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101.
Cellulose - Wood modification treatments by substitution or blocking of wood hydroxyl groups with hydrophobic molecules are some of the novel approaches that may improve dimensional stability,... 相似文献
102.
We report herein a combined experimental–computational study on tris‐(2‐hydroxylethyl)methylammonium methylsulfate in water solutions, as a representative ionic liquid of the aqueous‐solution behavior of hydroxylammonium‐based ionic liquids. Relevant thermophysical properties were measured as a function of mixture composition and temperature. Classical molecular dynamics simulations were performed to infer microscopic structural features. The reported results for ionic liquid in water‐rich solutions show that it behaves as isolated non‐interacting ions solvated by water molecules, through well‐defined solvation shells, exerting a disrupting effect on the water hydrogen bonding network. Nevertheless, as ionic liquid concentration increase, interionic association increases, even for diluted water solutions, evolving from the typical behavior of strong electrolytes in solution toward large interacting structures. For ionic‐liquid‐rich mixtures, water exerts a minor disrupting effect on the fluid’s structuring because it occupies regions around each ion (developing water–ion hydrogen bonds) but without significantly weakening anion–cation interactions. 相似文献
103.
A sensitive, selective, simple and fast HPLC method based on the formation of derivative with fluorescamine was developed for the determination of memantine (ME) in human plasma. Separation was achieved on a CN column (200 mm×4.6 mm) using acetonitrile-10 mM orthophosphoric acid containing 1 mL/L triethylamine (45:55, v/v) at a flow rate of 1 mL/min. Emission and excitation wavelengths were 480 and 380 nm, respectively. Amantadine was used as an internal standard. Calibration graphs were rectilinear over the range of 1.0-100.0 ng/mL. Limit of detection and limit of quantification were found to be 0.3 and 1.0 ng/mL, respectively. Intra-day and inter-day relative standard deviation values were found to be <2.03%. Average recovery was also found to be around 94%. Proposed method was applied for the pharmacokinetic study in a healthy volunteer after a single oral administration of 20 mg of ME. 相似文献
104.
105.
The [Cu(acac)2]‐catalyzed reactions of various α,β,γ,δ‐unsaturated bis‐ketones/bis‐esters/bis‐keto esters with dimethyl diazomalonate and ethyl diazoacetate were studied. Total steric/electronic convenience of the present reaction paths was investigated. Methoxy/nitro substituents in m‐/p‐positions on benzylidene biscarbonyls did not alter the general routes of the reactions, supporting concerted mechanism. Dihydrobenzoxepine/oxepine formation was sterically sensitive to the related pre‐ring conformation, and dihydrofurans were effected by both charge control and steric factors. 相似文献
106.
This paper studies torsional wave dispersion in a three-layered (sandwich) hollow cylinder with finite initial strains. The investigations are carried out within the scope of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies. The mechanical relations of the materials of the cylinders are described through their harmonic potential. The analytical expression is obtained for the low wavenumber limit values of the torsional wave propagation velocity. The numerical results on the influence of the initial stretching or compression of the cylinders along the torsional wave propagation direction are presented and discussed. 相似文献
107.
Utility of the Pfitzinger Reaction in the Synthesis of Novel Quinoline Derivatives and Related Heterocycles
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Derviş Gök Rahmi Kasımoğulları Mustafa Cengiz Samet Mert 《Journal of heterocyclic chemistry》2014,51(1):224-232
2‐(2‐Amino‐3,5‐dinitrophenyl)‐2‐oxoacetic acid ( 2 ) was obtained from hydrolysis of 5,7‐dinitroisatin ( 1 ) in alkaline media. A novel quinoxaline derivative ( 3 ) was synthesized from the reaction of the same compound ( 1 ) with o‐phenylenediamine. Reacting 2 with ethyl 3‐oxo‐3‐phenylpropanoate yields 6,8‐dinitro‐2‐phenylquinoline‐3,4‐dicarboxylic acid ( 4 ). Then, 4 was converted into new quinoline‐diacylchloride, quinoline‐ester, quinoline‐dicarboxamide, pyridazine, and pyrroledione derivatives ( 5 , 6a , 6b , 6c , 6d , 7a , 7b , 7c , 7d , 8 , 9 , 10a , 10b , 10c , 10d , 11a , 11b , 12 ) with SOCl2, alcohols, amines, and hydrazines, respectively. The structures of synthesized compounds were clarified by 1H NMR, 13C NMR, IR, mass and elemental analysis methods. 相似文献
108.
As a consequence of more extensive collaboration between countries, the need for better humanitarian relief assistance has
become a significant challenge to the international community. In case of a disaster exceeding the national response capacity
of the affected country, donor countries provide the relief items, which are then consolidated at collection points to be
shipped to points of delivery in the stricken country. After the items are transported to the point of delivery, the responsible
authority in distributing aids to vulnerable populations then becomes the national relief agencies. In this context, we propose
an international relief planning model that can handle the uncertain information while maximizing the credibility of the international
agencies in the most cost efficient way. 相似文献
109.
The method which we call the Weighted Averaging Based on Levels (WABL) can be used to calculate the average representative
of a fuzzy number. It utilizes weight coefficients for the level sets as well as the sides of a fuzzy number. We have developed
an algorithm to obtain these coefficients. The most remarkable feature of this algorithm is that it makes use of the decision
maker’s (DM) aggregation strategy. 相似文献
110.
Fadime Mert‐Balci Hans‐Georg Imrich Jürgen Conrad Uwe Beifuss 《Helvetica chimica acta》2013,96(9):1681-1692
The three‐component reaction of aniline, benzaldehyde, and dienophiles such as 2,3‐dihydrofuran, ethyl vinyl ether, 2,3‐dihydropyran, and cyclopentadiene can be promoted by ionic liquids like imidazolium salts and guanidinium salts under thermal as well as microwave conditions. The chemical yield as well as the diastereoselectivity of the Povarov reaction strongly depend on the ionic liquid employed. The guanidinium salts can be recycled and reused several times without loss of reactivity. 相似文献