共查询到20条相似文献,搜索用时 15 毫秒
1.
Yu-Feng Hu Xian-Ming Zhang Chuan-Wei Jin Xiao-Ming Peng 《Journal of solution chemistry》2010,39(12):1828-1844
Viscosities were measured for the ternary aqueous systems NaCl–mannitol(C6H14O6)–H2O, NaBr–mannitol–H2O, KCl–mannitol–H2O, KCl–glycine(NH2CH2COOH)–H2O, KCl–CdCl2–H2O, and their binary subsystems NaCl–H2O, KCl–H2O, NaBr–H2O, CdCl2–H2O, mannitol–H2O, and glycine–H2O at 298.15 K. A powerful new approach is presented for theoretical modeling of the viscosity of multicomponent solutions
in terms of the properties of their binary solutions. In this modeling, the semi-ideal solution theory was used to associate
the solvation structure formed by each ion and its first solvation shell in a binary solution with the solvation structure
of the same ion and its first solvation shell in multicomponent solutions. Then, the novel mechanism proposed by Omta et al.
(Science, 301:347–349, 2003) for the effect of a single electrolyte on the viscosity of water was extended to describe the influence of solute mixtures
on the viscosity of water, including electrolyte mixtures, nonelectrolyte mixtures, and mixtures of electrolytes with nonelectrolytes.
The established simple equation was verified by comparison with measured viscosities and viscosities reported in literature.
The agreements are very impressive. This formulation provides a powerful new approach for modeling this transport property
in solutions. It can stimulate further research in establishing a dynamical analogue to that formulated for the thermodynamics
of multicomponent solutions. It is also very important for the study of hydration of ions. 相似文献
2.
Neoflavone β-D-glucopyranosides, β-D-galactopyranosides, β-D-xylopyranosides, and α-D-arabinopyranosides were synthesized
by Michael condensation of potassium salts of 7-hydroxy-4-arylcoumarins with acetobromosugars followed by deacetylation of
the resulting peracetates.
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Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 546–550, November–December, 2005. 相似文献
3.
The lactone 20R-25-norcycloartan-3β,6α,16β-triol-20,24-olide was synthesized from cyclosiversigenin.
Presented at the 1st International Symposium on Edible Plant Resources and the Bioactive Ingredients, Xinjiang, China, July
25–27, 2008.
Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 324–327, May–June, 2009. 相似文献
4.
L. A. Yakovishin V. I. Grishkovets N. N. Arnautov V. Ya. Chirva 《Chemistry of Natural Compounds》1999,35(5):587-588
Triterpene glycosides from leaves of canary ivyHedera canariensis Willd. were previously isolated and characterized [1–4]. The glycosidic composition of the plant stems is reported in the
present article.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 676–678, September–October, 1999. 相似文献
5.
I. V. Nagorichna A. A. Tkachuk M. M. Garazd Ya. L. Garazd V. P. Khilya 《Chemistry of Natural Compounds》2009,45(2):152-157
Spiropyranobenzopyrandiones were prepared, reduced, and dehydrated to form spirosubstituted pyranocoumarins.
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 135–139, March–April, 2009. 相似文献
6.
Another new cardenolide glycoside has been isolated from the plantCheiranthus allioni Hort., and has been named glucocheiranthoside. Its chemical structure has been established as 3β-(4′-O-β-D-glucopyranosyl-β-D-gulmoethylpyranosyloxy)-14-hydroxy-19-oxo-5β,14β-card-20(22)-enolide.
State Scientific Center for Drugs, Ukraine, 310085, Kharkov, USSR. ul. Astronomicheskaya, 33. Translated from Khimiya Prirodnykh
Soedinenii, No. 2, pp. 269–271, March–April, 1994. 相似文献
7.
V. N. Vasilets L. A. Demidenko E. A. Krasnov E. V. Ermilova N. N. Red'kina 《Chemistry of Natural Compounds》1988,24(6):748-748
Tomsk Medical Institute. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 875–876, November–December, 1988. 相似文献
8.
I. P. Dubovik M. M. Garazd V. I. Vinogradova V. P. Khilya 《Chemistry of Natural Compounds》2006,42(2):133-137
N-Acetyl derivatives of cytisine modified by coumarins were synthesized.
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Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 110–113, March–April, 2006. 相似文献
9.
A novel method using liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry in the
negative selected ion monitoring mode has been developed and validated for rapid simultaneous determination of triptolide
and tripdiolide in the extract of Tripterygium wilfordii Hook. f. The molecular ions m/z [M–H]− 359 and 375 were selected for the quantification in selected ion monitoring mode for triptolide and tripdiolide. Standard
calibration curve was linear over the concentration range of 0.12–24 and 0.15–30 μg mL−1 for triptolide and tripdiolide. The relative standard deviations of intra- and inter-day were in the range of 4.7–9.9 and
8.9–12.6%. The average recoveries were between 96.4 and 104.6%. The limits of quantitation were 2.0 × 10−3 and 2.5 × 10−3 μg mL−1 for triptolide and tripdiolide. 相似文献
10.
U. A. Baltaev 《Chemistry of Natural Compounds》1991,27(6):712-713
A new ecdysteroid (rhapisterone B) has been isolated from the seeds ofRhaponticum cathamoides (Willd.) Iljin. (familyCompositae). It has been shown that it is 2β, 3β, 11α, 14α, 20R, 24ξ-hexahydroxy-5β-cholest-7-en-6-one.
Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii,
No. 6, pp. 806–808, November–December, 1991. 相似文献
11.
A. É. Timbekova M. F. Larin M. R. Yagudaev N. K. Abubakirov 《Chemistry of Natural Compounds》1989,25(5):573-576
A new triterpene glycoside — medicoside H — has been isolated from the roots ofMedicago sativa L. (Fabaceae), and on the basis of chemical transformations and spectral characteristics its structure has been established
as medicagenic acid 3-O-β-D-glucopyranoside 28-O-[O-α-L-rhamnopyronosyl-(1 → 2)-β-L-arabino-pyranoside].
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, No. 5, pp. 673–677, September–October, 1989. 相似文献
12.
Jerzy Jurczyk Rafał Sitko Beata Zawisza Franciszek Buhl Ewa Malicka 《Mikrochimica acta》1999,132(1):41-47
A simple and quick method of durable samples preparation by the thin layer method through direct digesting of the analysed
material on the substrate has been presented. Four- and three-component mono- and polycrystals have been analysed. Standards
have been used in calibration containing: Cr, Co, Ni, Cu, Zn, Ga, Se, Sb, Yb. To improve the correlation between the concentration
and the fluorescent radiation models of mathematical corrections have additionally been used: multiple linear regression,
Lucas-Tooth-Pyne model (L. T. P.) and de Jongh model (d. J.).
Statistical parameters: detection limits for 0.5 mg samples: Cr–0.041%, Co–0.034%, Ni–0.042%, Cu–0.053%, Zn–0.054%, Ga–0.057%,
Se–0.057%, Sb–0.113%, Yb–0.077%. Correlation coefficients: simple regression 0.9946–0.9997, multiple regression 0.9974–1.0000,
L. T. P. 0.9993–1.0000, d. J. 0.9995–1.0000.
Received August, 1, 1998. Revision March 25, 1999. 相似文献
13.
M. V. Telezhenetskaya A. L. D'yakonov S. Yu. Yunusov 《Chemistry of Natural Compounds》1989,25(6):729-729
Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, Vol. 6, pp. 857–858, November–December, 1989. 相似文献
14.
Cycloadsurgenin, 20R,24 S-epoxycycloartan-6α,25-diol-3,16-dione, was partially synthesized in four steps from cyclosieversigenin. Side products with the structures 17E,24S-cycloart-17-en-6α,24,25-triol-3,16-dione and 17Z,24 S-cycloart-17-en-6α,24,25-triol-3,16-dione were obtained in addition to the desired product.
Presented at the 1st International Symposim on Edible Plant Resources and the Bioactive Ingredients, Xinjiang, China, July
25–27, 2008.
Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 591–595, November–December, 2008. 相似文献
15.
Summary. Parameters of the formalism [1–6] describing spin crossover in the solid state have been defined via molecular potentials in model systems of neutral and ionic complexes. In the first instance Lennard-Jones and electric dipole–dipole potentials have been used whereas in ionic systems Lennard-Jones and electric point-charge potentials have been used. Electric dipole–dipole interaction of neutral complexes brings about
a positive excess energy controlled by the difference of electric dipole moments of HS and LS molecules. Differences of the
order of Δμ = 1–2 D cause an abrupt spin crossover in systems with T1/2 = 100–150 K. Magnetic coupling contributes both to the excess energy and excess entropy, however the overall effect is equivalent
to a modest positive excess energy. Ionic systems in the absence of specific interactions are characterised by very small
excess energies corresponding to practically linear van’t Hoff plots. Detectable positive and negative excess energies in these systems may arise from interactions of ligands belonging
to neighbouring complexes. The HOMO–LUMO overlap in HS–LS pairs can bring about a nontrivial variation of the shape of transition
curves. Examples of regression analysis of experimental transition curves in terms of molecular potentials are given. 相似文献
16.
Ahmed Galal Soher A. Darwish Rasha A. Ahmed 《Journal of Solid State Electrochemistry》2007,11(4):531-542
Conducting polymers were modified with Cu-phthalocyanine or Co-phthalocyanine embedded in a sol–gel matrix. The resulting
films were characterized using electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy and scanning
electron microscopy. Electrochemical impedance spectroscopy data showed that the application of the sol–gel layer to the conductive
polymer caused a noticeable increase in the impedance of the film across the frequency ranges studied. The hydrophobic character
of the film was greatly influenced by the sol–gel and caused an increase in its capacitance. A modified ‘Randles’ equivalent
cell was used to correlate the electrochemical parameters of the films. Elemental analysis and infrared data confirmed the
presence of the phthalocyanine moieties in the film and the empirical formula of the film was estimated. The surface morphology
of the sol–gel-modified conducting polymer was distinctly amorphous compared to the poly(3-methyl thiophene). 相似文献
17.
U. T. Teshebaeva A. N. Sultankhodzhaev A. A. Nishanov 《Chemistry of Natural Compounds》1999,35(6):659-660
A new alkaloid called akiramidine is isolated from the aerial part ofAconitum kirinense. The structure 6β,14α,16β-trimethoxy-1α,4β,8β-trihydroxy-N-ethylaconitane is proposed based on spectral data and confirmed
by chemical transformation from akiramine.
Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 774–776, November–December, 1999. 相似文献
18.
M. V. Veselovskaya A. S. Ogorodniichuk M. M. Garazd Ya. L. Garazd V. P. Khilya 《Chemistry of Natural Compounds》2005,41(5):516-522
Angular dihydropyranocoumarins containing natural and synthetic amino acids and dipeptides were synthesized using activated
esters.
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Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 422–427, September–October, 2005. 相似文献
19.
Institute of the Ecology of the Volga Basin, Russian Academy of Sciences, Tol'yatti. Translated from Khimiya Prirodnykh Soedinenii,
No. 6, pp. 850–852, November–December, 1991. 相似文献
20.
Ya. L. Garazd M. M. Garazd V. A. Turov V. P. Khilya 《Chemistry of Natural Compounds》2006,42(6):652-655
Cyclohexyldihydroxanthyletin derivatives with S and N in place of the exocyclic O atom were synthesized. The structures of
the products were proved by NMR correlation spectroscopy.
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Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 531–533, November–December, 2006. 相似文献