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静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。 相似文献
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核/壳结构纳米纤维是一种兼具核层与壳层优异性能的功能化复合纤维, 通常具有优于核层和壳层自身的性能, 如可控的机械强度和较好的热传导系数等。其特殊的结构极大地提高了纤维的使用价值, 拓宽了纤维的应用领域, 因此, 核/壳结构纳米纤维成为纤维领域的研究热点之一。静电纺丝技术因其简单有效的特点, 近些年来在众多纳米纤维制备技术中一直备受关注, 制备结构和形貌可控的核/壳结构纤维的方法对于指导其在实际中的应用尤为重要。本文系统介绍了以静电纺丝技术制备核/壳结构纳米纤维的方法, 主要包括单喷头相分离法、同轴静电纺丝法、乳液静电纺丝法以及模板法, 重点讨论了影响核/壳结构的主要因素以及核/壳结构对纤维性能的影响。综述了近几年来国内外关于可控核/壳结构电纺纤维制备的研究新进展及其在药物缓释体系、组织工程支架、多功能敷料、污水处理材料、疏水性材料等领域的潜在应用价值。 相似文献
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静电纺丝技术就是通过带电聚合物溶液或熔体的喷射来制备纳米纤维,是一种制备纳米纤维材料简单有效的技术。醋酸纤维素(CA)易溶于有机溶剂,常作为纤维素的替代材料应用于静电纺丝领域。本文总结了近年来国内外采用静电纺丝技术制备CA复合纳米纤维的研究新进展,重点介绍了CA/CNTs复合纳米纤维、CA/金属粒子复合纳米纤维、CA/金属氧化物复合纳米纤维、CA基载药复合纳米纤维、CA/PAN复合纳米纤维、CA/PVA复合纳米纤维、CA/CS复合纳米纤维等CA复合纳米纤维的研究进展以及潜在的应用领域。 相似文献
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利用静电纺丝技术构建了新型三维纳米通道系统。 在不同质量分数的聚苯乙烯(PS:Mw=1.3×105)溶液中加入一定量十二烷基磺酸钠(SDS),于不同电压下进行静电纺丝。 所得纤维在90 ℃加热粘连后,形成三维聚苯乙烯纳米网络模板,然后于聚二甲基硅氧烷(PDMS)预聚体(含10%交联剂)灌注进入上述模板并交联形成网络复合材料,再用二硫化碳超声除去聚苯乙烯纤维。 采用扫描电子显微镜、透射电子显微镜对纤维模板形貌和纳米通道进行了表征。 结果表明,质量分数为10%的PS溶液加入0.5%SDS,在20 kV电压下进行静电纺丝,得到直径为150 nm的纤维。 SDS的加入对纺丝纤维具有平滑作用,使得粘连的纤维模板更易去除,形成的三维纳米通道直径约160 nm,与纤维模板直径一致。 该类型纳米通道可以应用于医学药物载体、纳流控芯片等众多领域。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
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A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL. 相似文献
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A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献