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1.
本文合成了1,3-取代方酸衍生物:1,3-双[4-二甲胺苯基]-2,4二羟基环丁二烯氢氧双内盐(DMCS),1,3-双[4-双十六烷胺苯基]-2,4二羟基环丁二烯氢氧双内盐(DHCS)。研究了DMCS和DHCS在不同溶剂中的光物理行为,估算了DMCS、DHCS的基态与激发态之间偶极矩差值。在CTAB胶束中,除DMCS单体分子外,DMCS形成了二聚体。在二氧六环-水体系中,研究了DHCS的簇集行为,并测定了DHCS的临界簇集组成(C_ψ)及临界簇集浓度(C_A)  相似文献   

2.
本文合成了1,3-取代方酸衍生物:1,3-双〔4-二甲胺苯基〕-2,4二羟基环丁二烯氢氧双内盐(DMCS),1,3-双〔4-双十六烷胺苯基〕-2,4二羟基环丁二烯氢氧双内盐9DHCS)。研究了DMCS和DHCS在不同溶剂中的光物理行为,估算了DMCS、DHCS的基态与激发态之间偶极矩差值。在CTAB胶束中,除DMCS单体分子外,DMCS形成了二聚体。在二氧六环-水体系中,研究了DHCS的簇集行为。  相似文献   

3.
集散控制系统的工程设计   总被引:2,自引:0,他引:2  
以DCS应用观战介绍了DCS的工程设计步骤:方程论证,DCS评估,DCS询价,技术谈判,合同签订,开工会议,系统设计,组态编程,安装高度现场投运,整理件,工程验收。  相似文献   

4.
DCS是一种新型控制系统,适用于大工业生产和复杂的过程控制。同DDC、SCC等传统的控制系统相比,它具有更多的更显著的优点,目前DCS在我国玻纤行业中的应用仍处于起阶段,但DCS的必行。本文结合公司一年多的实际使用情况,从原理出发,谈变DCS的主要优点,发展方向和设计选型时的一些注意事项,以便玻纤同行参考。  相似文献   

5.
P-苯乙烯磺酸钠(SS)水溶液辐引发自由基聚合在γ-环糊精(CD)存在下被加速。加速效庆随着γCD/SS比值增大而加强,在γ-CD/SS大于0.4后加速效应效应不受γ-CD浓度影响,它表明γ-CD与SS生成1:2复合物加速聚合反应,而α-CD与SS分子形成1:1包接物滞阻聚合反应。  相似文献   

6.
随着高新技术的发展,DCS更新换代很快。智能变送器,现场总线以及RISC技术的应用,将过程控制推向一个新的时代。把握住DCS的发展动态,克服选型中的主观随意性,是当前DCS应用过程中值得注意的问题。  相似文献   

7.
随着高新技术的发展,DCS更新换代很快。智能变送器,现场总线以及RISC技术的应用,将过程控制推向一个新的时代。把握住DCS的发展动态,克服选型中的主观随意性,是当前DCS应用过程中值得注意的问题。  相似文献   

8.
注塑模具标准模架数据库的开发   总被引:5,自引:0,他引:5  
塑模CAD中机械设计模具种类繁多,但基本上还是趋于标准化的,为使模具的模架及标准部件肯序调用,模架数据库管理系统(MDBMS)及标准部件数据库管理系统(SPDBMS)成为注塑模CAD系统中的关键问题。本文介绍了注塑模的CAD中的MDBMS及SPDBMS的目标和任务,MDBMS和SPDBMS应具有的功能和结构,其中的几何关键技术以及今后的展望。  相似文献   

9.
注塑模CAD中机械设计模具种类繁多,但基本上还是趋于标准化的,为使模具的模架及标准部件有序调用,模架数据库管理系统(MDBMS)及标准部件数据库管理系统(SPDBMS)成为注塑模CAD系统中的关键问题。本文介绍了注塑模CAD中的MDBMS及SPDBMS的目标和任务,MDBMS和SPDBMS应具有的功能和结构,其中的几何关键技术以及今后的展望。  相似文献   

10.
左国庆 《兰化科技》1996,14(3):199-203
针对我国化工企业DCS应用经验,对DCS选型、应用软件开发、DCS环境条件、人员培训、抗干扰等实用技术予以综合叙述。  相似文献   

11.
Plant waxes   总被引:5,自引:0,他引:5  
P. E. Kolattukudy 《Lipids》1970,5(2):259-275
The surface of plants is covered with a complex mixture of lipids, often in crystalline form, called plant waxes. The chemistry, biosynthesis, catabolism and function of plant waxes are reviewed. The most common components are hydrocarbons, wax esters, free fatty alcohols and acids. Ketones, secondary alcohols, diols, aldehydes, terpenes and flavones are also found. The major function of the wax appears to be protection of the organism from water loss and other hazards of the environment. The alkanes are formed from fatty acids either by elongation followed by decarboxylation or by head-to-head condensation between two biochemically dissimilar fatty acids followed by specific decarboxylation of one of them. Fatty acyl-CoA is reduced to the aldehyde which in turn is reduced to the alcohol. The alcohol is then esterified with acyl moieties from acyl-CoA or phospholipids. Plant waxes undergo very little catabolism in plants but animals can degrade them to a limited extent and microorganisms readily degrade them. One of six papers to be published from the Symposium on Natural Waxes, presented at the AOCS Meeting, San Francisco, April 1969.  相似文献   

12.
Plant lipids     
The literature on lipid composition of algae and higher plants is reviewed to August, 1964. The complex glycero- and sphingolipids which have been reported from these sources are cataloged, and reference is made to key papers relating to their characterization, structure, and distribution. Paper II in the series “Plant and Chloroplast Lipids.”  相似文献   

13.
简单地介绍了润滑脂黄油装置现状。针对润滑脂黄油装置能耗高和利用率低,提出具体的措施,为了提高润滑脂黄油装置热效率,降低动力成本。经过半年的实践,取得良好的社会效益和经济效益。  相似文献   

14.
Plant Secondary Compounds and Grasshoppers: Beyond Plant Defenses   总被引:5,自引:0,他引:5  
Modern grasshoppers probably evolved from polyphagous ancestors endowed with the ability to tolerate many plant secondary compounds. This tolerance involves various behavioral and anatomical adaptations. Polyphagous grasshoppers have a relatively low level of sensitivity to the taste of many secondary compounds, and, if they do respond to the taste, have the capacity to habituate. This gives time for the induction of detoxifying enzymes so that unpalatable but potentially nutritious plants may be eaten safely. Associative learning involving secondary compounds may be important in food aversion learning, enabling the insects to avoid foods that have inappropriate nutrients, for example. Learning is also involved when grasshoppers develop associations between the taste of chemicals in the surface waxes of plants and internal leaf chemistry, enabling them to make faster decisions about the acceptability of a plant. Anatomically, the midgut ceca of polyphagous grasshoppers have well-developed posterior arms, and it is possible that these are especially important in detoxification, while some species, in addition, have a specialized pocket region in which macromolecules accumulate to be eliminated from the body when the lining of peritrophic envelope is drawn out. Polyphagous species also have thick peritrophic envelopes to which various phenolics become adsorbed. Finally, the midgut environment contains surfactants that reduce tannin–protein complexing except at very high tannin concentrations. Some polyphagous species can utilize secondary compounds as defensive substances or, in one case, in cuticular sclerotization. Grass feeding has evolved on numerous occasions from these polyphagous ancestors, and it has been associated with a loss of many of the characters providing protection from secondary compounds.  相似文献   

15.
In India, eggs of the polyphagous noctuid moth Helicoverpa armigera on sorghum are parasitized to high levels by Trichogramma spp., but only rarely are parasitized eggs found on pigeonpea. This study was conducted to test whether volatile plant infochemicals contribute to the different parasitism levels observed on these two crops. In a four-armed airflow olfactometer, volatiles emitted by both sorghum and pigeonpea plants elicited a behavioral response form Trichogramma chilonis females. The parasitoids' response varied depending on the growth stage of the plant. Volatiles emitted by sorghum in the vegetative and reproductive stages arrested the parasitoids. T. chilonis females did not respond to volatiles from pigeonpea in the vegetative stage, but were repelled by volatiles from plants in the reproductive stage. Plants in the reproductive stage are preferred for oviposition by H. armigera. Thus, sorghum is attractive and pigeonpea repellent to T. chilonis females at the time when each plant is attractive to the host. This difference in the parasitoids' response may partly explain the different levels of egg parasitism reported from these two crops. The infochemicals involved in these plant–parasitoid interactions are discussed in the context of the current terminology.  相似文献   

16.
17.
Ice adhesion and accumulation are well known to cause serious problems for different structures such as wind turbines, power transmission and distribution systems, and aircraft. Development of coatings that can resist icing can solve many challenges in various areas of industry. This work was inspired by nature and ice resistivity and superhydrophobicity of plants leaves. Kale is a winter plant with superhydrophobic behaviors, which is normally known as an advantage for cleaning the leaves; however, this article reveals that kale leaves have special surface microstructures delaying the ice formation initiation making them good candidates for designing ice-repellent coatings. In-depth experimental analyses, IR thermography, contact angle measurements, and scanning electron microscopy of the leaves were performed to discover how different plants can prevent icing and further find an optimal design for an artificial ice-repellent coating.  相似文献   

18.
钟建江  王威  岳才军 《化学世界》2005,46(8):498-503
介绍了一个有趣的植物细胞次级代谢物多样性的课题,综述了植物细胞培养中次级代谢产物多样性的调控。作为典型事例,特别对三七细胞培养中诱导荆如何影响皂苷的生物合成,结合本实验室的最近研究结果,进行了阐述;并就诱导剂在信号传导途径中的作用进行了探讨。无疑这样的多学科交叉研究是当今生物化工学科的发展趋势。  相似文献   

19.
Jasmonate-Triggered Plant Immunity   总被引:1,自引:0,他引:1  
  相似文献   

20.
新型植物杀菌剂--苯并噻二唑类植物抗病诱导剂   总被引:5,自引:0,他引:5  
植物抗病诱导剂是近年来发现的一种新型植物杀菌剂,苯并噻二唑类(BTH)就是其中重要的一类。对近年来BTH研究情况作一简要综述。  相似文献   

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