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991.
The reactions of the mono-N-substituted bispyrazolylpyridine 2-(1-methyl-4,5,6,7-tetxahydroindazol-3-yl)-6-(2H-4,5,6,7-tetrahydroindazol-3-yl)pyridine, 3,5-dimethylpyrazole and benzimidazole with sodium hydride and diiodomethane or dibromomethane in tetrahydrofuran produced the unexpected N-tetrahydrofuran-2-yl adducts as well as the expected diazolylmethanes. These side-reactions are thought to involve the 2-halo tetrahydrofuran derivative resulting from a free-radical halogenation by the dihalomethane. 相似文献
992.
993.
Anna Stochmal Agata Rolnik Bartosz Skalski Jerzy Zuchowski Beata Olas 《Molecules (Basel, Switzerland)》2022,27(14)
Blood platelets play a crucial role in hemostasis, the process responsible for keeping blood flowing in the circulatory system. However, unnecessary platelet activation can lead to aggregation at the site of atherosclerotic plaque rapture and the formation of a thrombus, which promotes atherothrombotic diseases. Various dietary components, such as phenolic compounds, are known to demonstrate antiplatelet and anticoagulant properties, and it is possible that these could form an important element in the prophylaxis and therapy of cardiovascular diseases. Our present study examined the biological activity of isorhamnetin (1) and two isorhamnetin derivatives, (2): 3-O-beta-glucoside-7-O-alpha-rhamnoside and (3): 3-O-beta-glucoside-7-O-alpha-(3″′-isovaleryl)-rhamnoside, isolated from the phenolic fraction of sea buckthorn fruit, against human washed blood platelets and human whole blood in vitro. The anti-platelet and anticoagulant potential was determined using (A) flow cytometry, (B) the thrombus-formation analysis system (T-TAS) and (C) colorimetry. The results of the T-TAS test indicate that the AUC10 (Area Under the Curve) of the tested phenolic compounds (compounds 1, 2 and 3; 50 µg/mL) was markedly reduced compared to the control values. Moreover, flavonol demonstrated anti-platelet potential, including anti-adhesive activity, with these effects being more intense in compound 2 than isorhamnetin. Different actions of flavonol on platelet activation may depend on their binding ability to various receptors on blood platelets. However, the mechanism of their anti-platelet potential requires further additional studies, including in vitro and in vivo experiments. 相似文献
994.
Wojciech Golimowski Mirosawa Teleszko Damian Marcinkowski Dominik Kmiecik Anna Grygier Andrzej Kwanica 《Molecules (Basel, Switzerland)》2022,27(10)
In the last decade, the demand for edible niche oils has increased. Therefore, the aim of this study was to characterize the seeds hemp (Cannabis sativa L.) varieties: ‘Finola’ (FIN-314)’, ‘Earlina 8FC’, and ‘Secuieni Jubileu’, and cold and hot pressed oils were prepared from each seed. The seeds were examined for moisture content, granulometric distribution, bulk density, and fat content. Seeds were pressed without and with preconditioning (60 °C), and oil yield and pressing time were recorded. The oil was filtered through cellulose membranes. Oil–water content, oil color, fatty acid profile, and sterol content were studied. From the study conducted, there are significant differences in the parameters of oil recovery and its quality compared to ‘Finola’ seed oil, which is widely reported in the literature. ‘Finola’ oil yield was the lowest, with an average of 79% compared to ‘Earlina’ (82%) and ‘S. Jubileu’ (84%). All oil samples contained a comparable amount of sterols, with campesterol (0.32 mg/g), β-sitosterol (1.3 mg/g) and Δ5-avenasterol (0.15 mg/g) predominating. From the organoleptic evaluation, it was evident that both varieties hemp oils and marc (‘Earlina’ and ‘S. Jubileu’) were not bitter like the “Finola” oil and marc. More detailed studies in this direction have to be undertaken. 相似文献
995.
Jerzy Moc 《International journal of quantum chemistry》1999,73(1):37-43
Portions of the [S, H3, X] (X=F, Cl) potential energy surfaces (PESs) were explored using the RHF, MP2, and QCISD(T) methods with emphasis on H2 and HX eliminations, SH3X→SHX+H2 and SH3X→SH2+HX, respectively. Upon the halogen X substitution, the most favorable decomposition pathway of SH4 went over to HX elimination, proceeding with a very low activation barrier of 6.9 (X=F) and 1.3 (X=Cl) kcal/mol. Moreover, the transition states (TSs) for H2 elimination from SH3X resembled the less favorable homopolar TS of SH4. Upon the X=F substitution, the barrier to H2 loss of SH4 was calculated to increase from 19.5 to 21.5 kcal/mol. For X=Cl, only the indirect H2 elimination path via the SH2+HCl→SHCl+H2 exchange was found. The hydrogen‐exchange reaction SH2+HX→SH2+HX was predicted to occur through formation of the hydrogen‐bonded complex XHSH2 and with a relatively high barrier of 43.5 (X=F) and 38.5 (X=Cl) kcal/mol. FHSH2 and ClHSH2 were found to be the lowest energy species on the [S, H3, F] and [S, H3, Cl] PESs, lying 53.4 and 44.7 kcal/mol below SH3F and SH3Cl, respectively. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 37–43, 1999 相似文献
996.
The reaction rates of alcoholysis of isosteric silanethiols iBun(iPrO)3−nSiSH, n = 0–3, in the presence of the tertiary amines, 4-dimethylaminopyridine (DMAP) or triethylamine (NEt3), were measured in benzene and in acetonitrile solutions under pseudo-first-order conditions. The catalytic activity of NEt3 is low. The alcoholysis catalyzed by DMAP shows features of a nucleophilic catalysis. The protonation of the catalyst (DMAP or NEt3) by silanethiols causes substantial deviations from pseudo-first-order kinetics. Phenolysis of silanethiols is effectively catalyzed by both DMAP and NEt3. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 245–251, 1997. 相似文献
997.
Pawe Rociszewski Jerzy ukasiak Agnieszka Dorosz Janusz Galiski Maria Szponar 《Macromolecular Symposia》1998,130(1):337-346
Biodegradation of various polyorganosiloxanes (about 30 substances) under the influence of several biotype bacteria strain (16 types) were studied. A special procedure of biodegradation and analytical methods of evaluation the degree of degradation were applied. It was found that nearly all polysiloxanes tested are biodegradable but the degree of degradation depends on their composition and structure, as well as on the type of bacteria strain chosen. 相似文献
998.
A graph G is called well covered if every two maximal independent sets of G have the same number of vertices. In this paper, we characterize well covered simplicial, chordal and circular arc graphs. © 1996 John Wiley & Sons, Inc. 相似文献
999.
Wojciech Bocian Jerzy W. Wiench Lech Stefaniak Graham A. Webb 《Magnetic resonance in chemistry : MRC》1996,34(6):453-457
1H, 13C, 14N and 15N NMR results are reported for some mesoionic 1,2,3-triazoles and related compounds. It is demonstrated that 14N NMR linewidths are dependent on the charge present on the nitrogen atom. In addition, it is shown that nitrogen NMR is of great value in the determination of the site of protonation, the ability to distinguish readily between mesoionic cyclic and non-cyclic structures and to follow the transformation between such structures. 相似文献
1000.
Nanoparticles are presently considered the efficient carriers of medicals, cosmetics, and pharmaceuticals in the human organism. There is a lot of research carried out on the delivery of these materials in a non-invasive way. Such a method is very safe in times of global illnesses and pandemics. The most frequently investigated route is the approach to delivering nano-media through the skin as the result of diffusion processes. The stratum corneum, the outermost layer of skin, is the most resistive barrier to such a form of penetration. In this work, a new model is proposed to predict nanoparticles’ transport through this layer. It introduces the concept of the three-dimensional model of the stratum corneum, which allows to define the skin surface area from which diffusion occurs. This structure was replaced by the single capillary, resulting from theoretical considerations. Modeling of the diffusion process of nanoparticles as the result of Brownian motion in such a capillary was performed numerically using COMSOL Multiphysics package programs. Further, using the dimensions of such a capillary, a new model of diffusion was developed in which the parameters allow to determine the effective diffusion coefficient as a function of nanoparticle size and the viscosity of a liquid. As a result, the proposed models provide a new and efficient approach to the determination of the nano-molecules’ transport phenomena through the skin layer. 相似文献