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Martin Kucha? 《Tetrahedron》2008,64(45):10355-10364
Dihydroxylation of 6-vinylpurines with t-BuOOH and OsO4 gave 6-(1,2-dihydroxyethyl)purines 2, while the epoxidation with H2WO4 and t-BuOOH afforded 6-(oxiran-2-yl)purines 3. Oxirane ring-opening reactions of 3 with diverse nucleophiles gave a series of title 6-(1,2-disubstituted ethyl)purine bases and nucleosides, which were tested for cytostatic and antiviral activities. 相似文献
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Eva Pospíšilová Natálie Paškanová Martin Kuchař Tatiana V. Shishkanova 《Electroanalysis》2023,35(6):e202200468
This work presents a potentiometric approach for the detection of two cathinone derivatives, namely mephedrone (4-MMC) and clephedrone (4-CMC). Contrary to neutral-carriers (dibenzo-18-crown-6-ether and calix[4]arene), cation-exchanger (tetraphenylborate sodium) as active component of ion-selective membrane showed near-Nernstian response (+47 mV/decade from 1.7 ⋅ 10−6 to 5.6 ⋅ 10−4 mol l−1) and selectivity for 4-MMC in oral fluids (OF). The agreement between the quantitative results obtained with the potentiometric approach and the HPLC/MS-MS method determination of 4-MMC in OF shows the potential of the proposed potentiometric approach for forensic analysis. 相似文献
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K. Kuchař 《Czechoslovak Journal of Physics》1963,13(8):551-557
Similarly as in the Rainich geometrization of an electromagnetic field, the author finds a system of differential equations for the metric tensor, equivalent to the equations of the gravitational and scalar meson field, and shows how to find the wave function of the meson field if the Ricci tensor is known. 相似文献
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K. Kuchař 《Czechoslovak Journal of Physics》1968,18(4):435-463
The boundary conditions for the gravitational and electromagnetic fields on charged shells are formulated. The shells are characterized in geometrical terms and the boundary conditions are manifestly covariant. The formalism is applied to the study of the gravitational collapse of homogeneous charged spherical shells. The law of conservation of energy, obtained by integrating the equations of motion of the shell and interpreted in full analogy with the special theory of relativity, is the starting point in analyzing the equilibrium states and the motion of the shells. It is concluded that no charge, however high it may be, can stop the gravitational collapse of the shell below the upper Nordström radius. 相似文献