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991.
Cheng‐Xiong Liu Zhi‐yong Guo Yan‐Hong Xue Hong‐Yan Zhang Hong‐Qi Zhang Kun Zou Nian‐Yu Huang 《Magnetic resonance in chemistry : MRC》2012,50(4):320-324
Three new steroidal compounds with polyhydroxy groups, tupisteroide A–C (1–3), were obtained from the roots of Tupistra chinensis, together with one known compound (4) that was isolated from this plant for the first time. The structures of tupisteroide A–C were determined on the basis of one‐ and two‐dimensional NMR spectroscopy, including 1H–1H Correlation Spectroscopy, Heteronuclear Multiple Bond Correlation, and Heteronuclear Single Quantum Coherence experiments. The isolated compounds were evaluated for their cytotoxic activities against A549, HepG2, and CaSki cancer cell lines in vitro. Among them, compounds 1, 2, and 4 did not show significant inhibitory activity, but compound 3 showed cytotoxicity against A549 cancer cell lines with IC50 values of 25.0 μM. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
992.
Ly Dieu Ha Poul Erik Hansen Fritz Duus Hung Dinh Pham Lien‐Hoa D. Nguyen 《Magnetic resonance in chemistry : MRC》2012,50(3):242-245
Four new prenylated depsidones, oliveridepsidones A–D, were isolated from the bark of Garcinia oliveri collected in Vietnam. Their structures were elucidated using mainly NMR techniques (1H and 13C NMR, HMQC, HMBC and NOE experiments). Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
993.
Xiao‐Jie Liu Zhen‐Yu Li Zhong‐Feng Li Xiao‐Xia Gao Yu‐Zhi Zhou Hai‐Feng Sun Li‐Zeng Zhang Xiao‐Qing Guo Guan‐Hua Du Xue‐Mei Qin 《Magnetic resonance in chemistry : MRC》2012,50(3):187-192
Chronic unpredictable mild stress (CUMS) is a well‐validated model of depression. In this study, a urinary metabonomics method based on the NMR spectrometry was used to study the metabolic perturbation in CUMS‐induced rat depression model. With pattern recognition analysis, a clear separation of CUMS rats and healthy controls was achieved, and nine endogenous metabolites contributing to the separation were identified. CUMS‐treated rats were characterized by the increase of glycine, pyruvate, glutamine, and asparagines, as well as the decrease of 2‐oxoglutarate, dimethylglycine, citrate, succinate, and acetate. The urinary biochemical changes related to the metabolic disturbance in CUMS induced depression, and the possible correlations with live qi stagnation in traditional Chinese medicine are discussed. The work shows that CUMS is a reliable model for studying depression, and the noninvasive urinary metabolomic method is a valuable tool to investigate the biochemical pertubations in depression as an early diagnostic means. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
994.
Dionisia Sanz Rosa M. Claramunt Ibon Alkorta Goar Sánchez‐Sanz José Elguero 《Magnetic resonance in chemistry : MRC》2012,50(3):246-255
The structure of glibenclamide, 5‐chloro‐N‐(2‐{4‐[(cyclohexylamino)carbonyl] aminosulfonyl}phenyl) ethyl)‐2‐methoxybenzamide, an important antidiabetic drug, has been studied both in solution and in the solid state by a combination of NMR spectroscopy and theoretical calculations. The possibility that glibenclamide suffers a tautomerization under melting to afford a desmotrope was rejected. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
Mouna Hnaien Sergei Dzyadevych Florence Lagarde Nicole Jaffrezic‐Renault 《Electroanalysis》2012,24(6):1441-1445
In this work, a fast, sensitive and miniaturised conductometric sensor based on interdigitated electrodes, working in differential mode, was developed for the determination of cationic surfactants. The membrane was composed of a polymer (PVC), a plasticizer (dinonylphtalate (DNP)) and a carrier (sodium tetraphenylborate (NaBΦ4)). The sensor response was linear from at least 10?9 M to 10?2 M for dodecyltrimethylammonium (DTA+). No significant loss of sensor response was observed after 8 weeks. The sensor exhibited a lower sensitivity and a narrower dynamic range for tetrabutylammonium, decyltrimethylammonium and cetyltrimethylammonium cationic surfactants. A ten times lower sensitivity was observed for laurylsulfate anionic surfactant, (LS?). 相似文献
996.
Hui Li Peng Tang Yan Zhao Shi‐Xia Liu Yves Aeschi Lijun Deng Jörg Braun Bin Zhao Yunqi Liu Songting Tan Wolfgang Meier Silvio Decurtins 《Journal of polymer science. Part A, Polymer chemistry》2012,50(14):2935-2943
Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo[1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of ?5.38 and ?5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10?8 cm2 V?1 s?1 in PBDF to 1.0 × 10?5 cm2 V?1 s?1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm?2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
997.
Georgia‐Paraskevi Nikoleli Muhammad Q. Israr Nikolaos Tzamtzis Dimitrios P. Nikolelis Magnus Willander Nikolas Psaroudakis 《Electroanalysis》2012,24(6):1285-1295
The present article describes a miniaturized potentiometric urea lipid film based biosensor on graphene nanosheets. Structural characterization of graphene nanosheets for miniaturization of potentiometric urea lipid film based biosensors have been studied through atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. UV‐Vis and Fourrier transform IR (FTIR) spectroscopy have been utilized to study the pre‐ and postconjugated surfaces of graphene nanosheets. The presented potentiometric urea biosensor exhibits good reproducibility, reusability, selectivity, rapid response times (~4 s), long shelf life and high sensitivity of ca. 70 mV/decade over the urea logarithmic concentration range from 1×10?6 M to 1×10?3 M. 相似文献
998.
Manoj K. Kolel‐Veetil Kenan P. Fears Syed B. Qadri Christopher A. Klug Teddy M. Keller 《Journal of polymer science. Part A, Polymer chemistry》2012,50(15):3158-3170
A semicrystalline inorganic–organic hybrid crosslinked network containing polyhedral oligomeric silsesquioxane (POSS) cores was constructed by the unusual hydrosilylation of the terminal vinyl groups of an internal acetylene‐containing silane linker by a POSS monomer. Products from the thermal treatments of this network in either argon or air at 250, 550, and 1000 °C, respectively, were characterized by Fourier transform infrared, Solid‐state 13C and 29Si magic angle spinning NMR, X‐ray diffraction and XPS analyses. The highly symmetrically functionalized POSS silica clusters, in the fluorite silica phase, in the network were found to remain unchanged on thermal treatment possibly due to the shielding of the silica core by the functionalities and a cancellation of thermal stresses on the silica core. Stabilization of the metastable α‐cristobalite phase, which is typically formed on cooling by a β‐ to α‐transition of the β‐cristobalite phase formed above 1400 °C, was observed in the amorphous regions in the network sample treated only to 1000 °C in air. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
999.
Christoph Herfurth Dominik Voll Jens Buller Jan Weiss Christopher Barner‐Kowollik André Laschewsky 《Journal of polymer science. Part A, Polymer chemistry》2012,50(1):108-118
We report on the controlled free radical homopolymerization of 1‐ferrocenylethyl acrylate as well as of three new ferrocene bearing monomers, namely 4‐ferrocenylbutyl acrylate, 2‐ferrocenylamido‐2‐methylpropyl acrylate, and 4‐ferrocenylbutyl methacrylate, by the RAFT technique. For comparison, the latter monomer was polymerized using ATRP, too. The ferrocene containing monomers were found to be less reactive than their analogues free of ferrocene. The reasons for the low polymerizability are not entirely clear. As the addition of free ferrocene to the reaction mixture did not notably affect the polymerizations, sterical hindrance by the bulky ferrocene moiety fixed on the monomers seems to be the most probable explanation. Molar masses found for 1‐ferrocenylethyl acrylate did not exceed 10,000 g mol?1, while for 4‐ferrocenylbutyl (meth)acrylate molar masses of 15,000 g mol?1 could be obtained. With PDIs as low as 1.3 in RAFT polymerization of the monomers, good control over the polymerization was achieved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
1000.
Prof. Dr. José Luis García Ruano Dr. José Alemán Leyre Marzo Dr. Cuauhtémoc Alvarado Dr. Mariola Tortosa Dr. Sergio Díaz‐Tendero Dr. Alberto Fraile 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8414-8422
We describe the unexpected behavior of the arylsulfonylacetylenes, which suffer an “anti‐Michael” addition of organolithiums producing their alkynylation under very mild conditions. The broad scope, excellent yields, and simplicity of the experimental procedure are the main features of this methodology. A rational explanation of all these results can be achieved by theoretical calculations, which suggest that the association of the organolithiums to the electrophile is a previous step of their intramolecular attack and is responsible for the unexpected “anti‐Michael” reactions observed for substituted sulfonylacetylenes. 相似文献