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991.
Two new triterpenoids, schisanbilactones A and B ( 1 and 2 , resp.), and a new natural product, 1‐chloro‐3‐phenylhex‐5‐en‐3‐ol ( 3 ), as well as a known triterpenoid, kadsulactone A ( 4 ), were isolated from the stems of Schisandra bicolor. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D‐NMR techniques. 相似文献
992.
Małgorzata Jóźwiak 《The Journal of chemical thermodynamics》2009,41(4):522-524
The enthalpies of solution of cyclic ethers: 1,4-dioxane, 12-crown-4 and 18-crown-6 in {(1 ? x)AN + xH2O} have been measured over the whole mole fraction range at T = 298.15 K. Based on the results obtained, the effects of base–acid properties of mixed solvent and the number of –CH2CH2– groups in cyclic ethers molecules on the solution enthalpy of cyclic ethers in {(1 ? x)AN + xH2O} have been analyzed. 相似文献
993.
Fang Ma 《European Polymer Journal》2009,45(7):2131-4920
The well-defined phenylazo indazole-terminated polystyrene (PS) was successfully prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene (St) mediated by a novel chain transfer agent (CTA) bearing phenylazo indazole moieties in the Z group, benzyl-5-(4-(dimethylamino)phenylazo) indazole-1-carbodithioate (BPCD). The fluorescence emission of BPCD and the phenylazo indazole-terminated PS in chloroform (CHCl3) before and after the 365 nm ultraviolet irradiation was investigated. Interestingly, the fluorescence intensities of BPCD and the phenylazo indazole-terminated PS in CHCl3 were both sensitive to the 365 nm ultraviolet irradiation. The fluorescence intensities of these solutions increased with the irradiation time and reached maximum at 110 min. The light-driven fluorescence enhancement of BPCD and the phenylazo indazole-terminated PS were both attributed to the formation of spherical aggregate originated from the trans-cis isomerization of azobenzene moieties in BPCD and PS chain, which was confirmed by transmission electron microscopy (TEM), 1H NMR, UV and dynamic light scattering (DLS) spectra. 相似文献
994.
Bin Ma Chun‐Fu Wu Jing‐Yu Yang Rui Wang Yoshihiro Kano Dan Yuan 《Helvetica chimica acta》2009,92(8):1575-1585
Three new alkaloids, 2′‐O‐β‐D ‐glucopyranosyl‐11‐hydroxyvincoside lactam ( 1 ), 22‐O‐demethyl‐22‐O‐β‐D ‐glucopyranosylisocorynoxeine ( 2 ), and (4S)‐corynoxeine N‐oxide ( 3 ) were isolated from the leaves of Uncaria rhynchophylla, together with four known tetracyclic oxindole or indole alkaloids, isocorynoxeine N‐oxide ( 4 ), rhynchophylline N‐oxide ( 5 ), isorhynchophylline N‐oxide ( 6 ), and dihydrocorynantheine ( 7 ), and an indole alkaloid glycoside, strictosidine ( 8 ). The structures of 1 – 3 were elucidated by spectroscopic methods including UV, IR, ESI‐TOF‐MS, 1D‐ and 2D‐NMR, as well as CD experiments. The activity assay showed that 8 (IC50=8.3 μM ) exhibited potent inhibitory activity on lipopolysaccharide(LPS)‐induced nitrogen monoxide (NO) release in N9 microglia cells. However, only weak inhibitory activities were observed for 1 – 7 (IC50>100 μM for 1 – 6 or >30 μM for 7 ). 相似文献
995.
Poly(N,N-diethylacrylamide) with a terminal hydroxyl end group (PDEA-OH) was synthesized by radical telomerization of N,N-diethylacrylamide (DEA) monomer using 2-hydroxyethanethiol as a chain transfer agent. Macromonomer of thermo-sensitive PDEA was synthesized by condensation reaction of PDEA-OH with acryloyl chloride. The macromonomer was characterized by FTIR and 1H NMR, and the molecular weight was determined by GPC. Thermo- and pH-sensitive comb-type grafted poly(N,N-diethylacrylamide-co-acrylic acid) (PDEA-co-AA) hydrogels (GHs) were successfully prepared by grafting PDEA chains with freely mobile ends onto the backbone of a cross-linked (PDEA-co-AA) network. The results showed that the deswelling behavior of the hydrogels was dependent on the test temperature. At 45 °C (beneath the VPTT of the hydrogels), both the normal-type hydrogels (NHs) and comb-type grafted P(DEA-co-AA) hydrogels had lower deswelling rates. While at 60 °C (far beyond the VPTT of the hydrogels), the deswelling rates of the GHs were faster than that of the NHs. Furthermore, pulsatile stimuli-responsive studies indicated that the GHs had excellent thermo-reversibility and were superior to the NHs in the magnitude of their swelling ratios to temperature changes. However, the reversibility to pH changes was poor for both the NHs and the GHs. 相似文献
996.
Xiaoli Ma Le Xie Lifang Liu Qiuling Tang Zhuqing Wan Yuqing Li 《Chromatographia》2009,69(5-6):437-443
Chinese clematis is a Chinese medicine with anti-inflammatory and anti-rheumatoid properties. Studies showed the triterpenoid saponins of this herb represent the major active components with therapeutic activities for the treatment of inflammatory diseases. The LC–ELSD method was developed to quantitatively analyze seven major triterpenoid saponins in 22 samples from different habitats. The linearity, sensitivity, precision, and accuracy were investigated. It showed the great variation of the contents of each saponin. We concluded clematichinenoside AR is the major saponin in all the samples. This method can be used to effectively evaluate and monitor the quality of Chinese clematis in clinical use. 相似文献
997.
High-performance liquid chromatography with tandem mass spectrometry has been used for rapid, specific, and sensitive analysis of busulfan in human plasma. Busulfan-d8 was used as internal standard. Analysis was performed on a C18 column (50 mm × 2.1 mm, 3.5-µm particles) with water–methanol 80:20 (v/v) as mobile phase at a flow-rate of 0.30 mL min?1. Detection was by tandem triple–quadrupole mass spectrometry with turbo ion-spray ionization. Linear calibration plots were obtained over the concentration range 1.096–1,096 ng mL?1. The assay is ideally suited to monitoring of busulfan and determination of its pharmacokinetic data. 相似文献
998.
Małgorzata Olejnik Teresa Szprengier-JuszkiewiczPiotr Jedziniak 《Journal of chromatography. A》2009,1216(46):8141-8148
The confirmatory LC-MS/MS method for the determination of residues for twelve coccidiostats including ionophore antibiotics (lasalocid, maduramycin, monensin, narasin, salinomycin, semduramycin) and chemical coccidiostats (clazuril, decoquinate, diclazuril, halofuginone, nicarbazin and robenidine) in poultry liver has been developed. The sample preparation was based on extraction with acetonitrile, defatting with Alumina columns and clean-up on Oasis HLB spe. The separation of analytes was performed on PhenylHexyl column with a gradient of acetonitrile, methanol and the ammonium formate pH 4.0. For all analytes, at least 2 diagnostic fragmentation ions were monitored. The validation, performed according to the CD 2002/657/EC, proved the suitability of the method for the confirmatory analysis of the coccidiostats. For lasalocid, however, low reproducibility was observed and the proper quantification could not be performed with this method. 相似文献
999.
Ma del Carmen Fernández-Fernández Alejandro Macías Laura Valencia 《Journal of organometallic chemistry》2009,694(22):3608-3613
The coordination capability of the new tetrapyridyl pendant-armed azamacrocyclic ligand L, towards Co(II), Ni(II), Cu(II) and Cd(II) ions was studied. The ligand and the complexes were characterized by microanalysis, LSI mass spectrometry, IR, UV-Vis and NMR spectroscopy, magnetic studies and conductivity measurements. Crystal structures of [Co2L(CH3CN)2](ClO4)4·2CH3CN and [Cd2L(NO3)2](NO3)2·2H2O complexes have been determined. The X-ray studies show the presence of dinuclear endomacrocyclic complexes with the metal ion in a similar distorted octahedral environment, coordinated by one pyridyl bridgehead group, two amine nitrogen atoms and two pyridyl pendant-arms. The sixth coordination position around the metal ion is completed by one acetonitrile molecule in [Co2L(CH3CN)2](ClO4)4·2CH3CN and by one monodentate nitrate anion in [Cd2L(NO3)2](NO3)2·2H2O. Different sort of intramolecular non-classical hydrogen bonds were found in the crystal lattice of both structures. 相似文献
1000.
Hao-Xiang Zhong Ying-Li Ma Xue-Tai Chen Zi-Ling Xue 《Journal of solid state chemistry》2009,182(7):1679-2917
A simple hydrothermal reaction between Ba(NO3)2 and K2SiF6 results in the formation of 1D rod-like BaSiF6. The BaSiF6 rods can act as efficient precursors for production of tubular SiO2 by hydrothermal reaction in alkaline solutions. Powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM), and field emission scanning electron microscopy (FESEM) were used to characterize the phase and morphology of the final product. The experiments indicated the amount of NaOH, reaction temperature, and reaction time played important roles in the transformation process. A possible growth mechanism of tubular silica was proposed. 相似文献