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排序方式: 共有496条查询结果,搜索用时 31 毫秒
121.
Mylavarapu S. Sastry Suryakant S. Gupta Amar Jit Singh 《Transition Metal Chemistry》1994,19(4):421-425
Summary Facile reaction of 2,2,6,2-terpyridine (L; terpy) with copper or zinc powders or their mixtures, in the presence of an excess of H2O2, leads to novel complexes [Cu(L)-(O2
2–)]·3H2O, [Zn(L)(O
2
2–
)]·H2O and [Cu,Zn(L)2(O
2
2–
)2]· 4H2O, respectively, which were isolated and characterized by elemental and micro- analysis, e.s.r., electronic, i.r. and thermogravimetric analysis in air and argon. 相似文献
122.
The 1,3-dipolar cycloaddition of nitrile oxides to 1-cyanoenamines gives 5-aminoisoxazoles regioselectively. Moderate to good yields could be obtained depending on the method used to generate the nitrile oxides. The intermediate isoxazolines could not be isolated. 相似文献
123.
124.
M. A. Kabil S. E. Ghazy M. A. Shallaby M. R. Lasheen N. S. Amar 《Fresenius' Journal of Analytical Chemistry》1996,354(3):371-373
A highly selective and sensitive procedure for flotation separation followed by spectrophotometric determination, confirmed by AAS, of Ni(II) traces is proposed. The maximum flotation separation (100%) is achieved at 25° C in the pH range of 1–3 using sodium diethyldithiocarbamate (as a collector) and oleic acid surfactant. The floated (1 : 2) colored complex is measured spectrophotometrically at 430 nm over a concentration range of 0.5–4.0 g/g with a molar absorptivity of 0.44 × 104 L mol–1 cm–1. The procedure was successfully applied for the separation and determination of Ni(II) in fresh and sea waters. 相似文献
125.
Peichun Li Amar Zerroukhi Jianding Chen Yvan Chalamet Thomas Jeanmaire Zhean Xia 《Journal of polymer science. Part A, Polymer chemistry》2008,46(23):7773-7784
Ti[O(CH2)4OCH?CH2]4, used for the ring‐opening polymerization (ROP) of ε‐caprolactone, was synthesized through the ester‐exchange reaction of titanium n‐propoxide and 1,4‐butanediol vinyl ether, and its chemical structure was confirmed by nuclear magnetic resonance (1H NMR) and thermogravimetric analysis (TGA). The mechanism and kinetics of Ti[O(CH2)4OCH?CH2]4‐initiated bulk polymerization of ε‐caprolactone were investigated. The results demonstrate that Ti[O (CH2)4OCH?CH2]4‐initiated polymerization of ε‐caprolactone proceeds through the coordination‐insertion mechanism, and all the four alkoxide arms in Ti[O (CH2)4OCH?CH2]4 share a similar activity in initiating ROP of ε‐caprolactone. The polymerization process can be well predicted by the obtained kinetic parameters, and the activation energy is 106 KJ/mol. Then, the rheological method was employed to investigate the feasibility of producing the crosslinked poly(ε‐caprolactone)‐poly (n‐butyl acrylate) network by using Ti[O(CH2)4OCH?CH2]4 as the ROP initiator. The tensile test demonstrates that the in situ generated crosslinked PCL‐PBA network in PMMA matrix provides the possibility of ameliorating the tensile properties of PMMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7773–7784, 2008 相似文献
126.
Vladimir Chechersky Nikolai S. Kopelev Beom-hoan O Michael I. Larkin Jian-Liang Peng John T. Markert Richard L. Greene Amar Nath 《Hyperfine Interactions》1994,93(1):1721-1726
Mössbauer effect studies suggest the presence of extraneous oxygen in the whole family of title compounds. At certain concentrations of Ce, oxygen is rather tenaciously bound. Such oxygen causes superparamagnetism in the magnetically ordered material, and also brings about the formation of spin clusters in the metallic material. 相似文献
127.
The main result of this paper establishes that the irregularity strength of any tree with no vertices of degree two is its number of pendant vertices. 相似文献
128.
Amar Maheshwari 《Pramana》1986,27(3):383-391
The complete expression of the five-dimensional Einstein-Hilbert action as an expansion in fields in the Appelquist-Chodos
parametrization of the Kaluza-Klein metric has been given in this paper. It is explicitly shown that a unitary gauge can be
fixed in which in each of the charge sectors the vector and the scalar fields are absorbed as Goldstone modes leaving behind
the Pauli-Fierz Lagrangian for massive charged spin-2 field. 相似文献
129.
Two-dimensional flows with suction or mass loss are investigated within Darcy’s or Stokes’ framework. Examples include a Hele-Shaw
cell with a lifted plate or extraction of lipids from a lipid bilayer. An initially circular patch ret-racts due to the suction
and might undergo an instability whereby it becomes undulating. The selection of the wavelength of undulations is investigated
with the help of an extremum principle, the minimization of the generalized dissipation, from which derive the flow equations. 相似文献
130.
J. W. Hewage F. G. Amar M.-F. de Feraudy G. Torchet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):249-252
Using realistic pair potentials, we investigate the
structures of mixed clusters of argon and nitrogen in order to
interpret the experimental electron diffraction patterns
reported by the Torchet group. Simulations of small clusters
indicate that argon tends to segregate at the center of the
clusters. For larger clusters, in the range of 50 to 200
molecules, MC methods have been used to simulate structures that
are likely to be generated in the molecular beam. By comparing
predicted electron diffraction patterns with those recorded in
the experiments, our models allow us to estimate the average
size and composition of the mixed clusters for a given set of
experimental conditions (nozzle stagnation pressure and Ar
partial pressure). 相似文献