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排序方式: 共有161条查询结果,搜索用时 18 毫秒
1.
Hooda Anjli Dalal Anuj Nehra Kapeesha Singh Sitender Kumar Sumit Singh Devender 《Journal of fluorescence》2022,32(4):1413-1424
Journal of Fluorescence - A series of europium diketonate complexes with 1-phenyl-1,3-butanedione (PBD) and 1,10-phenanthroline derivatives were synthesized and explored spectroscopically.... 相似文献
2.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
3.
Yogesh B. Wagh Swapnil A. Padvi Pramod P. Mahulikar Dipak S. Dalal 《Journal of heterocyclic chemistry》2020,57(3):1101-1110
A newer, versatile, and straightforward synthetic strategy for the construction of functionalized spirooxindole-pyran annulated heterocycles is described. The procedure is based on CsF-promoted rapid tandem Knoevenagel-Michael-Cyclocondensation reaction of isatin, malononitrile, and 4-hydroxycoumarin/barbituric acids/pyrazolone at room temperature in ethanol. This methodology has various advantages like easy operational, excellent yields within short reaction time (3-25 min), and simple isolation of products. The CsF has a dual role as a base and carbonyl activator. 相似文献
4.
Laura Febvay Erwann Hamon Raphaël Recht Nicolas Andres Mathilde Vincent Dalal Aoudé-Werner Hervé This 《Magnetic resonance in chemistry : MRC》2019,57(9):589-602
Roasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called “coffee” is known. In the industry, the “roasting profile,” that is, the times and temperatures applied, is key to influence the composition of roasted coffee beans and the flavour of the beverage made from them. The impact of roasting on the chemical composition of coffee has been the subject of numerous studies, including by nuclear magnetic resonance (NMR) spectroscopy. However, the roasting equipment and profiles applied in these studies are often far from real industrial conditions. In this work, the effects of two critical technological parameters of the roasting process, namely, the “development time” (the period of time after the “first crack,” a characteristic noise due to seed disruption) and the final roasting temperature on coffee extracts, were investigated. Seeds were roasted at pilot scale according to 13 industrial roasting profiles and extracted in D2O. The extracts were analysed by 1H NMR experiments. The NMR spectra were compared using (a) quantitative analysis of main signals by successive orders of magnitude and (b) chemometric tools (principal component analysis, partial least squares and sparse-orthogonal partial least squares analysis). This allowed to identify compounds, which may serve as markers of roasting and showed that changes in chemical composition can be detected even for slight change in final temperature (~1°C) or in total roasting time (~25 s). 相似文献
5.
Hemant P. Narkhede Uttam B. More Dipak S. Dalal Nilesh S. Pawar Dhananjay H. More 《合成通讯》2013,43(4):573-577
Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach. 相似文献
6.
Dipak R. Patil Pravin G. Ingole Kripal Singh Dipak S. Dalal 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(3-4):327-332
The inclusion complex of isatoic anhydride with β-cyclodextrin was formed as a result of intermolecular interaction between isatoic anhydride with β-CD. The inclusion complex was confirmed by IR spectroscopy, X-ray diffraction and DSC studies. From application of complex, herein we have described a simple and efficient protocol for synthesis of 2, 3-dihydroquinazoline-4(1H)-one derivatives by one pot condensation of isatoic anhydride, ammonium acetate or amine and aldehyde using β-CD as a supramolecular catalyst in aqueous media. 相似文献
7.
Securines A—E, three dimeric diarymethane derivatives ( 1 — 3 ) and two enantiomeric diarymethane derivative monomers ( 4 and 5 ), were isolated and characterized from the medicinal plant Securidaca inappendiculata. Compounds 1 and 2 are a pair of enantiomeric diarymethane derivative dimers, and compound 3 is a mesomeric diarymethane derivative dimer. Their structures were determined by a combination of spectroscopic data, X‐ray crystallography, electronic circular dichroism (ECD) analysis, and computational ECD calculations. Dimeric compounds 1 — 3 showed moderate antiplasmodial activities with IC50 values of 0.9, 1.4, and 1.5 μM, respectively. 相似文献
8.
We introduce the special volume “The theory and applications of uncertainty”. 相似文献
9.
In this paper, we describe a multifrequency spectroscopic system which is ideally suited to EPR investigations of very small
single crystals. Our method utilizes oversized resonant cavities and a continuously tunable vector network analyzer. This
system provides excellent sensitivity over a broad frequency range from about 30 GHz up to about 120 GHz, and in magnetic
fields up to 33 T. 相似文献
10.
A study of differently polarized structures relevant to the H-bonded antiferroelectric (AFE) compound NH(4)H(2)PO(4) (ADP) is performed by first-principles calculations in the framework of the density functional theory. The calculated structures for the AFE and paraelectric (PE) phases are found in general good agreement with the available experimental data. We study the energetics and relative stability of different polarized clusters embedded in a PE matrix of ADP. We find that local ferroelectric and AFE clusters are stable and may coexist in the PE phase, which explains the coexistence of both type of microregions determined by electron spin probe measurements above the AFE-PE transition temperature. The dependency with the O-H···O bridge length of the energy barrier heights for proton transfer is studied for coordinated proton displacements along the bridges within clusters of different sizes. This dependency may have implications for the geometric isotopic effects on T(c). We analyze Mulliken orbital and bond populations which confirm the existence of a charge flow within the NH(4)(+) ion, an essential fact for the stabilization of the AFE phase over other possible polarized structures. This charge transfer is correlated with the optimization of the N-H···O bridges and with distortions of the NH(4)(+) group. 相似文献