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氧氟沙星的核磁共振波谱性质研究 总被引:2,自引:0,他引:2
结合1H, 13C NMR, DEPT, COSY, HSQC, HMBC谱和碳氟偶合裂分行为, 对酸性及碱性溶液中氧氟沙星(Ofloxacin, OFL)的1H和13C谱分别进行归属, 研究了哌嗪环亚甲基构成的AA'BB'复杂自旋体系中各H的化学位移. 发现噁嗪环上的甲基处于直立键; 5H在酸性溶液中化学位移移向低场, 这可能与形成C—H…O弱氢键有关; 在碱性溶液中, OFL的羧基变为羧酸根, 造成羧基和羰基周围碳原子上π电子重新分布, 导致相应C的化学位移和碳氟偶合常数发生明显变化. 相似文献
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Heterologous expression characteristics of Trichoderma viride endoglucanase V in the silkworm, Bombyx mori L 总被引:1,自引:0,他引:1
Li XH Wang MX Zhang P Hu JB Sun CG Liu XJ Zhou F Niu YS Malik FA Bhaskar R Yang HJ Miao YG 《Applied biochemistry and biotechnology》2011,165(2):728-736
Efficient degradation of cellulose needs a synergistic reaction of the cellulolytic enzymes, which include exoglucanases, endoglucanases, and β-1,4-glucosidase. In this study, we used an improved Bac-to-Bac/BmNPV baculovirus expression system, which lacks the virus-encoded chitinase cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV), to express the endoglucanase V (EG V) gene from Trichoderma viride in silkworm BmN cells and silkworm larvae, and analyzed the characteristics of the recombinant enzyme in silkworm larvae. The result showed that an around 36-kDa protein was visualized in BmN cells at 48 h after the second-generation recombinant mBacmid/BmNPV/EG V baculovirus infection. The crude enzyme extract from the recombinant baculoviruses-infected silkworms exhibited a significant maximum activity at the environmental condition of pH 5.0 and a temperature of 50 °C, and increased 39.86% and 37.76% compared with that from blank mBacmid/BmNPV baculovirus-infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 10.0 and at temperature range from 40 to 60 °C. The availability of large quantities of EG V that the silkworm provides might greatly facilitate the future research and the potential application in industries. 相似文献
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Sm金属富勒烯的高效提取和电化学性质研究 总被引:1,自引:1,他引:0
在金属富勒烯 [1]的形成过程中 ,存在从金属到碳笼的电子转移 .La系金属富勒烯中 ,金属原子转移 2或 3个电子给碳笼形成 + 2或 + 3价的金属离子和带有大量负电荷的碳笼 .尽管如此 ,金属富勒烯仍具有良好的接受电子的能力 [2 ,3] .大多数的 La系金属富勒烯 ( Y,La,Ce,Pr,Nd,Gd,Tb,Dy,Ho,Er,L u)的电化学方法研究表明 ,它们可以接受 5到 6个电子 ,但是 ,Sm的金属富勒烯的氧化还原性质尚未见报道 ,其主要原因是 Sm金属富勒烯的合成产率低 ,仅是 La金属富勒烯的 7% ,从而使得其分离非常困难 ,需要通过多步 HPLC循环才能得到 [4 ,5] ,高… 相似文献
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The title compound H3[PMo12O40]· 3C2H6O was prepared and characterized by X-ray crystallography, its i.r. spectrum, cyclic voltammetry and e.s.r. spectra. The anion of the title compound is a Keggin-type heteropoly structure based upon a central PO4 tetrahedron surrounded by 12 MoO6 octahedra arranged in four groups of three edge-shared octahedra Mo3O13. Weak hydrogen bonds exist between the organic solvent molecules and the heteropoly anion. The catalytic activity of the title compound was determined by the synthesis of butyl acetate. The conversion of n-BuOH reached 93.3% and the yield of MeCO2Bu-n was 92.0% when the ratio of MeCO2H to n-BuOH, catalyst amount, reaction time, reaction temperature were 2:1, 0.24% of the reactants (50 mg), 2.0 h and 115 120 °C, respectively. 相似文献
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以“海带中碘的提取”为例,提供文献让学生课前阅读,完成“海带中碘的提取”流程设计,并进行成果交流。在此基础上,进行方案实施,并进行总结评价。研究结果认为,将知识与实践结合,能够激发学生探究热情;将自主文献研究、方案设计、实验验证结合,可以培养学生的科学探究和创新能力;应该注重教-学-评一致性;需要进一步提高教师的实验实际操作能力和知识引导能力。 相似文献
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We demonstrate that Mo_6S_(9_x)I_x nanowires(MoSI NWs) can serve as an excellent signal-intensifying nanomaterial for highly sensitive and label-free detection of DNA by ultraviolet(UV) spectrophotometry.The DNA extinction at 260 nm was greatly enhanced after addition of MoSI NWs solute,and the extinction value was linear with DNA concentration in the range of 0.0289-11.68 μg/mL with the real determination limit of 28.9 ng/mL.The association of DNA with the nanowires was characterized by transmission electronmicroscopy and circular dichroic spectroscopy.The results illustrate that the UV response amplification of DNA in the presence of MoSI NWs is attributed to the greater DNA coverage on the MoSI NW surface and the conformational transformation of DNA due to interaction of DNA with MoSI NWs.MoSI NWs are a promising nano-structured material for developing ultrasensitive sensors for detection of DNA. 相似文献
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Polygonum amplexicaule D. Don var. sinense Forb. (Polygonaceae) (PAF) is a famous traditional herb used to treat fractures, rheumatoid arthritis, muscle injury and pain. The present study was designed to investigate a PAF derived-chemical compound emodin-8-O-β-D-glucoside (EG) on the proliferation and differentiation of osteoblastic MC3T3-E1 cell in vitro. A compound was isolated from PAF extract by HPLC and identified as emodin-8-O-β-D-glucoside (EG) by spectroscopic methods. EG significantly promoted cell proliferation at 0.1-100 ng/mL, and increased the cell proportion in S-phase from 16.34% to 32.16%. Moreover, EG increased alkaline phosphatase (ALP) expression in MC3T3-E1 cells at the concentration from 0.1 to 100 ng/mL and inhibited PGE(2 )production induced by TNF-α in osteoblasts at the concentrations ranging from 10-100 ng/mL, suggesting that cell differentiation was induced in MC3T3-E1 osteoblasts. Taken together, these results indicated compound EG directly stimulated cell proliferation and differentiation of osteoblasts, therefore this study preliminarily explored the pharmacological mechanism of PAF to promote the healing of bone rheumatism and various fractures. 相似文献
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采用铂微电极观察到了室温下(25±1)℃甲苯单一溶剂中C60和C70的六步单电子电化学还原过程.在甲苯中采用一般的有机相支持电解质溶解度差,电势窗口也不宽.实验结果表明,离子液体[Tetrahexylam-monium bis(trifluoromethylsulfonyl)imide,THA-Tf2N]在甲苯中具有良好的溶解度,因而可以作为这种非极性溶剂的理想支持电解质,并且该体系可以提供宽达3/3.7V(相对于二茂铁电对,Fe /Fe)的电化学还原窗口,这是在室温下实现C660-和C760-的电化学检测的主要原因. 相似文献