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1.
对具有生物活性的N-1代1,2,4,-三唑类化的的研究开发进行了总结。对20余年来这一类化合物的研究状况,合成方法,构效关系以及开发前景进行了综述。  相似文献   

2.
负载型金属CO氧化催化体系的研究进展   总被引:5,自引:0,他引:5  
本文结合近年来我们的研究工作以及国内外相关研究,概述了负载型金属CO氧化催化体系的研究进展,并进一步展望了今后的研究、发展方向以及应用前景。  相似文献   

3.
对具有生物活性的N-1取代1,2,4-三唑类化合物的研究与开发进行了总结。对20余年来这一类化合物的研究状况,合成方法,构效关系以及开发前景进行了综述。  相似文献   

4.
我国固体无机化学的研究进展   总被引:8,自引:0,他引:8  
综合介绍了建国50年来,尤其是近20年来我国固体化学研究领域所取得的进展,阐述了该领域在合成方法上的更新以及不断向信息、能源、环保等应用领域提供的各种新材料。  相似文献   

5.
三七水溶性化学成分及其药理研究新进展   总被引:15,自引:0,他引:15  
综述了近年来三七水溶性化学成分及其药理作用特别是对神经生理活性研究的进展,对三七与人参展其它植物植物进行了比较,阐明了三七所含多肽哆肽成分研究的意义及可行性。  相似文献   

6.
本文系统地介绍了迄今实验所发现的微原子簇的奇异性质,概述了十多年来该领域的重要进展,并分析了理论研究现状。  相似文献   

7.
砷的形态和痕量分析研究新进展   总被引:10,自引:0,他引:10  
综述了1993年来砷形态和痕量分析研究新进展,包括分离、测定方法的进展情况,引用相关文献70篇。  相似文献   

8.
α—溴代芳基酮的还原脱溴是有机化学中一种非常重要的官能团相互转换,通常有机合成中经常采用的是由芳基酮来制备α—溴代芳基酮,而反过来由α—溴代芳基酮来制备芳基酮的研究甚少,现在对碲使α—溴代芳基酮的还原脱溴反应进行研究,不仅拓宽了碲的应用范围,而且对将...  相似文献   

9.
贾铮 《化学通报》2005,68(2):106-110,134
组合电化学是一种新的电化学研究策略,通过设计和构建大量多样性的电极阵列,并对其进行高通量筛选和表征,快速、高效地实现了体系的电化学研究。本文综述了近年来进行的组合电化学研究,重点介绍了组合光学筛选方法、组合电化学合成方法以及电化学平行筛选方法,并探讨了各种方法的优势和存在的问题。  相似文献   

10.
1,3,3-三硝基氮杂环丁烷合成研究的现状与进展   总被引:5,自引:1,他引:5  
叙述近年来国外对新的高能量密度材料1,3,3-三硝基氮杂环丁烷合成研究的情况与进展,介绍了六种新的合成路线并进行了评论。  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
The thermodynamics of adsorption has been studied of hydrolyzed modified polyacrylnitrile (HMP) in water solutions with a concentration ranging from 0.25 g/l to 2.00 g/l on bleached sulphate and unbleached and bleached sulphite celluloses at temperatures of 0, 20, 40, and 60 C.It has been established that with the rise in temperature, the amount of adsorbed polymer —(HMP) decreases. The values of the enthalpy change are negative and show a linear decrease with the increase in the amount of adsorbed polymer. The adsorption equilibrium is defined by the logarithmic isotherm of Tjumkin, valid for uniform heterogeneous surfaces.With the increase in the amount of adsorbed HMP the values of the entropy change become negative and linearly decrease. A compensation effect has been noticed which results from the simultaneous action of the entropy and energy factors.The values of the change of the chemical potential for the three types of cellulose are negative and linearly decrease with the increase in the amount of adsorbed HMP and with the rise in temperature.  相似文献   

13.
Surfactants have been historically used for cleaning artifacts, but it was only in the last decades that serendipitous approaches were replaced by research in the field of soft matter and colloid science. Surfactants are components of nanostructured fluids, which were assessed for the removal of soil and aged coatings from paintings and are fundamental in processes that range from the inclusion of grime in micelles to the swelling and dewetting of polymer layers. Intriguing aspects involve the synthesis and use of biodegradable and self-cleavable surfactants, and the confinement of nanostructured fluids in gels, which boost the selectiveness of cleaning interventions. The performances of these advanced systems surpass those of traditional cleaning materials such as solvent blends and thickeners. The most important results are here reviewed and future perspectives given. Besides granting the transfer of cultural heritage to future generations, advanced cleaning materials are relevant to transversal fields, such as detergency, cosmetics, and drug delivery.  相似文献   

14.
Roraima is located in the extreme North of Brazil, in the Western Amazon Region. The groundwater has an important role in the public supply of potable water on the Roraima State. The objective of this work is the application of PCA (Principal Component Analysis) and HCA (Hierarchical Cluster Analysis) for the characterisation of tubular wells of the Roraima State, as regards physical–chemical composition of water. The parameters analyzed in laboratory were the following ones: pH, electric conductivity, Total Hardness, Total Alkalinity, Bicarbonate, Calcium, Potassium, Magnesium, Nitrate, Chloride, Total Iron. The physical–chemical analyses, were carried out during the months of September and October 2000 (winter, period of rains). The laboratory analysis was performed using classical methods (titrimetry and uv–visible spectroscopy), the samples were processed in agreement with the Standard Methods for Examination of Water and Wastewater.The physical–chemical analyses, were accomplished in September and October 2000. In physical–chemical terms, the groundwater samples analyzed do not indicate any restriction to human consumption and the two chemometric methods of exploratory data analysis: PCA and HCA are efficient for the discrimination of bicarbonated (tubular wells locateds in the South of the Roraima State) and not bicarbonated (tubular wells locateds in the North of Roraima) groundwater.  相似文献   

15.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

16.
Kinetics of thermal decomposition of hexanitrohexaazaisowurtzitane   总被引:1,自引:0,他引:1  
Thermal decomposition of hexanitrohexaazaisowurtzitane (HNIW) in the solid state and in solution was studied by thermogravimetry, manometry, optical microscopy, and IR spectroscopy. The kinetics of the reaction in the solid state is described by the first-order equation of autocatalysis. The rate constants and activation parameters of HNIW thermal decomposition in the solid state and solution were determined. The content of N2 amounts to approximately half of the gaseous products of HNIW thermolysis. The thermolysis of HNIW and its burning are accompanied by the formation of a condensed residue. During these processes, five of six nitro groups of the HNIW molecule are removed, and one NO2 group remains in the residue, which contains amino groups and no C−H bonds. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 815–821, May, 2000.  相似文献   

17.
This study presents the determination of the complexation capacity of phosphonates (ATMP, EDTMP, and DTPMP) by differential pulse polarography. All of them are non-volatile, stable in water samples, and resistant to hydrolysis. Therefore, their decomposition rate in natural water is low. The metal complexation capacity of these phosphonates was detected for cobalt, copper, and zinc ions. DTPMP is the best of the investigated chelating agents for these three metal ions.Owing to the environmental fate of aminocarboxylates, these were often replaced by phosphonates. Therefore, we compared NTA and EDTA with ATMP and EDTMP according to their Zn-CC and could find out approximately four times higher complexation of zinc ions by phosphonates than by aminocarboxylates.Furthermore, the interaction between phosphonates and the influence of iron ions on the Zn-CC were investigated by chemometric means. The design of experiments indicated no significant interaction in phosphonate mixtures but significant influence of iron ions. Thus, the complexation capacity of a mixture of ATMP, EDTMP, and DTPMP can be calculated by the addition of several individual Zn-CC of the phosphonates according to their percentage in the mixture. A similar calculation is impossible in the presence of iron ions.  相似文献   

18.
青海湖区河谷灌丛主要植物微量元素含量特征   总被引:2,自引:0,他引:2  
采集青海湖地区沙柳河河谷灌丛14种主要植物,采用AAS分析了其中7种微量元素含量。结果表明,元素Cu、Mn、Co含量有较大的植物种问差异,7种微量元素中Se含量最小,Fe含量最大。元素Mn和Fe、Co、Ni之间都具有极显著的正相关性,即相互之间具有协同性作用。  相似文献   

19.
Essential oils (EOs) have been used for centuries, and interest in these compounds has been revived in recent years. Due to their unique chemical composition as well as antimicrobial, immunostimulatory, anti-inflammatory and antioxidant properties, EOs are used in pharmacology, cosmetology and, increasingly, in animal breeding and rearing, and processing of animal raw materials. Essential oils have become a natural alternative to preservatives, taste enhancers and, most importantly, antibiotics, because the European Union banned the use of antibiotics in metaphylaxis in animal husbandry in 2006. In the animal production chain, EOs are used mainly as feed additives to improve feed palatability and increase feed intake, improve animal resistance and health status, and to prevent and treat diseases. Recent research indicates that EOs can also be applied to sanitize poultry houses, and they can be used as biopesticides in organic farming. Essential oils effectively preserve meat and milk and, consequently, improve the safety, hygiene and quality of animal-based foods. Novel technologies such as encapsulation may increase the bioavailability of EOs and their application in the production of food and feed additives.  相似文献   

20.
自由基聚合是《高分子化学》课程的重要一章 ,其中 ,平均聚合度是自由基聚合微观动力学的重要研究内容。正确理解其概念 ,掌握各种数学表达式的涵义 ,对高分子化学的学习十分有益 ,本文对不同终止和链转移情况下平均聚合度的表述方法进行了讨论  相似文献   

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