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1.
反相胶束微反应器及其制备纳米微粒的研究进展   总被引:42,自引:0,他引:42  
对反相胶束微反应器的原理,模型和胶束内核水特性等方面的研究进行了评价,介绍了微反应器制备纳米微粒的研究进展。  相似文献   

2.
纳米反应器作为一种新型的制备纳米粒子及重要功能分子的手段,其技术在许多领域受到广泛重视.与常规意义上的化学反应器有所不同,纳米反应器是指反应所处的受纳米尺度调制的介观环境,如反应的介质、载体、界面等等.纳米反应器一般分成两类,一种是在分散相中能自组装的分子,形成有序聚集体,如胶束、囊泡,在聚集体的内部制备纳米粒子或材料;另一种是天然存在或合成的分子,如纳米管、树枝聚合物,利用分子特有的结构或孔隙作为纳米反应器.本文主要介绍了胶束、胶束作为纳米反应器的分类;重点讨论了分子及聚合物胶束作为纳米反应器的特点,并对其研究进展及前景进行总结和展望.  相似文献   

3.
通过在毛细管内层叠层组装纳米沸石并固定脂肪酶来构建纳米沸石修饰的固定化酶微反应器通道,将纳米沸石良好的生物相容性和高的酶固定能力与微反应器反应效率高、扩散传质快等优点相结合. 以对硝基苯棕榈酸酯的水解作为探针反应对该微反应器内固定化酶催化水解反应动力学进行了研究和计算,并与普通反应器内同样的反应进行比较. 通过对比米氏方程参数,证实在微反应器内酶催化水解反应效率可比普通反应器内提高3倍以上并可提高酶和反应底物的亲和能力.  相似文献   

4.
将钯催化剂负载在介孔硅材料的纳米孔道中,从而将催化的Heck偶联聚合反应引导至纳米限域反应体系,利用纳米孔道的空间限域效应实现了对所合成的聚对苯撑乙烯(PPV)分子量的控制。在6种钯纳米反应器中催化己氧基取代二碘苯单体与二乙烯基苯单体的Heck偶联聚合反应,通过红外光谱确定聚合物主链为对位苯环和乙烯基交替的结构。由凝胶渗透色谱对所获得的PPV的分子量进行表征,证明钯纳米反应器催化体系催化聚合反应所得PPV的分子量分布均较均相催化体系更窄,PPV的多分散指数最低可达1.53。  相似文献   

5.
将直流电弧等离子体技术用于甲烷热解制备纳米碳管的过程,并用TEM、ICP-CAS、TGA对所得固相产物进行了分析表征。结果表明,纳米碳管生长在铁质反应器壁面上,直径在20 nm~50 nm之间,具有多种形态,形态较为奇特的有螺旋状纳米碳管和放射状纳米碳管。该方法的特点是可同时副产大量氢气,实现了甲烷裂解制氢与合成纳米碳管两个过程的耦合。  相似文献   

6.
用于纳米粒子合成的微乳液   总被引:17,自引:0,他引:17  
连洪洲  石春山 《化学通报》2004,67(5):333-340,348
微乳液作为纳米反应器的最大优点是可以实现纳米粒子尺寸控制。体系中水的含量、表面活性剂、助表面活性剂等都是控制粒子尺寸的可调因素,研究这些因素对所合成的纳米粒子尺寸以及产量的影响对于实际应用有重要的意义。本文评述了近年来相关的研究进展,对微乳液法在合成纳米粒子中的应用前景作了展望。  相似文献   

7.
基于DNA折纸技术,构建具有纳米尺度可寻址的新型DNA纳米反应器,是DNA纳米技术领域的一个最新研究思路和方向。它的优势首先在于其纳米定位能力,通过不同的化学或生物相互作用,已能够实现对包括化学小分子、生物大分子及人工纳米材料等的纳米级精确定位;其次,DNA折纸结构的丰富多样性,使构建纳米级仿生限域环境成为了可能;此外,DNA折纸结构本身的生物相容性及优良的产率,也保证了这一材料的可应用性。本文首先介绍了在DNA折纸结构上,对不同材料和分子进行纳米定位的一般方法和最新进展。然后,着重阐述了基于纳米定位技术,以DNA折纸结构作为纳米反应器,对一些化学、生化反应的成功调控。最后,基于现有的工作基础,我们提出了DNA折纸术纳米反应器概念在未来的发展方向及应用前景展望。  相似文献   

8.
无机纳米粒子因其在催化、磁学、光子学等方面的特殊性质而越来越受到关注,纳米粒子粒径及分布可以人为控制,由此能够改变与有机聚合物所形成的纳米复合材料性能,在各种无机纳米粒子/有机聚合物复合材料制备方法中,纳米反应器(Nanoreactor)技术正日益受到关注,与常规的作为化学反应特定场所的化学反应器不同,纳米反应器不是一般的具体的机械设备,  相似文献   

9.
蛋黄-蛋壳结构独特的纳米结构及特性,使其在很多领域中具有潜在的应用价值,因此近年来受到了广泛关注.本综述总结了使用蛋黄-蛋壳纳米结构作为纳米反应器的研究进展.从合成策略出发,主要强调最近五年合成蛋黄-蛋壳纳米结构的最新研究进展.通过光催化,甲烷重整和电催化等反应作为典型的反应过程,重点讨论蛋黄-蛋壳结构纳米反应器在催化领域的应用,并对该领域未来的发展进行了展望.  相似文献   

10.
蛋黄-蛋壳结构独特的纳米结构及特性,使其在很多领域中具有潜在的应用价值,因此近年来受到了广泛关注.本综述总结了使用蛋黄-蛋壳纳米结构作为纳米反应器的研究进展.从合成策略出发,主要强调最近五年合成蛋黄-蛋壳纳米结构的最新研究进展.通过光催化,甲烷重整和电催化等反应作为典型的反应过程,重点讨论蛋黄-蛋壳结构纳米反应器在催化领域的应用,并对该领域未来的发展进行了展望.  相似文献   

11.
The mica microstructure is studied, and its shape and particle sizes are found as dependent on coating technology. Using epoxy and organosilicon polymers, several lots of materials with different contents of mica are prepared and mechanical tests are performed. The optimal amounts of mica wherein the initial strength characteristics are preserved are found. The thicknesses of epoxy and organosilicon polymer wherein high optical decorative properties of mica are preserved are determined.  相似文献   

12.
Abstract

Instrumental and manual methods currently available for the measurement of atmospheric oxidants are surveyed. Techniques used in the United States are emphasized and their advantages and disadvantages are discussed. Commercial systems are evaluated in terms of general operating principles rather than of specific instruments. The ability of these techniques to meet the measurement requirements defined by U.S. Federal air quality oxidant criteria are discussed. Alternative chemical techniques that may have some advantages over the neutral, buffered KI procedure are discussed. Also some attractive, alternative instrumental procedures that are ozone-specific are presented. These systems are based on chemiluminescence and ultraviolet absorption photometry. Electrochemical and colorimetric methods for total oxidant measurements are compared. Finally, some data are presented on relationships of ozone and total oxidants.  相似文献   

13.
14.
Spices and herbs are among the most commonly adulterated food types. This is because spices are widely used to process food. Spices not only enhance the flavor and taste of food, but they are also sources of numerous bioactive compounds that are significantly beneficial for health. The healing effects of spices are connected with their antimicrobial, anti-inflammatory and carminative properties. However, regular consumption of adulterated spices may cause fatal damage to our system because adulterants in most cases are unhealthy. For that reason, the appropriate analytical methods are necessary for quality assurance and to ensure the authenticity of spices. Spectroscopic methods are gaining interest as they are fast, require little or no sample preparation, and provide rich structural information. This review provides an overview of the application of NMR spectroscopy combined with chemometric analysis to determine the quality and adulteration of spices.  相似文献   

15.
Measurements of densities, speeds of sound, excess volumes and viscosities of binary mixture of methyl tert-butyl ether with tetralin and decalin are reported at 303.15?K over the entire range of composition. Excess volumes are measured using batch dilatometer technique. Sound speeds are obtained using ultrasonic interferometer. Densities are computed from excess volume data. Isentropic compressibilities are derived from density and sound speed data. Speeds of sound are evaluated on the basis of Jacobson's free length theory and Schaff's collision factor theory. The predicted values are in good agreement with the experimental results. The viscosity data are analysed on the basis of corresponding states approach. Excess volumes and deviation in isentropic compressibilities are negative and deviation in viscosities are positive over the entire composition range. The experimental results are discussed in terms of possible molecular interactions between unlike molecules.  相似文献   

16.
The major attribute of polyelectrolyte solutions is that all chains are strongly correlated both electrostatically and topologically. Even in very dilute solutions such that the chains are not interpenetrating, the chains are still strongly correlated. These correlations are manifest in the measured scattering intensity when such solutions are subjected to light, X-ray, and neutron radiation. The behavior of scattering intensity from polyelectrolyte solutions is qualitatively different from that of solutions of uncharged polymers. Using the technique introduced by Sir Sam Edwards, and extending the earlier work by the author on the thermodynamics of polyelectrolyte solutions, extrapolation formulas are derived for the scattering intensity from polyelectrolyte solutions. The emergence of the polyelectrolyte peak and its concentration dependence are derived. The derived theory shows that there are five regimes. Published experimental data from many laboratories are also collected into a master figure and a comparison between the present theory and experiments is presented.  相似文献   

17.
The rovibrational energy levels of methane are determined from a quartic ab initio potential energy force field where the expansion coordinates are the Morse coordinates for the stretches and extension coordinates for the bends. Energies are calculated using canonical Van Vleck perturbation theory. Results are obtained for both rotation-vibration Hamiltonians expressed as functions of curvilinear and rectilinear normal coordinates. Second, fourth, and sixth order curvilinear results are compared with experimental results, and fourth order results for the rectilinear and curvilinear Hamiltonian are compared to each other. The calculated rovibrational levels are in good agreement with the experimental values for low J levels. The calculated rotational level splittings are in even better agreement with the experiment. In particular, the ground state tetrahedral splittings, which are as small as 10(-4) cm(-1), are well reproduced by our calculations at sixth order.  相似文献   

18.
钼、钨系过氧化物是非常重要的Sharpless烯烃环氧化催化剂,有着非常广泛的工业发展前景。本文综述了钼、钨系过氧化物的种类,结构,合成方法及催化活性,分析了各种钼、钨系过氧化物的特点以及在催化环氧化领域的发展现状。同时,本文还讨论了钼、钨系过氧化物催化烯烃环氧化反应的机理。评述了在催化环氧化领域中两种主要理论——Mimoun机理与Sharpless机理的争论焦点及发展现状,以及计算化学对两种理论中间过渡态的研究进展,并且重点分析了Sharpless机理的过渡态结构。此外,本文还综述了影响钼、钨系过氧化物催化剂反应活性的各种因素以及质子所产生的副反应。最后,本文对应用于催化环氧化领域的钼、钨系过氧化物未来的研究方向提出了建议。  相似文献   

19.
20.
The structures, energetics, electronic properties, and spectra of hydrated hydroxide anions are studied using density functional and high level ab initio calculations. The overall structures and binding energies are similar to the hydrated anion clusters, in particular, to the hydrated fluoride anion clusters except for the tetrahydrated clusters and hexahydrated clusters. In tetrahydrated system, tricoordinated structures and tetracoordinated structures are compatible, while in pentahydrated systems and hexahydrated systems, tetracoordinated structures are stable. The hexahydrated system is similar in structure to the hydrated chloride cluster. The thermodynamic quantities (enthalpies and free energies) of the clusters are in good agreement with the experimental values. The electronic properties induced by hydration are similar to hydrated chloride anions. The charge-transfer-to-solvent energies of these hydrated-hydroxide anions are discussed, and the predicted ir spectra are used to explain the experimental data in terms of the cluster structures. The low-energy barriers between the conformations along potential energy surfaces are reported.  相似文献   

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