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排序方式: 共有235条查询结果,搜索用时 31 毫秒
131.
Successful deposition of Pd nanoparticles is described using MOF‐199 as a support. Various characterization techniques including FTIR, XRD, SEM, BET‐BJH, TG‐DTA, and NH3‐TPD were used to verify the efficiency of catalysts. Pd/MOF‐199 is utilized as a catalyst for Suzukie Miyaura reactions with reasonable to excellent reaction yields under reflux conditions in H2O: ethanol solvent. 相似文献
132.
A simple and versatile procedure for the combinatorial synthesis of (Z)-dialkyl-5-(alkylimino)-5Hspiro[ furan-2,11'-indeno[1,2-b]quinoxaline]-3,4-dicarboxylates via the catalyst-free one-pot fourcomponent reaction of ninhydrin, benzene-1,2-diamines, dialkyl acetylenedicarboxylates and isocyanides is described. 相似文献
133.
The present study reports the synthesis of Co(II), Ni(II), Mn(II), Cu(II), and Zn(II) complexes with a new macrocyclic ligand (L2)- 1,2,8,9,11,14-hexaazacyclopentadeca-12,13-dioxo-10,15-dithione-2,7-diene. The macrocycle was derived from thiosemicabazone (L1) and diethyloxalate that were prepared by the reaction of thiosemicarbazide and glutaraldehyde in the ratio of 2:1. The synthesized complexes and ligands were characterized by elemental analysis and molar conductance, magnetic susceptibility, 1HNMR, IR, electronic, and thermogravimetric analyses. The molar conductance values confirmed that the Ni(II), Cu(II), Zn(II), Mn(II) and Co(II) complexes were 1:2 electrolytes. On the basis of electronic spectral studies and molar conductance measurements, the authors proposed an octahedral structure for Ni(II), Mn(II), and Co(II) complexes, tetrahedral geometry for Zn(II) complex, and square planar geometry for Cu(II) complex. The thermal behavior of the compounds was studied by TGA in a nitrogen atmosphere up to 750°C at the rate of 20°C/min. The TGA results revealed that the complexes had higher thermal stability than the macrocycle. All the synthesized compounds were screened against 4 bacteria (i.e., Streptococcus aureus, Escherichia coli, Bacillus subtillis, Salmonella typhimurium) and 2 fungi (i.e., Fusarium oryzae, Candida albicans). The results showed that the metal complexes inhibited the growth of bacteria to a greater extent as compared to the ligand. 相似文献
134.
Nahid Mashkouri Najafi Hamed Tavakoli Yaser Abdollahzadeh Reza Alizadeh 《Analytica chimica acta》2012
Herein, ultrasound-assisted emulsification microextraction (USAEME) and dispersive liquid–liquid microextraction (DLLME) methods based on applying low-density organic solvents have been critically compared for the speciation of inorganic selenium, Se(IV) (selenite) and Se(VI) (selenate) in environmental water samples by gas chromatography-flame ionization detection (GC-FID). At pH 2 and T = 75 °C for 7 min, only Se(IV) was able to form the piazselenol complex with 4-nitro-o-phenylenediamine. Piazselenol was extracted using an extraction solvent and was injected into a GC-FID instrument for the determination of Se(IV). Conveniently, Se(VI) remained in the aqueous phase. Total inorganic selenium was determined after the reduction of Se(VI) to Se(IV) and prior to the above procedures. The Se(VI) concentration was calculated as the difference between the measured total inorganic selenium and Se(IV) content. The effect of various experimental parameters on the efficiencies of the two methods and their optimum values were studied with the aid of response surface methodology and experimental design. Under the optimal conditions, the limit of detections (LODs) for Se(IV) obtained by USAEME-GC-FID and DLLME-GC-FID were 0.05 and 0.11 ng mL−1, respectively. The relative standard deviations (RSDs, n = 6) for the measurement 10 ng mL−1 of Se(IV) were 5.32% and 4.57% with the enrichment factors of 2491 and 1129 for USAEME-GC-FID and DLLME-GC-FID, respectively. Both methods were successfully applied to the analysis of inorganic selenium in different environmental water samples and certified reference material (NIST SRM 1643e). 相似文献
135.
Azizolla Beheshti William Clegg Nahid Ebrahimi Filoori Luca Russo 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):m149-m153
Two polymorphs of the title compound, (C8H20N)[W2S4(S4)(C15H22BN6)], have been obtained unexpectedly by attempted recrystallization of a mixed‐metal–sulfur cluster complex from different solvents. The dinuclear complex anion contains WV in two different coordination environments, one of them distorted octahedral with a tris(pyrazolyl)borate anion, a terminal sulfide and two bridging sulfide ligands, the other distorted square‐pyramidal with a terminal sulfide, two bridging sulfide and a chelating tetrasulfide ligand. The three independent anions in the two polymorphs have essentially the same geometry. The central W2S2 ring is a slightly folded rhombus with acute angles at the S atoms, and the WS4 chelate ring is an envelope with one noncoordinating S atom as the flap. The second polymorph, with Z′ = 2 and pseudo‐inversion symmetry relating the anions of the asymmetric unit, also displays pseudo‐translation features in its layer structure, and all examined crystals were found to be twinned, possibly as a consequence of this structural feature. 相似文献
136.
Chalyavi N Troy TP Nakajima M Gibson BA Nauta K Sharp RG Kable SH Schmidt TW 《The journal of physical chemistry. A》2011,115(27):7959-7965
Gas phase excitation and emission spectra of three naphthylmethyl radical chromophores are presented. These resonance-stabilized species, 1-naphthylmethyl, 2-naphthylmethyl, and α-acenaphthenyl, each possessing an sp(2) carbon adjacent to a naphthalene moiety, are studied by resonant two-color two-photon ionization, laser induced fluorescence, and dispersed fluorescence spectroscopy. Identification of the radicals is made through a combination of dispersed fluorescence and density functional theory calculations. All three species possess spectra in the 580 nm region. The possible relevance to unidentified spectroscopic features such as the diffuse interstellar bands and emission from the Red Rectangle nebula is discussed. 相似文献
137.
In selecting sites for conservation purposes connectivity of habitat is important for allowing species to move freely within a protected area. The aim of the Reserve Network Design Problem is to choose a network of contiguous sites which maximises some conservation objective subject to various constraints. The problem has been solved using both heuristic and exact methods. Heuristic methods can handle much larger problems than exact methods but cannot guarantee an optimal solution. Improvements in both computer power and optimisation algorithms have increased the attractiveness of exact methods. The aim of this work is to formulate an improved algorithm for solving the Reserve Network Design Problem. 相似文献
138.
139.
2-(3-Chloro-2-formyl-1H-indol-1-yl) acetic acid, as a bifunctional formyl-acid, is prepared in three steps. This compound undergoes a one-pot, four-center, three-component Ugi reaction with primary amines and alkyl isocyanides. A series of novel substituted indoloketopiperazine derivatives are obtained in moderate to high yields. 相似文献
140.
Vishkaee Tehereh Sadigh Fazaeli Reza 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(9):1860-1860
Russian Journal of Physical Chemistry A - The name of the first author should read Tehereh Sadigh Vishkaee. 相似文献