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排序方式: 共有101条查询结果,搜索用时 31 毫秒
41.
Dorina Mantu Costel Moldoveanu Alina Nicolescu Calin Deleanu Ionel I. Mangalagiu 《Ultrasonics sonochemistry》2009,16(4):452-454
A new, efficient and general method for preparation of N-substituted-pyridazinones using ultrasound irradiation is reported. Under ultrasound the reaction time decreases substantially, the yields are high and the reaction conditions are mild. It was noticed that substituents at the 3-(6)-position of pyridazone heterocycle have a substantial influence on the reactivity, while the effect of the substituents at the 1-(2)-position seems to be of minor importance. A comparative study of the reactions performed under ultrasound conditions versus at room temperature has been done. 相似文献
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43.
Dan Donescu Liana Fusulan Cristian Petcu Marilena Vasilescu Calin Deleanu Silvia Udrea 《Macromolecular Symposia》2002,179(1):315-330
The microemulsion system containing vinyl acetate (Vac), silane derivatives tetraethoxysilane (TEOS), methacryloxypropyltrimethoxysilane (MPTS), vinyltriethoxysilane (VTES), methyltriethoxysilane (MeTES), octyltriethoxysilane (OTES), nonylphenol etoxylated with 25 mol of ethylene oxyde (NPEO25) and water was studied. It was established that the probability of microemulsion formation increases with surfactant concentration. The microenviroment of the solubilization of the VAc and of silane derivatives in the aggregates of NPEO25 was affected by their polarity. Hybrid materials were obtained by sol-gel reaction of silane derivatives combined with free-radical polymerization of VAc. The change of the glass transition temperature and of thermal stability of the polymer chains in the presence of the inorganic one proved the formation of simultaneous polymer inorganic hybrids. 相似文献
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45.
Pavel F. Vlad Alexandru G. Ciocarlan Calin Deleanu Oana Costan Yurii A. Simonov Janusz Lipkowski Aede de Groot 《Tetrahedron》2006,62(36):8489-8497
Valuable chiral drimanic dienic synthons have been prepared by a photolytic Norrish type II degradation of the corresponding 14,15-bisnorlabdene-13-ones. Minor by-products with unexpected bi- and tricyclic structures were formed and some of them were isolated and identified. 相似文献
46.
A novel mixed-valence polyoxomolybdenum anion, [Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3)H)(4)](3)(-), was synthesized hydrothermally from molybdenum oxide, molybdenum metal, boric and phosphoric acids, 1,2-phenyldiphosphonic acid, and imidazole (ImH) and was structurally characterized as an imidazolium salt (orthorhombic, Aba2; a = 16.674(4), b = 17.238(1), and c = 24.81(2) A). One- and two-dimensional structures of this anion and additional molybdenum diphosphonate linkers were assembled as well. They were structurally characterized as their pyridinium (pyH) salts (pyH)(4)[[Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3))(2)(O(3)PPhPO(3)H)(2)][Mo(2)O(4)(OH)(HO(3)PPhPO(3)H)]].5H(2)O (monoclinic, P2(1)/c; a = 20.8506(9), b = 22.866(1), and c = 21.1403(9) A; beta = 118.7087(8) degrees ) and (pyH)(3)[[Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3))(4)][Mo(2)O(2)(OH)(2)(HO(3)PPhPO(3)H)]].3H(2)O (orthorhombic, Pca2(1); a = 19.057(1), b = 20.402(2), and c = 20.660(2) A). The compounds were also characterized by IR spectroscopy and magnetic measurements. 相似文献
47.
David C Companys E Galceran J Garcés JL Mas F Rey-Castro C Salvador J Puy J 《The journal of physical chemistry. B》2008,112(33):10092-10100
Stepwise constants can be used to describe competitive proton and metal binding to macromolecules with a large number of sites. With the aim of accessing information on the microscopic binding model, we report an expression that connects the stepwise constants to the site-specific metal constants. This expression holds for a very general complexation model including heterogeneity, interactions, and chelate complexation. Assuming bidentate binding of the Cd ions to adjacent carboxylate groups in poly(acrylic acid), stepwise and intrinsic stability constants for proton and cadmium binding were estimated from the experimental data. Intrinsic values were split into specific and electrostatic contributions (by means of the Poisson-Boltzmann equation under cylindrical geometry). Free of the electrostatic contribution, the remaining Cd binding energy showed almost no dependence on the coverage and ionic strength, and the corresponding average values allowed for a reasonable reproduction of raw binding data. Small systematic discrepancies from the homogeneous behavior are critically discussed. 相似文献
48.
A Molecular Pillar Approach To Grow Vertical Covalent Organic Framework Nanosheets on Graphene: Hybrid Materials for Energy Storage
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Dr. Jinhua Sun Alexey Klechikov Calin Moise Dr. Mariana Prodana Prof. Marius Enachescu Prof. Alexandr V. Talyzin 《Angewandte Chemie (International ed. in English)》2018,57(4):1034-1038
Hybrid 2D–2D materials composed of perpendicularly oriented covalent organic frameworks (COFs) and graphene were prepared and tested for energy storage applications. Diboronic acid molecules covalently attached to graphene oxide (GO) were used as nucleation sites for directing vertical growth of COF‐1 nanosheets (v‐COF‐GO). The hybrid material has a forest of COF‐1 nanosheets with a thickness of 3 to 15 nm in edge‐on orientation relative to GO. The reaction performed without molecular pillars resulted in uncontrollable growth of thick COF‐1 platelets parallel to the surface of GO. The v‐COF‐GO was converted into a conductive carbon material preserving the nanostructure of precursor with ultrathin porous carbon nanosheets grafted to graphene in edge‐on orientation. It was demonstrated as a high‐performance electrode material for supercapacitors. The molecular pillar approach can be used for preparation of many other 2D‐2D materials with control of their relative orientation. 相似文献
49.
Calin Iulian Martin 《Journal of Mathematical Fluid Mechanics》2013,15(1):155-170
We study periodic capillary waves at the free surface of water in a flow with constant vorticity over a flat bed. Using bifurcation theory the local existence of waves of small amplitude is proved even in the presence of stagnation points in the flow. We also derive the dispersion relation. 相似文献
50.
Calin Vasile Andritoiu Corina Elena Andriescu Constanta Ibanescu Cristina Lungu Bianca Ivanescu Laurian Vlase Cornel Havarneanu Marcel Popa 《Molecules (Basel, Switzerland)》2020,25(22)
The present paper aims to formulate and characterize four phytotherapeutic ointments based on Hippophae fructus, Calendulae flos, Bardanae folium, and Millefolii herba, which are included in a novel ointment base. In order to investigate the healing properties of the ointments, in vivo experimental wound models of linear incision, circular excision, and thermal burn were performed on Wistar rats. Topical treatment was performed daily for 21 days. Determination of the wound contraction rate (WCR), the period of reepithelization, and histopathological examination were achieved. Additionally, for the tested ointments, oscillatory and rotational rheological tests were carried out, and for the extracts, HPLC analysis was performed. The results demonstrate that the tested novel ointments are safe for use and the most effective ointment proved to be the one based on Arctium lappa, followed by that of Calendulae flos. 相似文献