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961.
A straightforward on-line monitoring of organic reactions by ultrasonication-assisted spray ionization mass spectrometry (UASI MS) is demonstrated in this work. 相似文献
962.
Yu CC Chen HW Chen MJ Chang YC Chien SC Kuo YH Yang FL Wu SH Chen J Yu HH Chao LK 《Natural product communications》2010,5(12):1941-1944
The present study investigated the chemical composition of Isochrysis galbana Parke, a marine microalga which is widely used as a feedstock in aquaculture. From gas chromatography/mass spectrometric analysis the mono-sugar compositions of I. galbana were 2.1% fucose, 2.5% rhamnose, 2.7% arabinose, 8.5% xylose, 15.7% mannose, 32.7% galactose and 35.8% glucose. The polysaccharides of I. galbana were able to induce prointerleukin-1beta (pro-IL-1beta) protein expression within murine macrophages. Furthermore, five kinds of chlorophyll and one sterol were separated from the ethanolic extracts, including pheophorbide-a, ethyl pheophorbide-a, 10S-10-hydroxypheophytin-a, 10R-10-hydroxypheophytin-a, (132-R)-pheophytin-a, and brassicasterol. In addition, the major soluble components of the ethanol/n-hexane extract were 9-octadecenoic acid (E) (38.4%), hexadecanoic acid (23.3%), tetradecanoic acid (15.7%), and octadecanoic acid (7.2%), but only a few polyunsaturated fatty acids were found, such as 9,12,15-octadecatrienoic acid (1.9%), 9,12-octadecadienoic acid (Z,Z) (3.4%), and docosahexaenoic acid (0.2%). This is the first occasion that polysaccharides from I. galbana have been demonstrated to exert immunomodulatory properties by the induction of IL-1 within macrophages. 相似文献
963.
Spherical molecular brushes with amphiphilic heteroarms were facilely synthesized by grafting the arms of hydrophobic 2-azidoethyle palmitate and hydrophilic monoazide-terminated poly(ethylene glycol) onto the core of alkyne-modified hyperbranched polyglycerol (HPG) with high molecular weight (M n = 122 kDa) via one-pot parallel click chemistry. The parallel click grafting strategy was demonstrated to be highly efficient (~100%), very fast (~ 2 h) and well controllable to the amphilicity of molecular brushes. Through adjusting the feeding ratio of hydrophobic and hydrophilic arms, a series of brushes with different arm ratios were readily obtained. The resulting miktoarms hyperbranched polymer brushes (HPG-g-C16/PEG350) were characterized by hydrogen-nuclear magnetic resonance (1H NMR), Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) measurements. The spherical molecular brushes showed high molecular weights up to 230 kDa, and thus could be visualized by atomic force microscopy (AFM). AFM and dynamic laser light scattering (DLS) were employed to investigate the self-assembly properties of amphiphilic molecular brushes with closed proportion of hydrophobic and hydrophilic arms. The brushes could self-assemble hierarchically into spherical micelles, and network-like fibre structures, and again spherical micelles by addition of n-hexane into the dichloromethane or chloroform solution of brushes. In addition, this kind of miktoarms polymer brush also showed the ability of dye loading via host-guest encapsulation, which promises the potential application of spherical molecular brushes in supramolecular chemistry. 相似文献
964.
Vinylsilafluorene (VSiF) was successfully synthesized and copolymerized with vinylcarbazole and methyl methacrylate via free radical copolymerization for the first time. The synthesis, photophysical properties, computational modeling studies, and organic light-emitting devices of the VSiF copolymers were presented. The good coordinated photoluminescent (PL) spectra with the absorption of blue light-emitting materials and the high energy band-gap of the VSiF copolymers were observed. Higher triplet band gap (3 E g) to host the blue phosphorescent emitters and better HOMO and LUMO than PVK for electron and hole injection and transportation of the VSiF model compounds were revealed by density functional theory (DFT) calculations. The preliminary device results in applications of these copolymers as host materials for green phosphorescent emitters demonstrate the copolymers of VSiF and vinylcarbazole have comparable device performance of polyvinylcarazole (PVK), suggesting a bright future of VSiF as building blocks for host materials. 相似文献
965.
966.
967.
黄金蝉若虫体蛋白水解液的荧光标记及电喷雾质谱鉴定 总被引:1,自引:0,他引:1
采用2-[2-(7H-二苯并[a,g]咔唑-乙氧基)-乙基]氯甲酸酯(DBCEC-Cl)作为柱前衍生试剂, 于室温下,在硼酸钠缓冲液(pH 9.0)中,金蝉若虫体蛋白水解液中氨基酸的完全衍生化在5 min即可完成.在Hypersil BDS C18色谱柱 (200 mm×4.6 mm, 5 μm) 上, 采用梯度洗脱实现了各衍生物的完全基线分离.最佳荧光检测为λex/λem=300/395 nm.在线串联的ESI/MS正离子质谱数据显示:所有衍生物均给出m/z 338 5,294.5的特征碎片离子峰.荧光条件下的线性回归系数大于0.9992; 检出限为2.6~24 fmol.本方法灵敏、可靠、重现性好.对实际黄金蝉若虫体蛋白水解液中氨基酸的测定,结果满意. 相似文献
968.
Chao Wang Tao LiZhixin Wang Feng FengHailin Wang 《Journal of chromatography. A》2010,1217(15):2254-2261
The stereospecific binding of monoclonal antibody (mAb) 8E11 to anti-benzo(a)pyrene diol epoxide (BPDE)-dG adducts in single nucleoside, long oligonucleotide, and genomic DNA were quantitatively evaluated using noncompetitive and competitive capillary electrophoresis (CE) immunoassays. Two single-stranded TMR-BPDE-90mers containing a single anti-BPDE-dG adduct with defined stereochemistry and a fluorescent label at 5′-end were used as fluorescent probes for competitive CE immunoassay. To quantitatively evaluate the binding affinity through competitive CE immunoassays, a series of equations were derived according to the binding stoichiometry. The binding of mAb 8E11 to trans-(+)-anti-BPDE-dG displays strongest affinity (Kb: 3.57 × 108 M−1) among all four investigated anti-BPDE-dG mononucleoside adducts, and the cis-(−)-anti-BPDE-dG displays lowest affinity (Kb: 1.14 ×107 M−1). The binding of monoclonal antibody (mAb) 8E11 to BPDE-dG adducts in long DNA (90mer) preferentially forms the complex with a stoichiometry of 1:1, and that mAb 8E11 displays a slightly higher affinity with trans-(+)-anti-BPDE-90mers (Kb: 6.36 ± 0.54 × 108 M−1) than trans-(−)-anti-BPDE-90mers (Kb: 4.52 ± 0.52 × 108 M−1). The mAb 8E11 also displays high affinity with BPDE-dG adducts in genomic DNA (Kb: 3.74 × 108 M−1), indicating its promising applications for sensitive immuno-detection of BPDE-DNA adducts in genomic DNA. 相似文献
969.
970.
本文在多类型复发间隔时间数据下,研究了一类广义半参数风险回归模型的参数估计问题,给出了该模型中未知参数和非参数函数的一种估计方法,并证明了估计量的相合性和渐近正态性.最后利用数值模拟来评估估计量在有限样本下的表现. 相似文献