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991.
Nadhomi Timothy Okeke Chisom Prince Sablik Maciej Szostok Tomasz 《Aequationes Mathematicae》2021,95(6):1095-1117
Aequationes mathematicae - The classical result of L. Székelyhidi states that (under some assumptions) every solution of a general linear equation must be a polynomial function. It is known... 相似文献
992.
Piotr de Silva Prof. Jacek Korchowiec Prof. Tomasz A. Wesolowski 《Chemphyschem》2012,13(15):3462-3465
We introduce a new tool (single exponential decay detector: SEDD) to extract information about bonding and localization in atoms, molecules, or molecular assemblies. The practical evaluation of SEDD does not require any explicit information about the orbitals. The only quantity needed is the electron density (calculated or experimental) and its derivatives up to the second order. 相似文献
993.
Isoquinoline alkaloids may have a wide range of pharmacological activities. Some of them have acetylcholinesterase activity inhibition. Nowadays, neurodegenerative disorders such as Alzheimer’s disease have become a serious public health problem. Searching for new effective compounds with inhibited acetylcholinesterase activity is one of the most significant challenges of modern scientific research. The aim of this study was the in vitro investigation of acetylcholinesterase activity inhibition of extracts obtained from Sanguinaria canadensis collected before, during and after flowering. The acetylcholinesterase activity inhibition of these extracts has not been previously tested. The aim was also to quantify selected alkaloids in the investigated extracts by high performance liquid chromatography (HPLC). The analyses of alkaloid content were performed using HPLC in reversed phase (RP) mode using Polar RP column and mobile phase containing acetonitrile, water and ionic liquid (IL). The acetylcholinesterase activity inhibition of the tested plant extracts and respective alkaloid standards were examined using high performance liquid chromatography with diode-array detector (HPLC-DAD) for the quantification of 5-thio-2-nitro-benzoic acid, which is the product of the reaction between the thiocholine (product of the hydrolysis of acetylthiocholine reaction) with Ellman reagent. The application of the HPLC method allowed for elimination of absorption of interfering components, for example, alkaloids such as sanguinarine and berberine. It is revealed that the HPLC method can be successfully used for the evaluation of the acetylcholinesterase inhibitory activity in samples such as plant extracts, especially those containing colored components adsorbing at wavelength in the range 405–412 nm. The acetylcholinesterase inhibition activity synergy of pairs of alkaloid standards and mixture of all investigated alkaloids was also determined. Most investigated alkaloids and all Sanguinaria canadensis extracts exhibited very high acetylcholinesterase activity inhibition. IC50 values obtained for alkaloid standards were from 0.36 for berberine to 23.13 µg/mL for protopine and from 61.24 to 89.14 µg/mL for Sanguinaria canadensis extracts. Our investigations demonstrated that these plant extracts can be recommended for further in vivo experiments to confirm their acetylcholinesterase activity inhibition. 相似文献
994.
Krzysztof Durka Krzysztof Gontarczyk Tomasz Kliś Janusz Serwatowski Krzysztof Woźniak 《应用有机金属化学》2012,26(6):287-292
Lithium diisopropylamine (LDA)‐mediated deprotonation reactions of halogenated cyanobenzyloxy‐benzenes and cyanobiphenyls were investigated. The resultant organolithium derivatives were converted into the corresponding arylboronic acids or silanes. It was found that the stability of the obtained aryllithiums towards isomerization to the respective benzyllithiums depends strongly on the number of fluorine atoms in the phenyl ring and on the position of the cyano group. Halogenated cyanobiaryls were selectively deprotonated in the position flanked by two halogen atoms; however, the yield depended strongly on the reaction conditions. Addition of LDA to the cyano group was observed on the lithiation of 4‐cyano‐3′,5′‐dichlorobiphenyl rather than deprotonation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
996.
Tomasz Pietrzak Dr. Iwona Justyniak Jiwon Victoria Park Michał Terlecki Łukasz Kapuśniak Prof. Janusz Lewiński 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2503-2510
Despite decades of extensive studies on the reactivity of magnesium alkyls towards O2, the isolation and structural characterization of discrete products of these reactions still remains a challenge. Although the formation of the most frequently encountered magnesium alkoxides through unstable alkylperoxide intermediates has commonly been accepted, the latter species have been elusive for over 100 years. Probing the oxygenation of a seemingly simple well-defined neo-pentylmagnesium complex stabilized by a β-diketiminate ligand, (dippBDI)MgCH2CMe3, we report on the isolation and structure characterization of both a dimeric magnesium alkoxide [(dippBDI)Mg(μ-OCH2CMe3)]2 and the first example of monomeric magnesium alkylperoxide [(dippBDI)Mg(thf)OOCH2CMe3] (dippBDI=[(ArNCMe)2CH]− and Ar=C6H3iPr2-2,6). The formation of monomeric magnesium alkylperoxide demonstrates a crucial role of an additional Lewis base for stabilizing the most elusive oxygenation products likely due to increasing of the electron density on the metal centre. Moreover, the 1H NMR studies at −80 °C revealed that the dissociation of a coordinated Lewis base from the solvated complex (dippBDI)Mg(L)CH2CMe3 (where L=thf or 4-methylpyridine) is likely not required prior to the effective attack of an O2 molecule on the metal centre and the four-coordinate alkylmagnesium complex reacts smoothly with O2 under these conditions. The results can be expected to aid future engineering of various organomagnesium/O2-based reaction systems. 相似文献
997.
Katarzyna awiska Szymon Szufa Remigiusz Modrzewski Andrzej Obraniak Tomasz Wyk Andrzej Rostocki Tomasz P. Olejnik 《Molecules (Basel, Switzerland)》2020,25(22)
This paper presents the results of research on the granulation process of leather industry waste, i.e., tanning shavings. It is economically justified to granulate this waste together with mineral additives that are useful in the processes of their further processing. Unfortunately, the granulation of raw, unsorted shavings does not obtain desired results due to their unusual properties. In this study, the possibilities of agglomeration of this waste were examined by a new method consisting of the production and then the granulation of wet pulp. During granulation, no additional binding liquid is added to the granulated bed. As part of this work, the specific surface of granulated shavings, the granulometric composition of the obtained agglomerates, and their strength parameters were determined. The use of a vibrating disc granulator, the addition of a water glass solution (in the pulp), dolomite, and gypsum made it possible to obtain durable, mechanically stable granules. 相似文献
998.
Gaozhan Xie Miriam Hauschild Hendrik Hoffmann Lukas Ahrens Dr. Frank Rominger Michal Borkowski Dr. Tomasz Marszalek Dr. Jan Freudenberg Prof. Milan Kivala Prof. Uwe H. F. Bunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(4):799-803
The synthesis, property evaluation, and single crystal X-ray structures of four 5,7,12,14-tetrafunctionalized diazapentacenes are presented. The synthesis of these compounds either starts from tetrabromo-N,N-dihydrodiazapentacene or from a diazapentacene tetraketone. Pd-catalyzed coupling or addition of a lithium acetylide gave the precursors that furnish, after further redox reactions, the diazapentacenes as stable crystalline materials. The performance of the tetraphenyl-substituted compound as n-channel semiconductor was evaluated in organic field effect transistors. 相似文献
999.
1000.
Aequationes mathematicae - We study the alienation problem for two general linear equations i.e. we compare the solutions of the system of equations $$\begin{aligned} \left\{ \begin{array}{l}\sum... 相似文献