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排序方式: 共有1319条查询结果,搜索用时 312 毫秒
921.
Kondo A Noguchi H Kajiro H Carlucci L Mercandelli P Proserpio DM Tanaka H Kaneko K Kanoh H 《The journal of physical chemistry. B》2006,110(51):25565-25567
One-dimensional metal-organic compounds with cis, trans symmetry-controlled counter anions were synthesized (cis compound {[Cu(azpy)(H2O)2(OTs)2]*2H2O*(acetone)} (1) and trans compound {[Cu(H2O)4Cu(azpy)2(OTs)2(H2O)2]*2(OTs)*2H2O*2EtOH} (2)). Only 2, having trans conformation, exhibited a complete structure-restoration effect with a mechanism involving layering of molecular "bricks" of water and solvent molecules. 相似文献
922.
Ingrosso C Petrella A Cosma P Curri ML Striccoli M Agostiano A 《The journal of physical chemistry. B》2006,110(48):24424-24432
The optical properties of zinc phthalocyanine (ZnIIPc) and magnesium phthalocyanine (MgIIPc) in DMSO and DMF solutions have been extensively investigated, and the photoelectrochemical behaviors of layer-by-layer hybrid junctions formed of the two metallo(II) phthalocyanines (MIIPcs) and wide-band-gap colloidal semiconductors, namely, ZnO and TiO2 nanocrystals (NCs), have been probed. Different experimental conditions, such as the Pc center metal ion, dye concentration, and solvent identity, were investigated in order to elucidate their effects on the photoelectrochemical performances of the prepared heterojunctions. Finally, thermal treatment of either dye and NC films and control of the NC shape and surface chemistry were also studied and, interestingly, were found to be critical in affecting the performance of photochemical sensitization processes, occurring at the dye/oxide and oxide/solution interfaces. 相似文献
923.
Gambaro V Casagni E Dell'Acqua L Valenti M Visconti GL 《Journal of separation science》2006,29(9):1294-1297
Biogenic polyamines, such as spermidine (SPD, NH2-(CH2)4-NH-(CH2)3-NH2), are ubiquitous polycationic molecules which play a definitive role in many biological processes such as nucleic acid metabolism, protein synthesis, and cell growth. SPD is commonly used as an ingredient in hair lotions, because it seems to promote hair growth. This work describes a capillary GC method for quantitative determination of SPD in hair lotions using 1,6-diaminohexane as internal standard, a methyl silicone capillary column, and a flame ionisation detector. Aliquots of hair lotion were treated with an alkaline aqueous solution and internal standard was added. The emulsion was extracted with diethyl ether containing ethyl chloroformate. Ether extracts, evaporated to dryness and reconstituted in ethyl acetate, were analysed by capillary GC with flame ionisation detection. Validation took into account the specificity, linearity, precision, and accuracy of the analytical method: these parameters were valid for the quantitative determination of SPD in hair lotion. 相似文献
924.
J. Pablo Lamas Lucia Sanchez-PradoCarmen Garcia-Jares Maria Llompart 《Journal of chromatography. A》2009,1216(30):5755-5758
A fast, simple, low cost, and high throughput method has been developed for the determination of dimethyl fumarate (DMF) in desiccant and anti-mould agents employed for protecting clothes, footwear and accessories from humidity and mould. The procedure is based on ultrasound-assisted extraction followed by GC-μECD analysis. The method was conveniently optimized, and the analyte was efficiently extracted from the samples in only 5 min using such a low volume of solvent (ethyl acetate) as 1 mL. Simultaneous extractions could be carried out in also 5 min without loosing efficiency. The method has been validated showing good linearity and selectivity. Precision was satisfactory with RSD of 4–5%. Recovery was evaluated in two real samples at different DMF concentration levels and was >90% in all cases. Limit of detection and quantification were at the ng g−1 level. The proposed procedure was applied to the determination of DMF in several desiccant and anti-mould samples. Although most of them were labelled as “silica gel” all the samples tested with the exception of three presented important amounts of DMF, many of them at the high μg g−1 level. The presence and the high concentrations of this allergenic fungicide in desiccant and anti-mould sachets employed in many consumer products, such as clothes and footwear, should be a matter of concern. 相似文献
925.
An efficient stereoselective preparation of the two enantiomerically pure diasteroisomers of γ-benzyloxy-S-glutamic acid was performed using trans-4-hydroxy-l-proline as a source of chirality, while the erythro and threo isomers of β-benzyloxy-S-glutamic acid were prepared starting from (R)-Garner's aldehyde. All new derivatives were tested for their inhibitory activity against excitatory amino acid transporters in a rat synaptosomal preparation and their IC50 values were compared to that of TBOA, a one carbon lower homologue commonly used as the reference blocker of glutamate transporters. 相似文献
926.
Easily accessible cycloalkenyl-1-diazenes and β-dicarbonyl compounds are converted in one-pot into previously unknown functionalized fused cycloalkenyliden-pyrroles of different sizes. The domino reaction proceeds through a base-catalyzed conjugate addition/cyclization/elimination sequence. 相似文献
927.
A convenient and simple approach for the recyclable catalytic synthesis of substituted quinolines is presented. The method is based on CuCl2-catalyzed heterocyclization of readily available 1-(2-aminoaryl)-2-yn-1-ols in BmimBF4 as the solvent at 100 °C for 15-24 h. The solvent-catalyst system could be successfully recycled up to six times without significant loss of activity. 相似文献
928.
Ján Halgaš Viera Kolenová Zuzana Števíková Lucia Perašínová Jozef Kožíšek 《Chemical Papers》2009,63(3):323-328
Although thienopyridines attract attention because of their biological activities, they have not been used as ligands in coordination
compounds. Thieno[2,3-b]pyridine was prepared by known procedures; by reduction of 2-nitrothiophene, and reaction of the resulting 2-thienyl ammonium
salt with malondialdehyde tetramethylacetal in the presence of zinc chloride. The same procedure was used for the preparation
of a new derivative, 2-methylthieno[2,3-b]pyridine, starting from 2-methyl-5-nitrothiophene. The thienopyridines were used in the synthesis of coordination compounds.
Chlorides, isothiocyanates, acetates, and chloroacetates of copper(II), nickel(II), or cobalt(II) were used as starting salts.
The prepared complexes were characterized by elemental analysis and FT IR. Structures of the four complexes were determined
by single-crystal X-ray diffraction analysis.
Presented at the 1st International Conference “Applied Natural Sciences” on the occasion of the 10th anniversary of the University
of Ss. Cyril and Methodius, Trnava, 7–9 November 2007. 相似文献
929.
In a reflexive Banach space we consider a family of functionals that may admit unbounded Palais-Smale sequences. Under some
structural conditions we provide a suitable Deformation Lemma that is obtained by modifying the classical pseudo-gradient
flow. This leads to a variant of the minimax principle in the Lusternik-Schnirelman Theory. 相似文献
930.
Frank C. De Lucia 《Journal of Molecular Spectroscopy》2010,261(1):1-1015
The submillimeter spectral region has undergone an explosive growth in the last decade, not only in its impact on the larger scientific and technological world, but also in the high resolution laboratory spectroscopy that makes much of this success possible. Major astronomical and atmospheric instruments are the most visible evidence, but the impact is much broader. This breadth lays the foundation for the impact of submillimeter spectroscopy to extend beyond the scientific community. In this paper we consider the scientific and technical foundations of submillimeter spectroscopy and show how the underlying physics has made possible current successes and shows the path forward to even greater opportunities. 相似文献