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1.
Dalibor Nosek 《Czechoslovak Journal of Physics》1998,48(2):205-207
A simple method is used to count average numbers of different kinds of nucleon pairs within the Sp(4) seniority-like model
which describesT=1 pairing modes of protons and neutrons. These numbers as well as the total strengths of pair-transfer processes clearly
indicate that pn configurations are preferred in theN
p=N
n odd-odd systems.
Presented at Workshop on calculation of double-beta-decay matrix elements (MEDEX’97), Prague, May 27–31, 1997. 相似文献
2.
We herein report that PtCl4 has proven to be a hydroarylation catalyst with an efficiency and substrate scope superior to previously known methods. This catalyst demonstrated consistent performance with arene-yne substrates of diverse structural features, including propargyl ethers, propargylamines, and alkynoate esters, providing good to excellent yields of the 6-endo products (chromenes, dihydroquinolines, and coumarins). In contrast, Pt(II), Pd(II), and Ga(III) salts were shown to be sensitive to the substitution on the alkyne moiety. PtCl4 is compatible with both terminal and disubstituted alkynes, as well as with various functionalities on the arene ring, including methyl, methoxyl, hydroxyl, protected amine, and halide. 相似文献
3.
F. Jancik B. Seifert C. K. Laird W. Czysz J. S. Dunnett W. Schmidt und P. Bachhausen 《Fresenius' Journal of Analytical Chemistry》1987,327(7):747-755
Ohne Zusammenfassung 相似文献
4.
5.
F. Jancik W. Czysz E. Svatek M. Rittich J. S. Dunnett et al. 《Fresenius' Journal of Analytical Chemistry》1989,333(2):171-175
Abstracts2 Particular products and fields of application
2.6 Foods 相似文献6.
In this contribution, the on-line coupling of solid phase extraction (SPE), based on a restricted-access material (RAM), with sequential injection technique (SIA) for the analysis of biological samples, is described. The SIA-RAM system was tested with a new potential antileucotrienic drug (VUFB-19363 (Quinlukast)) for serum analysis. The method is based on SPE with the novel internal-surface reversed-phase column packing material-alkyl-diol silica (ADS). The supports tolerate direct and repetitive injection of proteinaceous fluids (plasma, serum) and allow reversed-phase partitioning at the internal surface. A column packed with a 25 microm C18 alkyl-diol support was used for direct serum injection. Using a 6-port selection valve and the system of three mobile phases, the polar matrix compounds and metabolites are removed by sequentially aspirated mobile phases with lower content of the organic part (methanol-water (2:98) and following acetonitrile-water (20:80)) to the waste, and then, the analyte enriched on the column is eluted by a strong mobile phase (acetonitrile-methanol-water (40:20:40)) to the UV detector without transfer loss. With the fully automated SIA system, a total analysis time of less than 10 min was achieved. The only off-line sample pre-treatment step required to remove particulate matter was centrifugation. The studies showed a range of linearity (2-40 microg ml(-1)) and a high recovery (93.6-96.8%) of drug from the biological matrix with coefficients of variation (RSD) less than 5.0% (n = 6). This paper introduces a new, simple and robust analytical technique suitable for screening determination and direct analysis of drugs in biological materials. 相似文献
7.
Direct and selective catalytic arylation of alpha-C-H bond in pyridine with iodobenzene was achieved in up to 70% yield. Phosphido-bridged bisruthenium complexes 6a and 6b arising from Ru3(CO)12 and PPh3 were identified as active catalysts. The formation of complexes 6a and 6b was investigated, a sequence of C-H and C-P bond cleavage, cluster fragmentation, and disproportionation was established, and the intermediate ruthenium complexes lying on this pathway were isolated and fully characterized. 相似文献
8.
A new system for palladium-catalyzed arylation of a broad spectrum of free (NH)-heteroarenes has been developed (indole, pyrrole, pyrazole, 2-phenylimidazole, imidazole, benzimidazole, and purine). Remarkable selectivity has been achieved in the presence of MgO base, providing single C-arylation products, while no N-arylation and no bis-arylation products have been detected. In the case of free imidazole, exclusive C-4 arylation may be switched to exclusive 2-arylation by the addition of CuI to the Pd/Ph3P/MgO system. When free aryl-(NH)-azoles are desired, direct arylation eliminates three steps in comparison to standard methods, including N-protection, stoichiometric metalation or halogenation, and N-deprotection. 相似文献
9.
F. Jancik W. Schmidt W. Czysz R. H. S. H. B. Singh et al. 《Fresenius' Journal of Analytical Chemistry》1989,335(2):241-245
Abstracts1 General analytical chemistry
1.3 Organic analysis 相似文献10.
We herein describe our studies on arylation of N-phenylpyrrolidine, which led to the development of a new transformation for the direct and selective arylation of sp3 C-H bonds in the absence of a directing group. In this method, Ru(H)2(CO)(PCy3)3 4 was used as the catalyst, and preliminary mechanistic studies suggested that Ru(Ph)(I)(CO)(PCy3)2 5 is the key intermediate of the catalytic cycle. A large kinetic isotope effect (kH/kD = 5.4) was observed, which supports the proposal that C-H bond metalation is the slow step. Preliminary examination of the substrate scope showed that in addition to N-phenylpyrrolidine, N-methyl- and N-benzylpyrrolidine, as well as N-benzoylpyrrolidine, were arylated under the reaction conditions. 相似文献