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排序方式: 共有1425条查询结果,搜索用时 15 毫秒
931.
Agnieszka Wasilewska Bartosz A. Woźniak Dr. Gabriel Doridot Kamila Piotrowska Natalia Witkowska Dr. Pascal Retailleau Dr. Yvan Six 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(35):11759-11767
The acid‐catalysed thermal rearrangements of a family of N‐aryl 2‐azabicyclo[3.1.0]hexanes is described. These substrates, designed in such a way that the aromatic system is conjugated with an alkene group located at the ortho position relative to the nitrogen atom, have been prepared by using an intramolecular Kulinkovich–de Meijere reaction. The rearrangements can then be conducted either under standard thermal conditions or with microwave activation. Depending on the conditions applied and the substitution pattern, dihydroquinoline or polycyclic aminocyclobutane derivatives can be obtained. A mechanistic discussion is provided, with the proposition of the initial protonation of the aminocyclopropane moiety to give an iminium intermediate. By analogy with related intermolecular reactions, the involvement of electrocyclic reactions among the series of elementary steps that follow is put forward. 相似文献
932.
Agata Siwek Monika Wujec Maria Dobosz Ewa Jagiełło-Wójtowicz Agnieszka Kleinrok Anna Chodkowska 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2669-2677
Three 3-(thiophen-2-yl)-4-substituted-Δ 2 -1,2,4-triazoline-5-thiones were synthesized by intramolecular cyclization of 1-(thiophen-2-ylcarbonyl)-4-substituted thiosemicarbazides in alkaline medium. Their effects on the central nervous system (CNS) of mice in some behavioral tests were investigated. All investigated compounds displayed antinociceptive activity. The correlation between the structural features and bioactivity has been discussed. 相似文献
933.
Agnieszka Stawarska Tomasz Lepionka Agnieszka Biaek Martyna Gawryjoek Barbara Bobrowska-Korczak 《Molecules (Basel, Switzerland)》2020,25(22)
Pomegranate seed oil (PSO) and bitter melon dried fruits (BME) are used as natural remedies in folk medicine and as dietary supplements. However, the exact mechanism of their beneficial action is not known. The aim of study was to assess how the diet supplementation with PSO and/or with an aqueous solution of Momordica charantia affects the metabolism of fatty acids, fatty acids composition and the level of prostaglandin E2 (PGE2) in rat liver. Animals (Sprague-Dawley female rats, n = 48) were divide into four equinumerous groups and fed as a control diet or experimental diets supplemented with PSO, BME or both PSO and BME for 21 weeks. Fatty acids were determined using gas chromatography with flame ionization detection. PSO added to the diet increased the rumenic acid content (p < 0.0001) and increased accumulation of n-6 fatty acids (p = 0.0001) in hepatic tissue. Enrichment of the diet either with PSO or with BME reduced the activity of Δ6-desaturase (D6D) (p = 0.0019), whereas the combination of those dietary factors only slightly increased the effect. Applied dietary supplements significantly reduced the PGE2 level (p = 0.0021). No significant intensification of the influence on the investigated parameters resulted from combined application of PSO and BME. PSO and BME have potential health-promoting properties because they influence fatty acids composition and exhibit an inhibiting effect on the activity of desaturases and thus they contribute to the reduction in the metabolites of arachidonic acid (especially PGE2). 相似文献
934.
Aneta Sulborska Agata Konarska Anna Matysik-Wo
niak Marta Dmitruk Elbieta Weryszko-Chmielewska Agnieszka Skalska-Kamiska Robert Rejdak 《Molecules (Basel, Switzerland)》2020,25(24)
Flos Lamii albi has a high biological activity and is widely used in herbal medicine. The aim of the study was to characterize the secretory structures present in Lamium album subsp. album corolla and the location of phenolic compounds. Additionally, we carried out qualitative phytochemical analyses of flavonoids and phenolic acids. Light, fluorescence, and scanning electron microscopy were used to analyze the structure of the floral organs. The main classes of phenolic compounds and their localization were determined histochemically. Phytochemical analyses were performed with high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). Six types of glandular trichomes were found which contained flavonoids, phenolic acids, and tannins. The phytochemical studies demonstrated the presence of caffeic, chlorogenic, ferulic, gallic, p-coumaric, protocatechuic, syringic, gentisic, and vanillic phenolic acids as well as rutoside, isoquercetin, and quercetin flavonoids. The corolla in L. album subsp. album has antioxidant properties due to the presence of various polyphenols, as shown by the histo- and phytochemical analyses. The distribution and morphology of trichomes and the content of phenolic compounds in the corolla have taxonomic, pharmacognostic, and practical importance, facilitating the identification of the raw material. 相似文献
935.
Oleksandr Romanyuk Oliver Supplie Agnieszka Paszuk Jan Philipp Stoeckmann Regan George Wilks Jakob Bombsch Claudia Hartmann Raul Garcia-Diez Shigenori Ueda Igor Bartoš Ivan Gordeev Jana Houdkova Peter Kleinschmidt Marcus Bär Petr Jiříček Thomas Hannappel 《Surface and interface analysis : SIA》2020,52(12):933-938
We present a study of buried GaP/Si(001) heterointerfaces by hard X-ray photoelectron spectroscopy. Well-defined thin (4–50 nm) GaP films were grown on Si(001) substrates with 2° miscut orientations by metalorganic vapor phase epitaxy. Core level photoelectron intensities and valence band spectra were measured on heterostructures as well as on the corresponding reference (bulk) substrates. Detailed analysis of core level peaks revealed line broadening and energetic shifts. Valence band offsets were derived for the films with different thickness. Based on the observed variation of the valence band offsets with the GaP film thickness and on the experimental evidence of line broadening, the existence of charge displacement at the GaP/Si(001) interface is suggested. 相似文献
936.
Chip‐based capillary electrophoresis profiling of olive pollen extracts used for allergy diagnosis and immunotherapy 下载免费PDF全文
Agnieszka Zienkiewicz Krzysztof Zienkiewicz Fernando Florido Francisco Manuel Marco Pedro José Romero Antonio Jesus Castro Juan de Dios Alché 《Electrophoresis》2014,35(18):2681-2685
Standardization of protein extracts for clinical purposes represents an important task in order to maintain adequate reactivity, presence of the relevant allergens, and safety among other factors. The main objective of this work was to explore the potential use of a chip‐based automated CE system commercially available to analyze several of the most common forms of allergenic extracts from olive pollen used in allergy clinics. These include experimental extracts prepared from olive pollens, in‐house reference extracts, extracts designed for skin prick test assays, and a panel of vaccine variants aimed to specific immunotherapy. As a major conclusion of the study, chip‐based CE allowed in all cases to determine accurate protein profiles with different degrees of sensitivity, where several allergens (particularly the major olive pollen allergen Ole e 1) were easily recognized. Moreover, several purified allergens were also analyzed by this method, and proposed as specific standards for different purposes. In the present condition, the method can only provide the protein profile of the extracts with respect to a preestablished standard extract, but not allergen identification. However, these and other future developments and applications are discussed. 相似文献
937.
Bioelectricity Production from Soil Using Microbial Fuel Cells 总被引:2,自引:0,他引:2
Agnieszka Wolińska Zofia Stępniewska Arletta Bielecka Jakub Ciepielski 《Applied biochemistry and biotechnology》2014,173(8):2287-2296
Microbial fuel cells (MFCs) are a device using microorganisms as biocatalysts for transforming chemical energy into bioelectricity. As soil is an environment with the highest number of microorganisms and diversity, we hypothesized that it should have the potential for energy generation. The soil used for the study was Mollic Gleysol collected from the surface layer (0–20 cm). Four combinations of soil MFC differing from each other in humidity (full water holding capacity [WHC] and flooding) and the carbon source (glucose and straw) were constructed. Voltage (mV) and current intensity (μA) produced by the MFCs were recorded every day or at 2-day intervals. The fastest and the most effective MFCs in voltage generation (372.2?±?5 mV) were those constructed on the basis of glucose (MFC-G). The efficiency of straw MFCs (MFC-S) was noticeable after 2 weeks (319.3?±?4 mV). Maximal power density (P max?=?32 mW m?2) was achieved by the MFC-G at current density (CD) of 100 mA m?2. Much lower values of P max (10.6–10.8 mW m?2) were noted in the MFC-S at CD of ca. 60–80 mA m?2. Consequently, soil has potential for production of renewable energy. 相似文献
938.
939.
Lucie Smoláková árka Botková Libor apek Peter Priecel Agnieszka Soltysek Martin Kout Lenka Matějová 《催化学报》2013,34(10):1905-1913
Ni/Al2O3 catalysts for oxidative dehydrogenation(ODH) of ethane were prepared by impregnation of Al2O3 with nickel acetate or nickel nitrate,and by mechanical mixing of NiO and Al2O3.The Ni-based catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,diffuse reflectance UV-visible diffuse reflectance spectroscopy,and temperature-programmed reduction of hydrogen.The results showed that formation of crystalline NiO particles with a size of < 8 nm and/or non-stoichiometric NiO species in the Ni/Al2O3 catalysts led to more active species in ODH of ethane under the investigated reaction conditions.In contrast,tetrahedral Ni species present in the catalysts led to higher selectivity for ethene.Formation of large crystalline NiO particles(22-32 nm) over Ni/Al2O3 catalysts decreased the selectivity for ethene. 相似文献
940.
Dr. Jacek Ściebura Dr. Agnieszka Janiak Agata Stasiowska Dr. Jakub Grajewski Dr. Krystyna Gawrońska Prof. Dr. Urszula Rychlewska Prof. Dr. Jacek Gawroński 《Chemphyschem》2014,15(8):1653-1659
Trityl group, Tr, is a molecular dynamic rotor of which the conformation and helicity depend on other groups in the close vicinity. Interactions with another covalently linked Tr group and with other substituents are analyzed in terms of transfer of chirality to the trityl group. Two trityl groups in a molecule can mutually interact at a distance of two, three, or five bonds. Despite its size, a Tr group attached to a cyclohexane or cyclopentane ring through an oxygen or nitrogen atom adopts either an axial or equatorial position, depending on additional stabilizing interactions, such as hydrogen bonding. 相似文献