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排序方式: 共有214条查询结果,搜索用时 15 毫秒
91.
92.
Solution Combustion Synthesis (SCS) and ConventionalCeramic Process (CCP) were applied for the preparation of magnesium pyroborate (Mg2B2O5) from Mg(NO3)2 · 6H2O and H3BO3. Structural and morphological properties of the products were comparatively examined by XRD and FT‐IR spectroscopic measurements as well as SEM and BET techniques. The effects of synthesis conditions on the properties of products were investigated throughly by optimizing the B/Mg molar ratio and reaction duration in CCP and by optimizing the fuel (carbohydrazide) quantity in SCS. Pure Mg2B2O5 (triclinicsuanite) was obtained by thermal treatment in CCP employing a B/Mg molar ratio of 3:1. It was found that the fuel must be in close proximity to the stoichiometric requirements in order to obtain the desired product in highly crystalline form from SCS. The Mg2B2O5 samples obtained by both methods exhibited similar structural properties but different morphologies. 相似文献
93.
Abstract Graft polymerization of acrylamide (AAm) on 1, 1, 2, 2 tetrachloro-ethane (TCE) preswelled poly(ethylene terephthalate) (PET) films were performed with chemical initiation method using asobisiso-butyronitrile (AIBN) initiator. Temperature was found to have a greater effect on the swelling then the swelling time. Variation of the graft yield with polymerization temperature, time, AIBN concentration, AAm concentration, AIBN and AAm inclusion times were investigated. The optimum temperature for grafting was found to be 70°CC. The graft yield was observed to increase with polymerization time, AAm concentration, initiator and monomer diffusion time up to a saturation graft yield and then leveled off. An increase in AIBN concentration first enhanced the percent grafting then showed a decrease. The addition of some salts (Ni2+, Cr3+, Co2+, Cu2+) on the rate of grafting was also investigated. From the temperature dependence of the initial rate of grafting, the overall activation energy was found to be 4. 1 kcal/mol and relevant rate equation have been derived. The effect of grafting on film propities, such as water absorption capacity, intrinsic viscosity were determined. Grafted films were characterized by FTIR spectros-copy and scanning electron microscopy (SEM). 相似文献
94.
Yılmaz Turgut Murat Azizoglu Aslı Erdogan Nevin Arslan Halil Hosgoren 《Tetrahedron: Asymmetry》2013,24(13-14):853-859
In order to find the most effective catalyst for the enantioselective reduction of a prochiral ketone, a series of novel β-hydroxyamide derivatives of salicylic acid and chiral amino alcohols were synthesized. Different substituted prochiral ketones have been reduced in high yield (up to 99%) and the corresponding secondary alcohols are formed with good enantiomeric excess (up to 86%). The mechanism of this type of catalyst can be explained by considering the reaction mechanism for the CBS catalyst. 相似文献
95.
Nergiz Cengiz Halil Kabadayioglu Rana Sanyal 《Journal of polymer science. Part A, Polymer chemistry》2010,48(21):4737-4746
A novel N‐hydroxy succinimide‐based carbonate monomer that allows direct synthesis of polymers incorporating a reactive carbonate group in the side chain was synthesized. This new monomer was copolymerized with methyl methacrylate and poly(ethylene glycol) methylether methacrylate using free‐radical polymerization to obtain organo‐ and water‐soluble reactive copolymers. Copolymerization of the activated carbonate monomer with an azide‐containing monomer and N‐hydroxy succinimide‐containing activated ester monomer provided orthogonally functionalizable copolymers. The pendant reactive carbonate groups of the copolymers were functionalized with amines to obtain carbamates. Polymers capable of orthogonal functionalization could be selectively functionalized as desired using subsequent 1,3‐dipolar cycloaddition or amidation reactions. The novel monomer and the copolymers were characterized by 1H‐NMR, 13C‐NMR, and infrared spectroscopy. The efficient stepwise orthogonal functionalization of the copolymers were examined via 1H‐NMR spectroscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
96.
Angle-resolved X-ray photoelectron spectroscopy and contact-angle measurements guided by a signal attenuation model are utilized to extract molar composition and anion enrichment in the vacuum interface of a binary ionic liquid mixture, having a common quaternary ammonium cation and two different anions. By using the intensity ratio of the F1s peaks belonging to the two different anions recorded at the full electron take-off angle range, from 0° to 80°, we have determined that only a fractionally covered and anion enriched surface layer can predict the AR-XPS data, which is also consistent with surface tension measurements. Moreover, the more bulky and non-spherical anion enrichment is evident even at the conventional and the so assumed bulk sensitive take-off angle of 0°. This methodology provides a surface enrichment factor of the molecular ions and clearly serves as an experimental evidence for recently debated surface layering and/or island structure in ionic liquid systems. 相似文献
97.
98.
Şahan Halil Göktepe Hüseyin Patat Şaban Yıldız Süleyman Özdemir Burcu Ülgen Ahmet Mukerjee Sanjeev Abraham K. M. 《Journal of Solid State Electrochemistry》2019,23(5):1593-1604
Journal of Solid State Electrochemistry - In this work, a Li-rich layered 0.5Li2MnO3.0.5LiMn1/3Ni1/3Co1/3O2 (LMNCO) pristine cathode material synthesized with a glycine-nitrate combustion method is... 相似文献
99.
C(2)-Symmetric two bis(amino alcohol)oxalamides (diamidediols) were synthesized and fully characterized. A new method was developed and successfully applied for the simultaneous preconcentration of both trace and toxic metals in water, by using C(2)-symmetric compounds. Under the optimum experimental conditions (i.e. pH = 10.0 +/- 0.2, 2.75 x 10(-3) mol L(-1) N,N'-bis[(1R)-1-ethyl-2-hydroxyethyl]ethanediamide (DAD1), 1.75 x 10(-3) mol L(-1) N,N'-bis[(1S)-1-benzyl-2-hydroxyethyl]-ethanediamide (DAD2), 0.10% w/v octylphenoxy-polyethoxyethanol (Triton X-114)), calibration graphs were linear in the range of 2.5 - 25.0 ng mL(-1) for Cu and Cd, 5.0 - 25.0 ng mL(-1) for Co and Ni. The enrichment factors were 18, 23, 18 and 20 for Cd, Cu, Co and Ni in the case of DAD1, respectively; 20, 22, 17 and 20 for Cd, Cu, Co and Ni in the case of DAD2. The limits of detection for DAD1 were found to be 0.45, 0.50, 1.25 and 0.60 ng mL(-1) for Cd, Cu, Co and Ni, respectively, and for DAD2 were found to be 0.44, 0.25, 0.60 and 1.55 ng mL(-1) for Cd, Cu, Co and Ni, respectively. The developed method was applied to the determination of Cu, Cd, Co and Ni in water samples and certified reference materials with satisfactory results. 相似文献
100.
An affine de Casteljau type algorithm to compute q-Bernstein Bézier curves is introduced and its intermediate points are obtained explicitly in two ways. Furthermore we define
a tensor product patch, based on this algorithm, depending on two parameters. Degree elevation procedure is studied. The matrix
representation of tensor product patch is given and we find the transformation matrix between a classical tensor product Bézier
patch and a tensor product q-Bernstein Bézier patch. Finally, q-Bernstein polynomials B
n,m
(f;x,y) for a function f(x,y), (x,y)∈[0,1]×[0,1] are defined and fundamental properties are discussed.
AMS subject classification (2000) 65D17 相似文献