为因变量,基于本科工程人才培养质量影响因素框架,探讨了不同类型课程学分、课堂教学、教师教学、学生自身学习、课堂外学习、同侪等因素对两者的影响及其这些影响的差异性,为进一步提高工科人才培养质量提供了实证依据。     

影响岩心采取率质量的相关因素分析

岩石的质量受多种因素的影响,为了得到较高质量的岩心,需要全面了解影响岩心采取率质量的因素,积极采取相应措施,不断提高岩心采取率质量。本文分析了地质因素、机械操作因素、钻进过程影响因素、钻具结构因素和操作技术因素。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。