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排序方式: 共有71条查询结果,搜索用时 31 毫秒
11.
Zusammenfassung Das Pektin ist als Schutzkolloid zur Stabilisierung der Farbe des Kupferkomplexes ausgezeichnet anwendbar. Die Fehlergrenzen bei der Bestimmung des Kupfers in wäßerigen und in Serum-Lösungen sind gering. Die Unterschiede zwischen den ermittelten Extinktionswerten in wäßerigen und Serum-Lösungen sind zwar signifikant, aber doch so gering, daß sie vernachlässigt werden können. Das beschriebene Verfahren ist empfindlich, einfach und auch serienweise leicht mit großer Genauigkeit ausführbar.
Summary Pectin can be used to good advantage as a protective colloid for stabilizing the color of the copper complex. The limits of error are small in the determination of copper in aqueous and serum solutions. The differences between the observed extinction values in aqueous and serum solution are admittedly significant but they are so slight that they may be neglected.The procedure described here is sensitive, simple, and it may easily be conducted with high accuracy with a series of samples.
Résumé La pectine est un excellent colloïde protecteur pour la stabilisation de la couleur du complexe du cuivre. Dans des solutions aqueuses ou dans le sérum des limites d'erreur du dosage du cuivre sont très faibles. Les différences qui existent entre les valeurs déterminées par extinction en solutions aqueuses ou dans le sérum sont à peine significatives; de toutes façons elles sont si faibles qu'elles peuvent être négligées. La technique décrite est sensible, simple et aisément utilisable dans les dosages de séries avec grande précision.相似文献
12.
F. Taneri T. Güneri Z. Aigner O. Berkesi M. Kata 《Journal of Thermal Analysis and Calorimetry》2004,76(2):471-479
γ-Cyclodextrin and dimethyl-β-cyclodextrin were used as solubilizing agents for a very poorly water-soluble drug, an imidazole
derivative antifungal agent, clotrimazole; with the aim of improving the physicochemical properties of the drug. Solid products
were prepared by physical mixing, kneading, precipitation and spray-drying methods in 1:1 and 1:2 drug:cyclodextrin molar
ratios. Drug interactions were studied by thermoanalytical methods such as DSC, DTA, TG and DTG, X-ray diffractometry and
Fourier transformation-infrared spectroscopy. The results demonstrated the formation of inclusion complexes in some products.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Filiz Taneri Tamer Güneri Zoltán Zoltán Michael Kata 《Journal of inclusion phenomena and macrocyclic chemistry》2003,47(1-2):15-23
The effects of hydroxypropyl-β-cyclodextrin and methyl-β-cyclodextrin on the solubility of ketoconazole were studied. Products were prepared by physical mixing, kneading and spray-drying methods in four molecular ratios. Kneaded products in a ratio of drug: cyclodextrin (1:2) and spray-dried products showed the highest dissolution rate. Phase solubility diagrams of ketoconazole with these cyclodextrins at 25,°C in water and simulated intestinal medium were constructed. A solubility diagram of AL type was obtained with hydroxypropyl-β-cyclodextrin, and AP type with methyl-β-cyclodextrin. The complexes were characterized by thermal methods (DSC, TG, DTG and DTA). Multicomponent systems were prepared with tartaric acid. The effects of water-soluble polymers, e.g., polyvinylpyrrolidone, on the aqueous solubility of ketoconazole were investigated. The particle size of ketoconazole (70 ~ μm) is reduced to 12 μm by the preparation of spray-dried products. As the solubilty in water increased, the partition coefficient, surface tension and wetting angle values decreased. Ketoconazole needed more energy for dissolution compared to the products. In order to examine complex formation thermal methods were used. 相似文献
14.
A Nexus between Theory and Experiment: Non‐Empirical Quantum Mechanical Computational Methodology Applied to Cucurbit[n]uril⋅Guest Binding Interactions
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Jiří Hostaš Dr. David Sigwalt Marina Šekutor Haresh Ajani Dr. Matúš Dubecký Prof. Jan Řezáč Dr. Peter Y. Zavalij Dr. Liping Cao Christian Wohlschlager Prof. Kata Mlinarić‐Majerski Prof. Lyle Isaacs Prof. Robert Glaser Prof. Pavel Hobza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17226-17238
A training set of eleven X‐ray structures determined for biomimetic complexes between cucurbit[n]uril (CB[7 or 8]) hosts and adamantane‐/diamantane ammonium/aminium guests were studied with DFT‐D3 quantum mechanical computational methods to afford ΔGcalcd binding energies. A novel feature of this work is that the fidelity of the BLYP‐D3/def2‐TZVPP choice of DFT functional was proven by comparison with more accurate methods. For the first time, the CB[n] ? guest complex binding energy subcomponents [for example, ΔEdispersion, ΔEelectrostatic, ΔGsolvation, binding entropy (?TΔS), and induced fit Edeformation(host), Edeformation(guest)] were calculated. Only a few weeks of computation time per complex were required by using this protocol. The deformation (stiffness) and solvation properties (with emphasis on cavity desolvation) of cucurbit[n]uril (n=5, 6, 7, 8) isolated host molecules were also explored by means of the DFT‐D3 method. A high ρ2=0.84 correlation coefficient between ΔGexptl and ΔGcalcd was achieved without any scaling of the calculated terms (at 298 K). This linear dependence was utilized for ΔGcalcd predictions of new complexes. The nature of binding, including the role of high energy water molecules, was also studied. The utility of introduction of tethered [‐(CH2)nNH3]+ amino loops attached to N,N‐dimethyl‐adamantane‐1‐amine and N,N,N′,N′‐tetramethyl diamantane‐4,9‐diamine skeletons (both from an experimental and a theoretical perspective) is presented here as a promising tool for the achievement of new ultra‐high binding guests to CB[7] hosts. Predictions of not yet measured equilibrium constants are presented herein. 相似文献
15.
New host molecules for anions, adamantane, and alkyl urea derivatives substituted by naphthalene chromophores, were synthesized. Their binding with F−, Cl−, Br−, OAc−, HSO4−, NO3−, and H2PO4− was investigated by UV-vis, fluorescence and NMR spectroscopy. The anion binding ability of adamantyl bisurea derivatives was compared with the analogous host molecules, wherein the urea moieties are separated by flexible alkyl linkers of the same length, and adamantane monourea derivative. The host molecules show the highest selectivity toward F− and H2PO4−. The binding stoichiometry and the values of the association constants depend on the basicity of anions, availability of H-bonding sites, preorganization, and rigidity of the hosts, as well as solvent polarity and H-bonding availability. Rigid adamantane receptors, compared to flexible analogues show increased selectivity for H2PO4−, whereas binding of OAc− is better with flexible receptors. The binding of OAc− and H2PO4− was investigated by microcalorimetry. The stoichiometries and the stability constants of the corresponding complexes obtained by this method were in good agreement compared to those determined by UV-vis titrations. In both cases the enthalpic contribution to the overall complex stability was predominant. 相似文献
16.
Marija Aleškovi? Kata Mlinari?-Majerski Krešimir Mol?anov Manoj K. Kesharwani 《Tetrahedron》2010,66(9):1689-8746
Adamantane-dipyrromethane (AdD) receptors [di(pyrrole-2-yl)methyladamantane (1), 2,2-di(pyrrole-2-yl)adamantane (2), 1,3-bis[di(pyrrole-2-yl)methyl]adamantane (3), 2,2,6,6-tetra(pyrrole-2-yl)adamantane (4)] form complexes with F−, Cl−, Br−, AcO−, NO3−, HSO4−, and H2PO4−. The association constants of the complexes were determined by 1H NMR titrations, whereas the geometries of complexes 1·F− (2:1), 2·F− (2:1), 2·Cl− (2:1), 2·AcO− (2:1), and 4·F− (1:1) were determined by X-ray structural analysis. The most stable complexes are of 2:1 stoichiometry with F− and AcO−. The stability constants are in accordance with the anion basicity and the ability of AdD receptors to place the hydrogen bonding donor groups in a tetrahedral fashion around anions. The binding energies of the complexes between receptors 1-4 and F− anion are calculated using quantum chemical methods. The calculated results show that the solvent polarity is important for the complexation of fluoride ion with AdD receptors 1-4. 相似文献
17.
L. I. Kursheva O. N. Kataéva I. A. Litvinov V. A. Naumov 《Journal of Structural Chemistry》1992,33(1):123-127
A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Science Center, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 145–150, January–February, 1992. 相似文献
18.
The aim of this study was to compare the adsorption of various organic drugs and a well-studied surfactant. The organic drugs
used were promethazine chloride [10-(2-dimethylammonium) propylfenothiazine chloride] and buformin hydrochloride (1-butylbiguanidine
chloride). The surfactant was benzalkonium chloride (N-tridecyl-N-benzyl-N,N-dimethylammonium chloride). Different amounts of drug solutions were added to montmorillonite suspensions, either separately
(simple system) or in combination (competitive system) under the same conditions, and the organocomplexes formed were investigated.
The organic molecule with the short alkyl chain adsorbed to yield monolayer coverage, whereas the aromatic molecule and the
surfactant formed a pseudotrimolecular arrangement. In the competitive system, the larger organic molecules (having the same
charge) displaced the smaller one from the interlayer space. The intercalation of molecules in the interlayer space was investigated
by X-ray diffraction measurements.
Received: 30 November 2000 Revised: 20 December 2001 Accepted: 26 October 2001 相似文献
19.
Koppenburg P Abe K Abe K Abe T Adachi I Aihara H Akatsu M Asano Y Aulchenko V Aushev T Bakich AM Ban Y Bay A Bitenc U Bizjak I Bondar A Bozek A Bracko M Browder TE Chang P Chao Y Chen KF Cheon BG Choi Y Chuvikov A Cole S Danilov M Dash M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fang F Fratina S Gabyshev N Garmash A Gershon T Gokhroo G Golob B Haba J Hayashii H Hazumi M Higuchi T Hinz L Hokuue T Hoshi Y Hou WS Hsiung YB Iijima T Inami K Ishikawa A Itoh R Iwasaki H Iwasaki M Kang JH Kang JS 《Physical review letters》2004,93(6):061803
We report a fully inclusive measurement of the flavor changing neutral current decay b --> sgamma in the energy range 1.8 GeV < or = E*gamma < or = 2.8 GeV, covering 95% of the total spectrum. Using 140 fb(-1), we obtain B(b --> sgamma) = (3.55+/-0.32(+0.30+0.11)(-0.31-0.07)) x 10(-4), where the errors are statistical, systematic, and from theory corrections. We also measure the first and second moments of the photon energy spectrum above 1.8 GeV and obtain (Egamma) = 2.292+/-0.026+/-0.034 GeV and (E2gamma) - (Egamma)2 = 0.0305+/-0.0074+/-0.0063 GeV2, where the errors are statistical and systematic. 相似文献
20.
Gergely B. Cserép Kata N. Enyedi Prof. Attila Demeter Prof. Gábor Mező Dr. Péter Kele 《化学:亚洲杂志》2013,8(2):494-502
A set of new azide‐ and alkyne‐bearing lepidinium‐based fluorophores were synthesized for bioorthogonal labeling schemes. These fluorescent dyes all show large Stokes‐shifts with emission maxima in the near‐infrared (NIR) region of the electromagnetic spectrum. The applicability of these dyes in the construction of energy‐transfer systems was tested using one of these new fluorescent tags and daunomycin (Dau), an anticancer drug with fluorescent features. These daunomycin conjugates are the very first examples of fluorescently modulated constructs of this anticancer agent. The dually labeled architectures proved that the applied fluorescent dye can be utilized as an efficient quencher for daunomycin. Enzymatic cleavage of a dually labeled enzyme substrate resulted in full recovery of the fluorescence of daunomycin. Such fluorescently modulated Dau conjugates can provide useful information for the mechanism of action of Dau‐regulated cell death processes. 相似文献