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991.
设计合成了一系列基于羟基和氨基的酰腙类受体分子.利用紫外-可见吸收光谱及1HNMR考察了其与F-,Cl-,Br-,I-,CH3COO-,H2PO4?,HSO4?,ClO?4等阴离子的作用.结果表明,该类受体分子在DMSO溶液中能较好地比色识别F-,CH3COO-,H2PO4?,其中受体2在含水介质中[V(DMSO)∶V(H2O)=7∶3]能选择性比色识别CH3COO-.1HNMR滴定实验研究了受体分子与阴离子之间的作用,结果表明受体分子与阴离子之间以氢键作用方式相结合. 相似文献
992.
In this paper, we develop a concise approach to (+)‐benzene diol epoxide and (+)‐conduramine A‐1 based upon the utilization of the C2‐symmetric L‐tartaric acid as a chiral building block. 相似文献
993.
Chang‐Ling Duan Yu‐Juan Li Peng Li Yong Jiang Jian‐Xun Liu Peng‐Fei Tu 《Helvetica chimica acta》2010,93(2):227-232
Three new steroidal saponins, (25R)‐ruscogenin‐3‐yl α‐L ‐rhamnopyranosyl‐(1→2)‐[β‐D ‐xylopyranosyl‐(1→4)]‐β‐D ‐glucopyranoside ( 1 ), diosgenin‐3‐yl 2‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐[β‐D ‐xylopyranosyl‐(1→4)]‐β‐D ‐glucopyranoside ( 2 ), and pennogenin‐3‐yl 2‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐[β‐D ‐xylopyranosyl‐(1→4)]‐β‐D ‐glucopyranoside ( 3 ) were isolated from the fibrous roots of Ophiopogon japonicus (Thunb .) Ker‐Gawl . Their structures were determined by spectroscopic methods including IR, HR‐ESI‐MS, and 1D‐ and 2D‐NMR. All of these three steroidal saponins exhibited weak cytotoxicities against Hela and Hep2 cell lines. 相似文献
994.
Lawrence W. Potts Dwight R. Stoll Xiaoping Li Peter W. Carr 《Journal of chromatography. A》2010,1217(36):5700-5709
Comprehensive two-dimensional liquid chromatography (2DLC) offers a number of practical advantages over optimized one-dimensional LC in peak capacity and thus in resolving power. The traditional “product rule” for overall peak capacity for a 2DLC system significantly overestimates peak capacity because it neglects under-sampling of the first dimension separation. Here we expand on previous work by more closely examining the effects of the first dimension peak capacity and gradient time, and the second dimension cycle times on the overall peak capacity of the 2DLC system. We also examine the effects of re-equilibration time on under-sampling as measured by the under-sampling factor and the influence of molecular type (peptide vs. small molecule) on peak capacity. We show that in fast 2D separations (less than 1 h), the second dimension is more important than the first dimension in determining overall peak capacity and conclude that extreme measures to enhance the first dimension peak capacity are usually unwarranted. We also examine the influence of sample types (small molecules vs. peptides) on second dimension peak capacity and peak capacity production rates, and how the sample type influences optimum second dimension gradient and re-equilibration times. 相似文献
995.
Nataša Novak Tušar Dr. Alenka Ristić Dr. Gregor Mali Dr. Matjaž Mazaj Dr. Iztok Arčon Prof. Denis Arčon Prof. Venčeslav Kaučič Prof. Nataša Zabukovec Logar Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5783-5793
A two‐step synthesis of a novel mesostructured silicate, KIL‐2, and its manganese‐containing analogue, Mn/KIL‐2, has been developed. KIL‐2 possesses interparticle mesopores with pore dimensions between 5 and 60 nm and a surface area of 448 m2. The mesopores are formed by the aggregation of silica nanoparticles, which creates a network with interparticle voids. The particle size and the pore diameters depend on the temperature of the ageing step (first step) and on the solvothermal treatment in ethanol (second step), respectively. Mn/KIL‐2 contains octahedrally coordinated Mn3+ (80 %) and tetrahedrally coordinated Mn2+ (20 %) ions. Mn3+ ions are present in the extra‐framework MnOx nanoparticles with typical dimensions of 2 nm, which are homogeneously distributed throughout the material. Mn2+ ions occur as isolated manganese framework sites. The material is also able to retain its structure characteristics after the hydrothermal treatment in boiling water. Because of its non‐toxic nature and cost‐effective synthesis, Mn/KIL‐2 thus exhibits properties that are needed for an environment‐friendly catalyst. 相似文献
996.
Feng Qiu Chunlai Tu Yan Chen Yunfeng Shi Liang Song Ruibing Wang Prof. Xinyuan Zhu Prof. Bangshang Zhu Prof. Deyue Yan Prof. Tao Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(42):12710-12717
A self‐assembly approach to tuning the optical properties of a star copolymer is reported herein. The star copolymer HCP‐star‐PEG with a hyperbranched conjugated polymer (HCP) core and many linear poly(ethylene glycol) (PEG) arms has been prepared successfully. The HCP core was synthesized by Wittig coupling of N‐(n‐hexyl)‐3,6‐diformylcarbazole and 1,3,5‐bis[(triphenylphosphonio)methyl]benzene tribromide. Subsequently, the linear PEG arms were grafted onto the HCP core by acylhydrazone connection. It was found that the optical properties of HCP‐star‐PEG in chloroform solution changed on addition of acid. Both 1H NMR and UV/Vis spectroscopic investigations confirmed that the variation of the optical properties was related to the complexation of the acid and the imine bond in the acylhydrazone group. HCP‐star‐PEG self‐assembled into core–shell micelles in the mixed solvent of chloroform and acetonitrile, which affected the protonation of the imine bond. Therefore the optical properties of HCP‐star‐PEG can be readily controlled by self‐assembly. 相似文献
997.
Jingjing Yu Jiaxing Tu Faqiong Zhao Baizhao Zeng 《Journal of Solid State Electrochemistry》2010,14(9):1595-1600
A magnetic mesoporous carbon material (i.e., mesoporous iron oxide/C, mesoFe/C) is synthesized for protein immobilization,
using glucose oxidase (GOx) as model. Transmission electron microscopy images show that mesoFe/C has highly ordered porous
structure with uniform pore size, and iron oxide nanoparticles are dispersed along the wall of carbon. After adsorption of
GOx, the GOx-mesoFe/C composite is separated with magnet. The immobilized GOx remains its natural structure according to the
reflection–absorption infrared spectra. When the GOx-mesoFe/C composite is coated on a Pt electrode surface, the GOx gives
a couple of quasireversible voltammetric peaks at −0.5 V (vs. saturated calomel electrode) due to the redox of FAD/FADH2. The electron-transfer rate constant (k
s) is ca. 0.49 s−1. The modified electrode presents remarkably amperometric response to glucose at 0.6 V. The response time (t
95%) is less than 6 s; the response current is linear to glucose concentration in the range of 0.2–10 mM with a sensitivity of
27 μA mM−1 cm−2. The detection limit is 0.08 mM (S/N = 3). The apparent Michaelis–Menten constant (K
mapp) of the enzyme reaction is ca. 6.6 mM, indicating that the GOx immobilized with mesoFe/C has high affinity to the substrate. 相似文献
998.
收集了6种产自肝癌高发区——江苏省启东市的红豆和6种产自国内其他地区的红豆,经过微波消解或干灰化法处理后,采用电感耦合等离子体发射光谱法(ICP-OES)、原子吸收光谱法(AAS)和原子荧光光谱法(AFS)测定了其中A l、B、Ba、Ca、Cd、Co、Cr、Cu、Fe、Hg、K、Mg、Mn、Mo、Na、N i、P、Pb、Rb、S、Se、Sr和Zn共23种矿质元素的含量,并用生物标准参考物质黄豆评价了分析方法的准确度。结果表明,红豆中人体必需宏量、微量元素含量极为丰富,而传统意义上的有害元素Pb、Cd、Hg含量均较低;与国内其他产地的红豆相比,江苏省启东市产红豆中B、Mg含量显著偏高(P0.05),而大多数矿质元素含量两相比较并不存在显著性差异。产自江苏省启东市的部分红豆样品和产自江苏省海门市的红豆样品中Cd含量极低,预示着自然生态环境中有效态Cd缺乏可能与肝癌的高发病率和高死亡率存在一定程度的相关性。 相似文献
999.
Mihaela Dragusanu Brîndusa-Alina Petre Stefan Slamnoiu Camelia Vlad Tingting Tu Michael Przybylski 《Journal of the American Society for Mass Spectrometry》2010,21(10):1643-1648
We describe here an on-line combination of a surface acoustic wave (SAW) biosensor with electrospray ionization mass spectrometry
(SAW-ESI-MS) that enables the direct detection, identification, and quantification of affinity-bound ligands from a protein-ligand
complex on a biosensor chip. A trapping column was used between the SAW-biosensor and the electrospray mass spectrometer equipped
with a micro-guard column, which provides simultaneous sample concentration and desalting for the mass spectrometric analysis
of the dissociated ligand. First applications of the on-line SAW-ESI-MS combination include (1), differentiation of β-amyloid
(Aβ) epitope peptides bound to anti-Aβ antibodies; (2), the identification of immobilized Substance P peptide-calmodulin complex;
(3), identification and quantification of the interaction of 3-nitrotyrosine-modified peptides with nitrotyrosine-specific
antibodies; and (4), identification of immobilized anti-α-synuclein-human α-synuclein complex. Quantitative determinations
of protein-ligand complexes by SAW yielded dissociation constants (KD) from micro-to low nanomolar sample concentrations. The on-line bioaffinity-ESI-MS combination presented here is expected
to enable broad bioanalytical application to the simultaneous, label-free determination and quantification of biopolymer-ligand
interactions, as diverse as antigen-antibody and lectin-carbohydrate complexes. 相似文献
1000.
Tingting Tu Mihaela Drăgu§anu Brînduşa-Alina Petre Don L. Rempel Michael Przybylski Michael L. Gross 《Journal of the American Society for Mass Spectrometry》2010,21(10):1660-1667
A new methodology using hydrogen/deuterium amide exchange (HDX) to determine the binding affinity of protein-peptide interactions
is reported. The method, based on our previously established approach, protein ligand interaction by mass spectrometry, titration,
and H/D exchange (PLIMSTEX) [J. Am. Chem. Soc.
2003, 125, 5252–5253], makes use of a dilution strategy (dPLIMSTEX) for HDX, using the mass of the peptide ligand as readout. We employed
dPLIMSTEX to study the interaction of calcium-saturated calmodulin with the opioid peptide β-endorphin as a model system;
the affinity results are in good agreement with those from traditional PLIMSTEX and with literature values obtained by using
other methods. We show that the dPLIMSTEX method is feasible to quantify an antigen-antibody interaction involving a 3-nitrotyrosine
modified peptide in complex with a monoclonal anti-nitrotyrosine antibody. A dissociation constant in the low nanomolar range
was determined, and a binding stoichiometry of antibody/peptide of 1:2 was confirmed. In addition, we determined that the
epitope in the binding interface contains a minimum of five amino acids. The dPLIMSTEX approach is a sensitive and powerful
tool for the quantitative determination of peptide affinities with antibodies, complementary to conventional immuno-analytical
techniques. 相似文献