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61.
[reaction: see text]. A concise total synthesis of (+/-)-deguelin was achieved with a longest linear sequence of six steps in 68% yield. A key step was the platinum-catalyzed 6-endo hydroarylation of an alkynone intermediate. 相似文献
62.
Govindaswami Ragupathi Susan F. Slovin Sucharita Adluri Dalibor Sames In Jong Kim Hyunjin M. Kim Maria Spassova William G. Bornmann Kenneth O. Lloyd Howard I. Scher Philip O. Livingston Samuel J. Danishefsky 《Angewandte Chemie (International ed. in English)》1999,38(4):563-566
Human trials on the globo H carbohydrate vaccine (see picture, KLH=the carrier protein keyhole limpet hemocyanin) show that it produces strong IgM, and in some cases IgG, responses in patients with progressive and recurrent prostate cancer. Furthermore, these antibodies not only recognize synthetic antigens, but also globo H‐positive tumors in biopsy extracts and tumor tissues. 相似文献
63.
Milan Mikula Michal Čeppan Juraj Kindernay Dalibor Búc 《Czechoslovak Journal of Physics》1999,49(3):393-403
Three sets of titanium oxide layers with different oxygen content were prepared by DC pulsed reactive magnetron sputtering. The layers were characterised by their thickness, conductivity, refractive index, band-gap and flat band potential. The photoelectric and photocatalytic activities of the layers irradiated by Xe discharge lamp were tested in NaOH and phenol water solution, respectively. Rather high activity of prepared layers was found; no expressive activity increase was, however, observed in contrary to the expectation connected with suboxide forms of TiO
x
. 相似文献
64.
65.
Dalibor Merunka 《Solid State Communications》2004,129(6):375-377
The modified strong dipole-proton coupling (MSDPC) model, which predicted several static and dynamic dielectric properties of KH2PO4 or KDP-type ferroelectrics, was used to investigate the properties of these crystals on the local scale. Results calculated by molecular dynamics (MD) simulation show that both order-disorder and displacive characteristics of one PO4 dipole are present in KDP and KD2PO4 (DKDP). These results correlate with experimental data from NMR and neutron scattering studies of local properties. 相似文献
66.
Ar-Rh(III) pivalate complexes assembled in situ from the reaction of [RhCl(coe)2]2 (coe = cis-cyclooctene), [p-(CF3)C6H4]3P, and CsOPiv effectively catalyzed the direct C-arylation of free (NH)-indoles and (NH)-pyrroles in good yields and with high regioselectivity. The reaction displayed excellent functional group compatibility and low moisture sensitivity. Kinetics studies support a mechanism involving phosphine displacement by indole in complex 2 (resting state of the catalyst), followed by a rate-limiting C-H bond metalation. 相似文献
67.
The development of a new chemical transformation, namely oxidative C-arylation of saturated (NH)-heterocycles, is described. This reaction combines dehydrogenation and arylation in one process, leading to cross-coupling of (NH)-heterocycles and haloarenes. Typical reaction conditions involve heating the reaction partners in anhydrous dioxane at 120-150 degrees C in the presence of RhCl(CO)[P(Fur)3]2 as the catalyst and Cs2CO3 as the base. Addition of tert-butylethylene as the hydrogen acceptor increases the chemical yield by diminishing the dehalogenation pathway. This method demonstrated a good substrate scope, allowing for cross-coupling of a variety of (NH)-heterocycles (e.g., pyrrolidine, piperidine, piperazine, morpholine) and halo(hetero)arenes to afford valuable heterocyclic products in one step. The preliminary mechanistic studies provided some insight regarding the key events in the proposed catalytic cycle, including beta-hydride elimination of an amido rhodium complex and carbometalation of the resulting imine. A large kinetic isotope effect [KIE (kC-H/kC-D) = 4.3] suggests that one or both beta-hydride elimination steps are rate determining. The central role for the phosphine ligand was established in controlling the partitioning between the oxidative C-arylation and N-arylation pathways. 相似文献
68.
On Solution to an Optimal Shape Design Problem in 3-Dimensional Linear Magnetostatics 总被引:2,自引:0,他引:2
Dalibor Lukáš 《Applications of Mathematics》2004,49(5):441-464
In this paper we present theoretical, computational, and practical aspects concerning 3-dimensional shape optimization governed by linear magnetostatics. The state solution is approximated by the finite element method using Nédélec elements on tetrahedra. Concerning optimization, the shape controls the interface between the air and the ferromagnetic parts while the whole domain is fixed. We prove the existence of an optimal shape. Then we state a finite element approximation to the optimization problem and prove the convergence of the approximated solutions. In the end, we solve the problem for the optimal shape of an electromagnet that arises in the research on magnetooptic effects and that was manufactured afterwards. 相似文献
69.
We establish an invariance principle for a general class of stationary random fields indexed by Zd, under Hannan’s condition generalized to Zd. To do so we first establish a uniform integrability result for stationary orthomartingales, and second we establish a coboundary decomposition for certain stationary random fields. At last, we obtain an invariance principle by developing an orthomartingale approximation. Our invariance principle improves known results in the literature, and particularly we require only finite second moment. 相似文献
70.
Jan Tborský Josef Sus Jaromír Lachman Barbora ebkov Aneka Adamcov Dalibor atínský 《Molecules (Basel, Switzerland)》2021,26(13)
Apple trees (Malus domestica Borgh) are a rich source of dihydrochalcones, phenolic acids and flavonoids. Considering the increasing demand for these phytochemicals with health-benefitting properties, the objective of this study was to evaluate the profile of the main bioactive compounds—phloridzin, phloretin, chlorogenic acid and rutin—in apple tree bark, leaves, flower buds and twigs. The variety in the phenolic profiles of four apple tree cultivars was monitored during the vegetation period from March to September using chromatography analysis. Phloridzin, the major glycoside of interest, reached the highest values in the bark of all the tested cultivars in May (up to 91.7 ± 4.4 mg g−1 of the dried weight (DW), cv. ‘Opal’). In the leaves, the highest levels of phloridzin were found in cv. ‘Opal’ in May (82.5 ± 22.0 mg g−1 of DW); in twigs, the highest levels were found in cv. ‘Rozela’ in September (52.4 ± 12.1 mg g−1 of DW). In the flower buds, the content of phloridzin was similar to that in the twigs. Aglycone phloretin was found only in the leaves in relatively low concentrations (max. value 2.8 ± 1.4 mg g−1 of DW). The highest values of rutin were found in the leaves of all the tested cultivars (10.5 ± 2.9 mg g−1 of DW, cv. ‘Opal’ in September); the concentrations in the bark and twigs were much lower. The highest content of chlorogenic acid was found in flower buds (3.3 ± 1.0 mg g−1 of DW, cv. ‘Rozela’). Whole apple fruits harvested in September were rich in chlorogenic acid and phloridzin. The statistical evaluation by Scheffe’s test confirmed the significant difference of cv. ‘Rozela’ from the other tested cultivars. In conclusion, apple tree bark, twigs, and leaves were found to be important renewable resources of bioactive phenolics, especially phloridzin and rutin. The simple availability of waste plant material can therefore be used as a rich source of phenolic compounds for cosmetics, nutraceuticals, and food supplement preparation. 相似文献