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991.
992.
Antonino Arcoria Emanuele Maccarone Gaetano A. Tomaselli 《Journal of heterocyclic chemistry》1973,10(2):191-194
The nitration of trans-2-styrylthiophene in carbon tetrachloride, nitroethane and acetic anhydride has been investigated. The nitration products were: β-nitro-2-styrylthiophene as the main product with 3-nitro-2-styrylthiophene and the 5-nitro isomer in smaller amounts. They were identified by the chromato-graphic and spectroscopic (uv and nmr) comparison with the reference compounds. The isomer percentages, determined by glc, were unchanged under different nitration conditions (time, temperature and molar ratio), but were dependent on the solvent used. 相似文献
993.
Gauthier S Quebatte L Scopelliti R Severin K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(11):2811-2821
Methods for the synthesis of bimetallic complexes in which two different metal fragments are connected by three chloro or bromo bridges are reported. The reactions are general, fast, and give rise to structurally defined products in quantitative yields. Therefore, they are ideally suited for generating a library of homo- and heterobimetallic complexes in a combinatorial fashion. This is of special interest for applications in homogeneous catalysis. Selected members of this library were synthesized and comprehensively characterized; single-crystal X-ray analyses were performed for 15 new bimetallic compounds. 相似文献
994.
Alberti A Canè F Dembech P Lazzari D Ricci A Seconi G 《The Journal of organic chemistry》1996,61(5):1677-1681
Amidocuprates, derived from organocopper reagents and lithium amides upon exposure to oxygen at low temperature, provide new amine derivatives in satisfactory yields. Details of this flexible and simple methodology are given. The reaction mechanism is analyzed in terms of an oxidative intramolecular coupling of aminyl radicals with the ligands on Cu in the intermediate amidocuprate. This reaction is a mild and efficient method for N-alkylation, -vinylation, and -arylation by which a number of amines, not easily accessible by normal routes, can be synthesized. Once applied to lithium hydrazides, it also provides a new and straightforward entry to N-substituted hydrazines. 相似文献
995.
996.
Herbert Motschi Cornelius Nussbaumer Paul S. Pregosin Fiorella Bachechi Pasquale Mura Luigi Zambonelli 《Helvetica chimica acta》1980,63(7):2071-2086
1H- and 13C-NMR. data are reported for the complexes [Pt (1) L] and [Pt (2) L]; 1 = OC6H4CH ? NCH2CH2O, 2 = OC6H4CH ? NC6H4O; L = PR3, AsR3, C ? N (cyclohexyl), DMSO, pyridine, secondary amine. The molecular structures of [Pt (2) (NHEt2)] (I) and [Pt (2) (PPh3)] (II) have been determined by X-ray analysis. Relevant bond distances for I: Pt-N (amine) = 2.076 Å, Pt-N (imine) = 2.017 Å, Pt-O = 1.992 Å and 2.002 Å; for II: Pt-P = 2.248 Å, Pt-N = 2.064 Å, Pt-O = 1.964 and 2.005 Å. Both the solid and solution state data are interpreted in terms of differences in the trans influence of the ligand L. The question of metal-ligand d-p π back bonding to the imine is discussed. 相似文献
997.
Riccardo Giachetti Emanuele Sorace Riccardo Ricci 《Letters in Mathematical Physics》1980,4(4):297-300
The geometrical and mechanical aspects of a particle interacting with a Poincaré gauge field are considered and the relation with a gravitational interaction is studied. 相似文献
998.
Mihaela Badea Laura Micheli Maria Cristina Messia Tiziana Candigliota Emanuele Marconi Toby Mottram Maria Velasco-Garcia Danila Moscone Giuseppe Palleschi 《Analytica chimica acta》2004,520(1-2):141-148
A flow-injection immunoassay (FI-IA) method with amperometric detection for aflatoxin M1 (AFM1) determination in milk has been developed. The first step consists in an incubation of the sample containing AFM1 (Ag) with fixed amounts of anti-AFM1 antibody (Ab) and of the tracer (Ag*, AFM1 covalently coupled to HRP) until equilibrium is reached. In this mixture a competition occurs between Ag and Ag* for the Ab. The mixture is then injected into a flow system where the separation of the free tracer (Ag*) and the antibody-bound tracer (AbAg*) is performed in a column with immobilized Protein G. The antigen–antibody complexes are retained in the column due to the high affinity of the Protein G for the antibody. The activity of the eluted enzyme label is then amperometrically detected.
The immunoassay was optimised relative to conditions for antibody–antigen incubation (pH, incubation time, ionic strength, temperature) and enzymatic label detection. This method showed a dynamic concentration range between 20 and 500 ppt AFM1, a low detection limit (11 ppt), good reproducibility (RSD < 8%) and a high throughput (six samples per hour in triplicate). Different milk samples were analysed and the results were in good agreement with those obtained by HPLC using the AOAC 2000.08 method. 相似文献
999.
1000.
A. De Pasquale G. Costantini P. Facchi G. Florio S. Pascazio K. Yuasa 《The European physical journal. Special topics》2008,160(1):127-138
We diagonalize the XX model with a finite number
of spins and periodic boundary conditions. We solve for the ground
state, focus on the rapidity of the convergence to the thermodynamic
limit and study the features of multipartite entanglement. 相似文献