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991.
992.
邻苯三酚在碱性溶液中的自氧化反应产生超氧阴离子自由基(O2-.),可迅速氧化天青Ⅰ褪色。中药提取物可以抑制O2-.氧化天青Ⅰ褪色,根据该原理建立了一种测定中药对O2-.清除率的新方法。测定体系最佳实验条件为pH 9.0,天青Ⅰ用量为5.0 mL,邻苯三酚用量为0.8 mL,反应时间9 min。测得六种中药的提取液清除O2-.的效果,结果表明,清除能力顺序为:车前子>枸杞>川芎>当归>茯苓>射干。 相似文献
993.
John Texter 《Macromolecular rapid communications》2012,33(23):1996-2014
Stimuli responsiveness in polymer design is providing basis for diversely new and advanced materials that exhibit switchable porosity in membranes and coatings, switchable particle formation and thermodynamically stable nanoparticle dispersions, polymers that provide directed mechanical stress in response to intensive fields, and switchable compatibility of nanomaterials in changing environments. The incorporation of ionic liquid monomers has resulted in many new polymers based on the imidazolium group. These polymers exhibit all of the above‐articulated material properties. Some insight into how these anion responsive polymers function has become empirically available. Much opportunity remains for extending our understanding as well as for designing more refined stimuli‐responsive materials. 相似文献
994.
Vasko Jovanovski German Cabañero Hans Grande David Mecerreyes 《Macromolecular Symposia》2012,311(1):77-82
Summary: Two separate synthetic routes of preparation of new pyrrolidinium-based polymeric ionic liquids were compared. The first method utilized the modification of a commercial poly(diallyldimethylammonium) chloride via a direct anion exchange with several anions. The second route involved the anion exchange leading to several diallyldimethylammonium ionic liquid monomers having different anions and a subsequent polymerization. The latter method is particularly interesting for attaining tunable copolymers according to the desired properties of PILs. Both methods successfully resulted in ionic liquid polymers that are finding their way in a wide range of emerging applications. 相似文献
995.
The interplay between two important noncovalent interactions involving aromatic rings is studied by means of high level ab initio calculations. They demonstrate that synergistic effects are present in complexes where anion-pi and hydrogen bonding interactions coexist. These synergistic effects have been studied using the "atoms-in-molecules" theory and the Molecular Interaction Potential with polarization partition scheme. The present study examines how these two interactions mutually influence each other. 相似文献
996.
以硫酸铵(AS)水溶液为反应介质、聚乙烯吡咯烷酮(PVP)为分散剂进行丙烯酰胺(AM)与丙烯酸(AA)的分散聚合,制备了阴离子型聚丙烯酰胺(APAM).研究了硫酸铵浓度、单体配比、体系pH和分散剂PVP用量等对聚合产物特性黏数、溶解时间、聚合分散液的表观黏度的影响.得到优化条件:w(AS)=0.26,w(PVP)=0.04,m(AM)/m(AA)=4,pH=6.5.利用傅里叶红外光谱和光学显微镜对所合成的分散液进行了结构表征和形态分析,表明生成的产物是微球表面较光滑的APAM分散液. 相似文献
997.
Ray L. Frost Henry J. Spratt Sara J. Palmer 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,72(5):984-988
Near-infrared (NIR), X-ray diffraction (XRD) and infrared (IR) spectroscopy have been applied to hydrotalcites of the formula Mg6 (Fe,Al)2(OH)16(CO3)·4H2O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio. Such hydrotalcites were found to show variation in the d-spacing attributed to the size of the cation. In the IR (1750–4000 cm−1), the position of all bands except those at approximately 3060 cm−1 shift to higher wavenumbers as the cation ratio increases. Conversely, at wavenumbers below 1000 cm−1, the bands shift to lower wavenumbers as the cation ratio increases. A water bending mode at higher wavenumbers was also observed which indicates that the water is strongly hydrogen bonded. In the NIR spectrum between 8000 and 12,000 cm−1, there is a broad feature which is attributed to electronic bands of the ferrous ion and low intensity sharp bands due to overtones of the OH stretching vibrations. It is also apparent from this region that Fe2+ substitutes for Mg2+. The intensity of bands at 7750 and 5200 cm−1 increases as the cation ratio increases in the NIR spectrum. Hydrotalcites with a magnesium amount 3 and 4 times greater than that of aluminium and iron combined, in the lower wavenumber region of the NIR spectrum, have very similar spectral profiles. This work has shown that hydrotalcites with different divalent/trivalent ratios can be synthesised and characterised by infrared spectroscopy. 相似文献
998.
Two routes to RFIF6 compounds were investigated: (a) the substitution of F by RF in IF7 and (b) the fluorine addition to iodine in RFIF4 precursors. For route (a) the reagents C6F5SiMe3, C6F5SiF3, [NMe4][C6F5SiF4], C6F5BF2, and 1,4-C6F4(BF2)2 were tested. C6F5IF4 and CF3CH2IF4 were used in route (b) and treated with the fluoro-oxidizers IF7, [O2][SbF6]/KF, and K2[NiF6]/KF. The observed sidestep reactions in case of routes (a) and (b) are discussed. Interaction of C6F5SiX3 (X = Me, F), C6F5BF2, 1,4-C6F4(BF2)2 with IF7 gave exclusively the corresponding ring fluorination products, perfluorinated cyclohexadiene and cyclohexene derivatives, whereas [NMe4][C6F5SiF4] and IF7 formed mixtures of C6FnIF4 and C6FnH compounds (n = 7 and 9). CF3CH2IF4 was not reactive towards the fluoro-oxidizer IF7, whereas C6F5IF4 formed C6FnIF4 compounds (n = 7 and 9). C6F5IF4 and CF3CH2IF4 were inert towards [O2][SbF6] in anhydrous HF. CF3CH2IF4 underwent C-H fluorination and C-I bond cleavage when treated with K2[NiF6]/KF in HF. The fluorine addition property of IF7 was independently demonstrated in case of perfluorohexenes. C4F9CFCF2 and IF7 underwent oxidative fluorine addition at −30 °C, and the isomers (CF3)2CFCFCFCF3 (cis and trans) formed very slowly perfluoroisohexanes even at 25 °C. The compatibility of IF7 and selected organic solvents was investigated. The polyfluoroalkanes CF3CH2CHF2 (PFP), CF3CH2CF2CH3 (PFB), and C4F9Br are inert towards iodine heptafluoride at 25 °C while CF3CH2Br was slowly converted to CF3CH2F. Especially PFP and PFB are new suitable organic solvents for IF7. 相似文献
999.
We developed a new method consisting of the proteomic reactor coupled with step pH fractionation for the analysis of low-abundance proteins from minute amount of sample. These new reactors were implemented using both SAX and SCX materials. The pH fractions from the SAX reactor provided higher peptide and protein identification than SCX reactor and conventional solution digestion. Interestingly, the physical characteristics (pI, molecular weight, missed cleavage site and grand average hydrophobicity (GRAVY) index, and number of acid and basic amino acid) of the peptides obtained from the SAX and SCX proteomic reactors are drastically different. Furthermore, nearly half of the peptides observed from the pH fractionations from the SAX reactor are of low abundance while only 22% low-abundance proteins are observed with conventional in-solution digestion following 2D LC-MS/MS analysis. 相似文献
1000.
2-羟基-1-萘甲醛缩N-氨基-N′-苯甲酰基硫脲的合成及其阴离子识别性能 总被引:1,自引:0,他引:1
2-羟基-1-萘甲醛与水合肼缩合制得2-羟基-1-萘甲醛腙(2);2与硫氰酸铵和苯甲酰氯反应合成了2-羟基-1-萘甲醛缩N-氨基-N′-苯甲酰基硫脲(1),其结构经1H NMR,IR和MS表征。通过UV检测研究了1(DMSO溶液)对8种阴离子的识别作用。当1的DMSO溶液中存在F-,AcO-或H2PO4-时,颜色均由无色变为黄色,同时UV谱图发生显著变化;而加入C l-,B r-,I-,NO3-或HSO4-时,颜色及其UV谱图均无明显变化。结果表明1在DMSO溶液中对F-,AcO-或H2PO4-具有识别作用。 相似文献