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201.
John W-P. Lin Les P. Dudek 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1579-1587
Dark blue poly(copper 2,3,9,10,16,17,23,24-octacyanophthalocyanine) has been prepared by reacting 1,2,4,5-tetracyanobenzene with cuprous chloride in 1-methyl-2-pyrrolidone at ca. 150°C. The product has been characterized by elemental analysis, thermal analysis, infrared and UV-VIS spectroscopies. The polymer has high purity and exhibits good thermal stability in an inert atmosphere. 相似文献
202.
Michael M. King Herman J. C. Yeh Gerald O. Dudek 《Magnetic resonance in chemistry : MRC》1976,8(4):208-212
A series of 15N labeled 2-acylpyrroles was prepared and the nitrogen and proton n.m.r. spectra obtained. 15N chemical shifts for these compounds are reported for the first time. No correlation between the nitrogen chemical shift and any Hammett substituent constant could be found. No variation in J(15N? H) was observed for any compound with changes in solvent, temperature or concentration, ruling out any observable tautomeric equilibria for these systems. An increase in J(15N? H) with the addition of electron withdrawing groups indicates increasing polarization of the N? H bond and acidity of these molecules. Two and three bond 15N couplings are also reported. 相似文献
203.
Properties of n-ary groups connected with the affine geometry are considered. Some conditions for an n-ary rs-group to be derived from a binary group are given. Necessary and sufficient conditions for an n-ary group
-derived from an additive group of a field to be an rs-group are obtained. The existence of non-commutative n-ary rs-groups which are not derived from any group of arity m<n for every n3, r>2 is proved. 相似文献
204.
Single crystals of benzophenone-2-furoyl hydrazone are grown by slow evaporation solution growth technique from ethanol at room temperature. It belongs to monoclinic system with the space group P21/c and the cell parameters are, a = 6.1631(3) Å, b = 13.1397(8) Å, c = 18.0030(11) Å and V = 1457.72(14) Å3. NMR spectral studies reveal the structure and powder XRD indicates the crystallinity of the specimen. The characteristic functional groups present in the molecule are confirmed by Fourier transform infrared spectroscopy. The crystals are transparent in the visible region having a lower optical cut-off at ∼406 nm and the band gap energies are estimated by the application of Kubelka–Munk algorithm. Thermal analysis by TG/DTA indicates the stability of the material. The scanning electron microscopy studies reveal the surface morphology of the as-grown crystal. Theoretical calculations were performed using Hartree–Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizability (β) values. 相似文献
205.
206.
A solvent-free mechanochemical route for the preparation of poly(2,5-dimethoxyaniline) hydrochloride nanostructures is developed
and reported in the article. High conductivity, good crystallinity, and nanostructured morphology are observed for the prepared
polymer. This polymeric powder is utilized as a cathode material in hybrid supercapacitor and its electrochemical performance
is evaluated and discussed in this short report. The maximum specific capacitance of the poly(2,5-dimethoxyaniline) hydrochloride/activated
carbon hybrid supercapacitor is found to be 125 F g−1 at 1 mA cm−2 current density. The cell delivers a specific energy as high as 50 Wh kg−1 at a specific power of 97 W kg−1 and also exhibits an excellent cycle performance with more than 99% coulombic efficiency and the maintenance of 85% of its
initial capacitance after 1,000 cycles. 相似文献
207.
Extending the problem of determining Ramsey numbers Erdős and Rogers introduced the following function. For given integers
2 ≤ s < t let f
s,t
(n) = min{max{|S|: S ⊆ V (H) and H[S] contains no K
s
}}, where the minimum is taken over all K
t
-free graphs H of order n. This function attracted a considerable amount of attention but despite that, the gap between the lower and upper bounds
is still fairly wide. For example, when t=s+1, the best bounds have been of the form Ω(n
1/2+o(1)) ≤ f
s,s+1(n) ≤ O(n
1−ɛ(s)), where ɛ(s) tends to zero as s tends to infinity. In this paper we improve the upper bound by showing that f
s,s+1(n) ≤ O(n
2/3). Moreover, we show that for every ɛ > 0 and sufficiently large integers 1 ≪ k ≪ s, Ω(n
1/2−ɛ
) ≤ f
s,s+k
(n) ≤ O(n
1/2+ɛ
. In addition, we also discuss some connections between the function f
s,t
and vertex Folkman numbers. 相似文献
208.
209.
The effect of the chemical composition of the reacting mixture (RM) on the amount of zeolite ZSM-5 and other crystalline phases and the amorphous phase as well in the obtained preparations was investigated. Ethylenediamine (ED) served as a templating agent. The quantitative estimation of the phase composition was made on the ground of X-ray diffraction measurements. Zeolite ZSM-5 of maximum phase purity of 96%, contaminated mainly with quartz and mordenite, was obtained. 相似文献