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1.
大学基础化学网络课程建设   总被引:2,自引:0,他引:2  
刘军  蔡宏伟  陈蕾 《大学化学》2009,24(5):46-48
建设了大学基础化学网络课程。该课程具有完整的体系和内容,辅以各类丰富的资源和信息,应用了大量图片、动画、视频以及模拟实验等各种多媒体教学手段,具有良好的教学效果,可作为课堂教学的重要补充。  相似文献   

2.
光学活性和立体构象不同的氨基酸,具有不同的生理活性和作用,因此,实现氨基酸的有效手性分离具有重要意义。色谱法是常用的氨基酸手性分离方法,具有分离效率高、速度快、灵敏、成本低和绿色环保等特点,在氨基酸手性分离和检测领域应用广泛。本文综述了色谱法在氨基酸手性分离方面的最新进展,并对其发展趋势进行了展望。  相似文献   

3.
研究了炭化树脂负载杂多酸催化剂的制备方法,利用IR,SEM等测试方法对催化剂进行了表征,并以异丁烷与丁烯的烷基化作为目标反应,测定了催化剂的活性,初步实验结果表明,该催化剂具有机械强度好,活性组分溶脱量少,能保持基材球状,酸强度大且活性组分分布均一及对目标反应具有较高活性等特点,是一种具有较好应用前景的新型负载杂多酸催化剂。  相似文献   

4.
负载型TiO2-聚酰亚胺亲水复合膜的制备与分离性能   总被引:4,自引:1,他引:4  
王建伟  钟顺和 《催化学报》1997,18(4):306-309
采用溶解-流涎法,湿相转换法和干湿相转换法制轩了负载型TiO2-聚酰亚胺亲水复合膜,采用扫描电镜,红外光谱,压汞和透气性实验等手段对该膜的孔径分布,表面结构及扩散性能进行了表征,并讨论了制备亲水对膜孔结构的影响,实验结果表明,三种膜均具有很好的亲水性能,而干湿相转换膜具有良好的孔径分布和分离性能。  相似文献   

5.
从二氧化碳和环氧丙烷及异氰酸酯合成聚亚氨碳酸酯   总被引:2,自引:0,他引:2  
研究了二氧化碳,环氧丙烷和异氰酸酯的共聚合反应.并考察了反应条件,异氰酸酯加入量对共聚产率及共聚物的特性粘数、分子量分布及热稳定性的影响.实验发现,引入异氰酸酯具有扩链作用,而引入二异氨酸酯则具有明显的文化交联作用.由共聚物水解试验和光谱研究结果表明,共聚反应生成的是聚亚氨碳酸酯,而不是聚氨基甲酸酯.这种聚亚氨碳酸酯比聚碳酸亚丙酯具有较高的热稳定性.  相似文献   

6.
高效蛋白质浓缩剂的制备及浓缩作用的研究   总被引:3,自引:0,他引:3  
采用自由基水溶液聚合方法合成了超高分子量的丙烯酸(钠)聚合物。该聚合物具有高达几十倍至上千倍的吸水能力,通过适当控制聚合物的交联度使其成为具有一定孔径的网状物,可用于生物大分子,如:蛋白质溶液或其它生物提取液的浓缩。试验了用反透析法浓缩胰蛋白酶的方法,与直接加入浓缩法相比,能够更好地保持酶的活性。与传统的浓缩方法相比,用该方法浓缩蛋白质具有效率高,浓缩剂用量少的优点。  相似文献   

7.
卟啉介导抗癌药物研究   总被引:10,自引:0,他引:10  
卟啉是一类具有特别生物功能的化合物,对于增殖异常的组织具有一定的亲和 力.利用这一特性,合成了四—对羟基苯卟啉(Zn^Ⅱ)甲氨蝶呤衍生物,并使用红 外、紫外、质谱、核磁和元素分析等手段对该化合物进行了表征.做了该化合物在 细胞水平上抗艾氏腹水型肿瘤实验,其IC50值为0.28μg/mL。同时在小鼠体内做了 抗艾氏腹水型肿瘤实验,抑瘤率为75.82%.初步实验表明,该化合物具有良好的 抗癌体内外活性及较小的毒副作用.从配位化学的角度提出了该化合物具有良好的 抗癌作用的可能机理.  相似文献   

8.
考察了前文制得的水滑石及其焙烧产物在对甲酚氧化反应中的催化性能,发现经水滑石焙烧得到的具有尖晶石结构的复合氧化物比没有焙烧的具有水滑石结构的以及由单纯氧化物机械混合的样品具有更高的活性.同时由CoCuAl水滑石(3∶1∶1)经450℃焙烧后制得的样品具有最佳的催化活性,对羟基苯甲醛的收率可高达98.4%,在此基础上,对此反应建议了可能的反应机理.  相似文献   

9.
离子交换法分离乳酸   总被引:2,自引:2,他引:2  
本文在对多种吸附剂和离子交换树脂进行筛选的基础上,获得了一种对乳酸具有优良吸附性能的弱碱型离子交换树脂,测定了乳酸在该树脂上的离子交换平衡数据,建立了数学模型,研究了其它无机盐的存在对离子交换平衡的影响,同时测量了乳酸在该树脂上的交换速率和穿透曲线.上述研究对于乳酸分离,特别是从稀溶液中分离乳酸提供了一种新的方法,对其它有机酸的分离也具有参考意义.  相似文献   

10.
PYR树脂对甜菊糖的吸附与洗脱性能研究   总被引:4,自引:1,他引:4  
系统研究了PYR型树脂对甜菊糖的吸附与洗脱性能,并与目前国内应用于甜菊糖提取分离的某些商品化吸附树脂进行了比较。结果表明,PYR树脂比其它树脂具有更优的性能,其静态吸附容量比AB—8树脂提高25%,且吸附速度快,易于洗脱再生,是一种具有工业化应用前景的新型吸附剂。  相似文献   

11.
This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed.  相似文献   

12.
Atomic clusters characterized by finite size, low dimensionality, and reduced coordination number exhibit many novel properties that are very different from their bulk. As these clusters are assembled, their properties can be significantly altered due to the interaction of these clusters with each other as well as with their support. This paper provides a brief review of the cluster properties that are affected when clusters are deposited on metallic or organic substrates, isolated in matrices or in zeolite cages, coated with acetate ligands, or simply allowed to self-assemble without the presence of any reactive species. It is shown that the interface between the clusters and their support can play an important role on the properties of clusters as their unique characteristics do.  相似文献   

13.
One-component adhesives-sealants, mechanisms of their synthesis and cure, the most important fields of their application, and peculiarities of their production under actual plant conditions are described. The assortment of domestic adhesives-sealants and their main developers and producers are reported. The most important parameters of the properties of domestic one-component adhesives-sealants, Elastosil, Pentelast, Avtogermesil, and other grades, are discussed.  相似文献   

14.
Gold nanorods were prepared in high yields by using a one-step seed-mediated process in aqueous cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of silver nitrate. The diameters of the nanorods range from 3 to 11 nm, their lengths are in the range of 15 to 350 nm, and their aspect ratios are in the range of 2 to 70. The diameters of the Au nanorods obtained from one growth batch in CTPAB solutions decrease as their lengths increase, and their volumes decrease as the aspect ratios increase. The diameters of the Au nanorods obtained from one growth batch in CTBAB solutions first decrease and then slightly increase as their lengths increase, and their volumes increase as the aspect ratios increase. These Au nanorods are single-crystalline and are seen to be oriented in either the [100] or [110] direction under transmission electron microscopy imaging, irrespective of their sizes. To the best of our knowledge, this is the first report of the preparation by using wet-chemistry methods of single-crystalline Au nanorods with aspect ratios larger than 15.  相似文献   

15.
Stimuli‐responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi‐stimuli‐responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi‐stimuli‐responsive character of these polymers, which are still relatively little known compared to their single‐stimuli‐responsive counterpart.  相似文献   

16.
Lactacystin and salinosporamide A are fascinating molecules with regard to both their chemical structures and biological activities. These naturally occurring compounds are potent and selective proteasome inhibitors. The molecular structures are characterized by their densely functionalized γ‐lactam cores. The structure and biological properties of these two compounds are attracting the attention of many chemists as challenging synthetic targets. We discuss their synthetic strategies in this review.  相似文献   

17.
Summary Two oxidation procedures for the synthesis of silicabased aliphatic sulfonic acid cation-exchangers for HPLC are described. Several reaction conditions for oxidizing a terminal-bonded thiol with organic peroxides are provided along with their yields, capacities, reproducibility, and chromatographic behavior. Also, three methods for determining exchange capacity are discussed, and their relationship to the capacity factors of charged solutes is compared. The maximum capacity determined by the titration of the bonded silica was 0.34 meq/gram. The general problems of synthesizing cation-exchangers, measuring their efficiencies and exchange capacities, and evaluating their overall performances are outlined.  相似文献   

18.
Cyclodextrins (CDs) are cyclic starches containing α‐1,4‐linked glucose units. Commonly available α‐, β‐, and γ‐CDs have six, seven, and eight glucose units, respectively. They are well known for forming noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical, with diameters of ~0.5–1.0 nm. Warm water washing of crystalline CD‐ICs containing polymer guests insoluble in water or treatment with amylase enzymes serve to remove the host CDs and result in the coalescence of the guest polymers into solid bulk samples. When guest polymers are coalesced from their CD‐ICs by carefully removing the host CD lattices, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. In addition, molecularly mixed, intimate blends can be obtained upon coalescence of two or more normally immiscible polymer guests from their common CD‐ICs. Not only are the organizations and behaviors of bulk polymer samples significantly modified on coalescence from their CD‐ICs, but both are also maintained for significant periods of time even when heated above their Tgs and Tms, where their chains are mobile. Here, we discuss the long‐time, high temperature stabilities of the organizations and properties of bulk polymers coalesced from their crystalline CD‐ICs. While random‐coiling of their initially coalesced, largely extended, separated, and unentangled chains may be relatively rapid, we conclude that the subsequent slow establishment of homogeneous melts or phase‐segregated blends results from the extremely sluggish center‐of‐mass diffusion that must accompany full entanglement of their chains. Apparently, the process of entangling the largely separated and not fully interpenetrating randomly coiled chains initially coalesced from their CD‐ICs is particularly slow, much slower in fact than the center‐of mass diffusion of polymer chains in their fully entangled melts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1543–1553, 2009  相似文献   

19.
The optical properties of three linear conjugated oligomers (F-P, F-P-F, and P-F-P-F-P), where phenothiazine (P) and fluorene (F) groups arrange alternately, are investigated. With the enhancement of the π-conjugated system, their absorption and emission bands both gradually red shift, and their two-photon properties are also improved. Meanwhile, their fluorescence dynamic traces are analyzed with continuous rate distribution model, exhibiting that their decay rates gradually accelerate and the rate distribution width become narrower. The quantum chemical calculation offers their molecular structures and transition mechanism, showing that the enhancement of π-conjugated system should be responsible for tile improvement of two-photon properties.  相似文献   

20.
功能性两亲嵌段共聚物因自身独特的性质而在靶向输送、控制释放、分子识别等领域得到广泛的应用.本文对这类嵌段共聚物的合成方法、其胶束的形成机理、制备形式、表征手段以及一些常见的具有光学活性的两亲嵌段共聚物及其应用进行了综述.  相似文献   

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