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171.
A new family of potent aminoacid-type organogelators obtained via an easy and unexpensive way is described. We demonstrated that structural variations onto the side chains of the aminoacid derivatives allowed modulations of the gelation properties. The organogelators bearing a benzyl or an isopropyl group (compounds 1e, 2a, and 2c) are able to provide gelation of apolar solvents at very low concentration (0.2 wt %) and to form thermostable gels. 相似文献
172.
A linear expected-time algorithm for deriving all logical conclusions implied by a set of boolean inequalities 总被引:1,自引:0,他引:1
Consider a setR ofm binary relations on a set ofn boolean variables.R may imply a contradiction, the fixation of some variables at 0 or at 1 and/or the identification of some pairs of variables in direct or complemented form. An O(n) expected-time algorithm is given for the derivation of all such logical conclusions. Computational experiments with problems involving up to 2000 variables are reported on. The proposed algorithm is more than 100 times faster than previous methods whenn 100.On leave from Faculté Universitaire Catholique de Mons, Belgium. Written at CNRS, LAMSADE. Support of CNRS is gratefully acknowledged. 相似文献
173.
Novel capsules with high stability and controlled permeability by hierarchic templating 总被引:5,自引:0,他引:5
Dai Z Dähne L Möhwald H Tiersch B 《Angewandte Chemie (International ed. in English)》2002,41(21):4019-4022
174.
Über Thio-, Selenido- und Telluridogermanate (III): Zur Kenntnis von K6Ge2S6, K6Ge2Se6 und Na6Ge2Te6
On Thio-, Selenido-, and Telluridogermanates (III): K6Ge2S6, K6Ge2Se6, and Na6Ge2Te6 The new compounds K6Ge2S6 and K6Ge2Se6 crystallize in the monoclinic system, space group C2/m (No 12); lattice constants see “Inhaltsübersicht”. The compounds are isotypic and form the K6Si2Te6 structure. Na6Ge2Te6 crystallizes in the K6Sn2Te6 structure, monoclinic, space group P21/c (No 14); lattice constants see “Inhaltsübersicht”. 相似文献
175.
Helmut Görner Johannes Leitich Oskar E. Polansky Werner Riemer Ursula Ritter-Thomas Brigitte Schlamann 《Monatshefte für Chemie / Chemical Monthly》1980,111(1):309-329
The title compound,1, slowly decomposes in solution by autodixation, especially in daylight. The chemism of this photoinduced autoxidation has been investigated.Upon irradiation1 passes to the brick red isolable dienol2. The quantum yield is 0.3 at 313 nm in methanol. In solution an equilibrium is set up within several minutes between2 and the colorless deconjugated3. Unpolar or moderately polar solvents shift the equilibrium completely to3, whereas in highly polar solvents2 and3 coexist. In the dark the equilibrium12 (ca. 501 in methanol) is established very slowly.3 upon irradiation reacts further to dimer8.
2 instantaneously reacts with oxygen. With high oxygen concentrations, hydroperoxide9 is formed, with lower ones dehydrodimer10, inter alia.9 and10 may further form12, 14, and15. These reactions, together with ESR spectroscopy, point to a central role of the free radical13 both in the autoxidation and in the reaction1014.Basic catalysis sets up an equilibrium between1 and its dimer,17. The photoreaction12 has been investigated by sensitizing and quenching experiments.
34. Mitteilung:J. Bitter, J. Leitich, H. Partale, O. E. Polansky, W. Riemer, U, Ritter-Thomas, B. Schlamann undB. Stilkerieg, Chem. Ber., im Druck. 相似文献
176.
Brigitte Gutsche und Roland Herrmann 《Fresenius' Journal of Analytical Chemistry》1971,253(4):257-262
Zusammenfassung Der von früheren Untersuchungen her bekannte In-Brenner für den spezifischen Chlor(359,9 nm) und Brom-(327,7 nm)Nachweis wird in dieser Arbeit für den spezifischen Jod-Nachweis bei 409,9 nm benützt. Es wird gezeigt, daß man mit einem solchen Detektor in günstigen Fällen das Auflösungsvermögen eines GC verbessern kann. Nach vorangegangener Eichung sind Aussagen darüber möglich, wieviel Jod in den einzelnen GC-Fraktionen enthalten ist. Die Nachweisgrenzen des Verfahrens liegen zwischen 0,01–1,4 g Jod.
Unterstützt mit Mitteln der Deutschen Forschungsgemeinschaft. 相似文献
Iodine-specific detector for a gas chromatograph
The In-flame detector earlier applied to the specific chlorine (359.9 nm) and bromine (372.7 nm) analysis has now been employed for the iodine determination at 409.9 nm. It is shown that the resolution power of a GC column can be improved by such a specific detector. After calibration quantitative measurements of the iodine contents of the GC fractions are possible. The detection limits are 0.01–1.4 g of iodine.
Unterstützt mit Mitteln der Deutschen Forschungsgemeinschaft. 相似文献
177.
A plant enzyme - vellosimine reductase - has been isolated from cell suspension cultures. This new enzyme has been-purified (110-fold) and characterized. The reductase is a specific enzyme of the sarpagine pathway catalyzing the NADPH dependent conversion of vellosimine into 10-deoxysarpagine. The latter alkaloid is the immediate biogenetic precursor of sarpagine as shown by its high incorporation rate (86%) into sarpagine. 相似文献
178.
B3N3Me6Cr(CO)3 reacts with [AsPh4] [SnCl3] and [AsPh4] [GeCl3] in tetrahydrofuran to give [AsPh4]3[Cr(CO)3(SnCl3)3] and [AsPh4]3[Cr(CO)3(GeCl3)3], respectively. According to IR. and 13C-NMR.-data, the tricarbonylate anions possess a meridional configuration. The donor-acceptor properties of SnCl3? and GeCl3? in the anions [Cr(CO)3(ECl3)3]3? (E = Sn, Ge) are very similar. A similar synthesis of [AsPh4]3[Cr(CO)3(SnF3)3] was not successful. 相似文献
179.
Angelova A Angelov B Papahadjopoulos-Sternberg B Ollivon M Bourgaux C 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):4138-4143
Proteocubosomes are nanostructured open-nanochannel hierarchical fluid vehicles characterized by a cubic lattice periodicity of the lipid/protein supramolecular assembly (protein-loaded cubosomes). They are obtained here at very high hydration levels by a three-dimensional (3D) self-assembly process, which exploits a protein-directed 3D patterning and fragmentation to create a new, tertiary-level structural order of fluid lipid/water interfaces. Our freeze-fracture electron microscopy study reveals that the proteocubosome structures are built up by patterned assemblies of nanocubosomes, which comprise 3D nanoporous fracture surfaces throughout. Complex cubosomic architectures, involving arrays of nanodroplets (larger than 20 nm) inside the proteocubosome particles, are established at high resolution. The soft-matter hierarchical nanocompartment formations display internal aqueous pores belonging to the D-type lipid cubic lattice nanochannel system that is proven by synchrotron X-ray diffraction. The reported nanostructured fluid may give rise to novel applications in nanofluidic biomimetic devices, porous protein drug delivery vehicles, nanoscale enzymatic bioreactors, and protein-encapsulating fluid nanomaterials. 相似文献
180.
Brigitte Gutsche und Roland Herrmann 《Fresenius' Journal of Analytical Chemistry》1970,249(3):168-171
Zusammenfassung Der von früheren Untersuchungen her bekannte In-Brenner für den spezifischen Chlornachweis bei 359,9 nm wird in dieser Arbeit für den spezifischen Bromnachweis bei 372,7 nm benützt. Über Erfahrungen mit diesem Br-spezifischen Detektor hinsichtlich qualitativem und quantitativem Bromnachweis in den Fraktionen eines Gas-Chromatographen wird berichtet. Außerdem wird gezeigt, daß man mit einem solchen Detektor in günstigen Fällen das Auflösungsvermögen eines GC verbessern kann.
Diese Arbeit wurde mit Mitteln der Deutschen Forschungsgemeinschaft unterstützt. 相似文献
Specific detector for the identification of bromine after gas-chromatographic separation
The In-flame-detector earlier applied to the specific chlorine analysis at 359,9 nm has now been employed for bromine determinations at 372,7 nm. Qualitative and quantitative analyses in the fractions of a gas chromatograph are described. It is shown that the resolution power of a GC column can be improved by such an specific detector.
Diese Arbeit wurde mit Mitteln der Deutschen Forschungsgemeinschaft unterstützt. 相似文献