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41.
Ervand G. Paronikyan Shushanik Sh. Dashyan Suren S. Mamyan Armen G. Ayvazyan 《Journal of heterocyclic chemistry》2021,58(10):1936-1942
New and effective methods for the synthesis of derivatives of pyrano[3,4-c][1,2,4]triazolo[4,3-a][1,5-a]pyridines were developed. Synthesized new tetracyclic heterocyclic systems containing pyrano[3,4-c]pyridine ring unknown in the literature were obtained for the first time. The rearrangement of Dimroth in the triazolo[4,3-a]pyridine systems for the first time was studied. The possibility of rearrangement of Dimroth in the new heterocyclic system has been investigated. 相似文献
42.
Naderi Mahnaz Shamirian Armen Edrisi Mohammad 《Journal of Sol-Gel Science and Technology》2011,58(2):557-563
In the present work nano crystalline copper aluminate (CuAl2O4) has been synthesized by the Pechini method using aqueous solutions containing corresponding metal nitrates. A Taguchi L4 statistical design was employed for investigating the most effective factors on the synthesis conditions and their interactions
and production optimization. Nano crystalline CuAl2O4 particles with crystal size between 17 and 26 nm were obtained. The product characterized by XRD, FT-IR, DLS and TGA. The
morphological properties have investigated using SEM. The photocatalytic degradation was investigated using methyl orange
under the irradiation of visible light. 相似文献
43.
Inside Back Cover: A Major Advance in the Synthesis of Fluoroalkyl Pyrazoles: Tuneable Regioselectivity and Broad Substitution Patterns (Chem. Eur. J. 32/2016) 下载免费PDF全文
44.
Armen Sergeev 《中国科学A辑(英文版)》2009,52(12):2714-2729
We discuss the twistor quantization problem for the classical system (V
d
,A
d
), represented by the phase space V
d
, identified with the Sobolev space H
01/2 (S
1,ℝ
d
) of half-differentiable vector functions on the circle, and the algebra of observables A
d
, identified with the semi-direct product of the Heisenberg algebra of V
d
and the algebra Vect(S
1) of tangent vector fields on the circle. 相似文献
45.
A procedure to analyze ethyl carbamate (EC) by gas chromatography/mass spectrometry was optimized and validated. Deuterated EC (d5-EC) was added to the samples as an internal standard followed by extraction with polystyrene crosslinked polystyrene cartridges using minimal volumes of ethyl acetate. The EC response was measured in selective ion monitoring (SIM) mode and found to be linear in the range between the limit of quantitation (10 micro/L) and 1000 microg/L. EC recoveries varied from 92 to 112%, with the average value of 100 +/- 8%. The procedure compared well (r2 = 0.9970) with the existing AOAC Official Method with the added benefits of minimal solvent usage and reduced matrix interferences. 相似文献
46.
Two separate laser diodes emitting near 980 nm were coupled by a thick volume Bragg grating recorded in a photothermorefractive glass. The coupled diodes emitted at the same wavelength with a spectral width narrowed to below the resolution of the spectrum analyzer (<30 pm). Coherent emission at a pumping level greater than five times above the threshold was observed for several months with near-unity visibility of the interference pattern. 相似文献
47.
Armen S. Asratian 《Graphs and Combinatorics》2006,22(2):153-160
For a vertex w of a graph G the ball of radius 2 centered at w is the subgraph of G induced by the set M2(w) of all vertices whose distance from w does not exceed 2. We prove the following theorem: Let G be a connected graph where every ball of radius 2 is 2-connected and d(u)+d(v)≥|M2(w)|−1 for every induced path uwv. Then either G is hamiltonian or for some p≥2 where ∨ denotes join.
As a corollary we obtain the following local analogue of a theorem of Nash-Williams: A connected r-regular graph G is hamiltonian if every ball of radius 2 is 2-connected and for each vertex w of G.
Supported by the Swedish Research Council (VR) 相似文献
48.
Beaumont S Ilardi EA Tappin ND Zakarian A 《European journal of organic chemistry》2010,2010(30):5743-5765
This microreview provides a compilation of synthetic approaches and total syntheses of pinnatoxin A in a survey of the literature up to early 2010. Pinnatoxin A is the first discovered and representative member of a fascinating group of potent marine toxins that share a spiroimine subunit as a unifying structural element. 相似文献
49.
A (3, 4)-biregular bigraph G is a bipartite graph where all vertices in one part have degree 3 and all vertices in the other part have degree 4. A path
factor of G is a spanning subgraph whose components are nontrivial paths. We prove that a simple (3,4)-biregular bigraph always has a
path factor such that the endpoints of each path have degree three. Moreover we suggest a polynomial algorithm for the construction
of such a path factor. 相似文献
50.
The solid-phase library synthesis of trisubstituted guanidines was accomplished. Amines were loaded onto the 4-formyl-3,5-dimethoxyphenoxymethyl linker via reductive amination. Subsequent acylation with Fmoc-4-aminomethylbenzoic acid followed by Fmoc deprotection gave solid-supported primary amines. Alternatively, sulfonylation of resin-bound secondary amines with 4-cyanobenzenesulfonyl chloride followed by borane reduction also gave solid-supported primary amines. Both resins were acylated with isocyanates to furnish solid-supported ureas. Dehydration of ureas with p-toluenesulfonyl chloride in pyridine gave solid-supported carbodiimides. Nucleophilic addition of amines to the carbodiimide bond followed by cleavage off the solid support gave trisubstituted guanidines. 相似文献