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31.
Synthesis of 2‐Unsubstituted 1,3‐Selenazoles by Cyclization of Selenoformamide with α‐Bromocarbonyl Compounds 下载免费PDF全文
Harald Below Wolf‐Diethard Pfeiffer Karlheinz Geisler Ashot S. Saghyan Christine Fischer Peter Langer 《Journal of heterocyclic chemistry》2015,52(2):592-596
2‐Unsubstituted 1,3‐selenazoles were prepared by cyclization of selenoformamide with α‐bromoacetophenones. Parent 1,3‐selenazole was prepared by cyclization of selenoformamide with α‐bromoacetaldehyde. 相似文献
32.
Cyclometalated Iridium(III) Complexes Containing Semicarbazone Ligands: Synthesis,Characterization, Photophysical and Biological Studies 下载免费PDF全文
Marion Graf Yvonne Gothe Nils Metzler‐Nolte Rafał Czerwieniec Karlheinz Sünkel 《无机化学与普通化学杂志》2015,641(10):1798-1802
The synthesis, crystal structure, photophysical properties, and biological activity of the novel bis‐cyclometalated complexes [Ir(ptpy)2(vnsc)] ( 2 ) and [Ir(ptpy)2(acsc)] ( 3 ) [ptpy = 2‐(p‐tolyl)pyridinato, vnsc = vanillin semicarbazone, acsc = acetone semicarbazone] are described. The new compounds were prepared by the reaction of [{Ir(μ‐Cl)(ptpy)2}2] ( 1 ) with the corresponding semicarbazone ligands under basic conditions. The molecular structure of compound 3 was confirmed by a single‐crystal X‐ray diffraction study. The complex crystallized from chloroform as a mono‐ solvate in the orthorhombic space group Pcab with eight molecules in the unit cell. 相似文献
33.
We propose a new notion of variable bandwidth that is based on the spectral subspaces of an elliptic operator where p > 0 is a strictly positive function. Denote by the orthogonal projection of Ap corresponding to the spectrum of Ap in ; the range of this projection is the space of functions of variable bandwidth with spectral set in Λ. We will develop the basic theory of these function spaces. First, we derive (nonuniform) sampling theorems; second, we prove necessary density conditions in the style of Landau. Roughly, for a spectrum the main results say that, in a neighborhood of , a function of variable bandwidth behaves like a band‐limited function with local bandwidth . Although the formulation of the results is deceptively similar to the corresponding results for classical band‐limited functions, the methods of proof are much more involved. On the one hand, we use the oscillation method from sampling theory and frame‐theoretic methods; on the other hand, we need the precise spectral theory of Sturm‐Liouville operators and the scattering theory of one‐dimensional Schrödinger operators. © 2017 Wiley Periodicals, Inc. 相似文献
34.
Monobromoferrocene (1) was obtained in 95% yield from ferrocene via lithiation with tert-BuLi/KO-tert-Bu and bromination with dibromotetrachloroethane. Starting from 1 mixtures of 1,2-dibromoferrocene (2) and apparently unreacted 1 (ranging from 80:20 to 50:50, depending on the reaction conditions) can be obtained via a lithiation- zincation- bromination sequence. These mixtures can be transferred directly with a tenfold excess of Lithium-tetramethylpiperidinide, followed by bromination with 1,1,2,2-tetrabromoethane to pentabromoferrocene (3), in an overall yield of 36% starting from ferrocene. The molecular structures of 3 and of 1,2,3-tribromoferrocene (4) have been determined by X-Ray diffraction. 相似文献
35.
36.
To be able to meet the demands of low emissions and fuel consumption ofmodern combustion engines, new ways have to be found to control thecombustion. We use new sensors to measure the pressure in the combustionchamber and analyze this signal with a neural network in order to receiveseveral form factors which can be used to control the ignition timing. Theneural network is trained off line with measured data and used on line toderive the form factors. The proposed algorithm can be computed in real timeon conventional digital signal processors and adapted to new engines withvery little effort. 相似文献
37.
Roland Rieger Karlheinz Ballschmiter 《Fresenius' Journal of Analytical Chemistry》1995,352(7-8):715-724
A municipal sewer system has been investigated for the sources of a set of semivolatile compounds, such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (4,4'-DDE), and chlorinated paraffins (CP), using sewer films as the sampling medium. A cleanup method for these semivolatile compounds in sewer films is described. The project has been undertaken for the differentiation and localization of specific inputs of xenobiotics from defined regions of the city. A unique pattern of PCDD/PCDF found in sewage sludge has led to the search for a specific source within the sewer system, which has finally been localized as a distinct plant. Other organochlorine compounds proved to be significant indicators for industrial and domestic sewers. PCB appeared as an industry correlated parameter, while 4,4'-DDE indicated domestic sewers. Chlorinated paraffins have been detected in the mg/kg range and are markers and indicators for metal-working industries. Finally, the release of CP by the sewage treatment plant, into the nearby river, has been investigated.Dedicated to Professor Dr. Dr. h.c. mult. J. F. K. Huber on the occasion of his 70th birthday 相似文献
38.
Karlheinz Gröchenig 《Advances in Computational Mathematics》2003,18(2-4):149-157
It is shown that every localized frame is a finite union of Riesz sequences. This is a partial solution to a question of Feichtinger. 相似文献
39.
A study of the Xαβ-exchange approximation on atoms for use in molecular and solid-state calculations
Karlheinz Schwarz 《Chemical physics》1975,7(1):94-99
The Xαβ exchange approximation is applied to atoms and its universal (Z-independent) character is demonstrated. Its practical applicability to molecules and solids is critically analysed by a comparison with the Xα- and HF approximations. The influence of the modifying function which is needed to make the exchange inhomogeneity correction (β-term) finite for large r is studied. The validity of the virial theorem is discussed. 相似文献
40.
Karlheinz Spallek 《Mathematische Annalen》1977,227(3):277-286
Ohne Zusammenfassung 相似文献