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51.
W. Schwan 《Mathematische Zeitschrift》1948,51(3):346-354
Ohne Zusammenfassung 相似文献
52.
Ohne ZusammenfassungAnmerkung der Redaktion. Die Arbeit wurde am 25. Dezember 1943 eingereicht, vor dem Druck jedoch umgearbeitet, um den Zusammenhang mit nachfolgenden Arbeiten zu verdeutlichen und diese vorzubereiten. 相似文献
53.
Ulf Vogel Karl-Christian Schwan Manfred Scheer 《Journal of organometallic chemistry》2006,691(21):4556-4564
Theoretical investigations on the thermochemistry and the reaction mechanism of the formation of Lewis acid/base stabilised phosphanyltrielanes D · H2EPH2 · A (D = Lewis base, A = Lewis acid) were conducted. The reactions of EH3 · D with A · PH3 to form D · H2EPH2 · A and H2 (E = B, Al, Ga; D = NH3; A = BH3, Cr(CO)5) are all exothermic, regardless of whether donors and acceptors are present or absent. The lithium chloride elimination reactions between EH2Cl · D and A · PH2Li to give D · H2EPH2 · A and LiCl are endothermic for donor/acceptor stabilised compounds, if formation of gaseous LiCl is considered. If solid lithium chloride is considered all reactions are strongly exothermic. Studies of the transition state for H2-elimination reactions between EH3 · D and A · PH3 to yield D · H2EPH2 · A and H2 were only successful for E = Al, Ga. In these cases the reaction proceeds via a transition state featuring a five or six-coordinate group 13 element. Different donor molecules do not influence the activation energy of such H2-elimination reactions, but nevertheless they have an effect on the reaction energy. The synthesis of the Cr(CO)5 substituted phosphanyltrielanes [(CO)5Cr(H2PBH2 · NMe3)] (3a) and [(CO)5Cr(H2PAlH2 · NMe3)] (3b), as well as of the dinuclear complex [(CO)8Cr2(μ-HPBH2 · NMe3)2] (4) are described, the latter as a subsequent reaction product of the photolysis of 3a. All compounds were characterised spectroscopically and by X-ray structure analysis. 相似文献
54.
55.
A heretofore unknown LDA-induced conversion of benzyl 1-alkynyl sulfones to 1H-2-benzothiopyran-S,S-dioxides is demonstrated. A benzyl carbanion, accessible by two means, is thought to cyclize by temporary disruption of aromaticity. Key intermediates are observed by ReactIR analysis. Thiophene derivatives are also amenable to cyclization, forming 7H-thieno[2,3-c]thiopyran-S,S-dioxides. 相似文献
56.
57.
Piyush S. Sharma Marcin Dabrowski Krzysztof Noworyta Tan-Phat Huynh Chandra B. KC Janusz W. Sobczak Piotr Pieta Francis D’Souza Wlodzimierz Kutner 《Analytica chimica acta》2014
For molecular imprinting of oxidatively electroactive analytes by electropolymerization, we used herein reductively electroactive functional monomers. As a proof of concept, we applied C60 fullerene adducts as such for the first time. For that, we derivatized C60 to bear either an uracil or an amide, or a carboxy addend for recognition of the adenosine-5′-triphosphate (ATP) oxidizable analyte with the ATP-templated molecularly imprinted polymer (MIP-ATP). Accordingly, the ATP complex with all of the functional monomers formed in solution was potentiodynamically electropolymerized to deposit an MIP-ATP film either on an Au electrode of the quartz crystal resonator or on a Pt disk electrode for the piezoelectric microgravimetry (PM) or capacitive impedimetry (CI) determination of ATP, respectively, under the flow-injection analysis (FIA) conditions. The apparent imprinting factor for ATP was ∼4.0. After extraction of the ATP template, analytical performance of the resulting chemosensors, including detectability, sensitivity, and selectivity, was characterized. The limit of detection was 0.3 and 0.03 mM ATP for the PM and CI chemosensor, respectively. The MIP-ATP film discriminated structural analogues of ATP quite well. The Langmuir, Freundlich, and Langmuir–Freundlich isotherms were fitted to the experimental data of the ATP sorption and sorption stability constants appeared to be nearly independent of the adopted sorption model. 相似文献
58.
Pseudopotential cluster calculations have been performed for hydrogen centers H0i, H0a, H0c in XF and XCl ionic crystals (X = Li, Na, K, Rb). Results are given for interatomic potentials, for frequencies of localized vibration modes and for activation energies for diffusion of the hydrogen centers. 相似文献
59.
60.
C. Schwan A. Penzkofer N. J. Marx K. H. Drexhage 《Applied physics. B, Lasers and optics》1993,57(3):203-211
The phase-matched direct tripling of picosecond light pulses of a mode-locked Nd: glass laser in a new cyanine dye PMC is studied. The solvents trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP) are applied. The S
0–S
1 absorption peak of the dye is around =480 nm and the absorption cross section at the third-harmonic wavelength of 3=351.3 nm is only 31×10–19 cm2. Phase-matching occurred at concentrations of CPM=0.0874 mol/dm3 in HFIP and 0.1088 mol/dm3 in TFE. A third-harmonic energy conversion efficiency of E0.01 was achieved at a pump-laser peak intensity of I
0L2.5×1011 W/cm2 in a 5 mm long sample of PMC in TFE. The conversion efficiency is limited by destruction of phase-matching due to the intensity-dependent nonlinear refractive index of the dye solutions. 相似文献