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71.
Mag. pharm. Dr. Gerhard Buchbauer Günther W. Hana Heinrich Koch 《Monatshefte für Chemie / Chemical Monthly》1976,107(2):387-394
An improved synthesis of the title compound (1) is described. The catalytical action of variousLewis acids on the sterically hinderedDiels-Alder reaction of mesityl oxide with cyclopentadiene has been investigated. The mixture ofendo- andexo-isomers of the unsaturated intermediate2 yielded pure1 on hydrogenation and isomerization by sodium methoxide. The proof of theexo-configuration of the acetyl group has been achieved by mass spectra and 100 MHz1H-NMR spectra.
Herrn Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet. 相似文献
Herrn Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet. 相似文献
72.
Electrothermal atomisation of mercury in the presence of thiols. Sample stabilisation during the drying step is important for the determination of mercury by electrothermal a.a.s. Addition of complexing agents with thiol groups makes possible the analysis of pure aqueous solutions. Mercury can be determined at concentrations down to 5 × 10-6% with a reproducibility of 2–10%. Small amounts of acids and salts depress the efficiency of stabilisation, so that separation becomes necessary. The use of a selective ion-exchanger with thiol groups solves the problems of sample storage, separation and stabilisation. The enrichment enhances the sensitivity by two orders of magnitude. Determinations of 2–20 ppb Hg in water, 0.2–2 M HC1 and 0.2–1 M NaCl are reported. 相似文献
73.
The stability of the cytostatics, ftorafur and fluorouracil injections, was studied in dependence on irradiation with UV light and on the medium temperature and pH. In the first stage of the thermal and photochemical decomposition of ftorafur, tetrahydrofuran dissociated from position N1 in the pyrimidine ring and 5-fluorouracil was formed. In the second stage of the thermal and photochemical decomposition of ftorafur, the pyrimidine ring opened between N3 and C4 and between C6 and N1, with formation of urea. Ftorafur, fluorouracil, and urea were determined using thin-layer chromatography and spectrophotometry in the UV and visible region. 相似文献
74.
Refat MS Sadeek SA Khater HM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(3):778-788
The rapid interaction between o-tolidine and p-toluidine (pi-donors) with the pi-acceptors, e.g., 3,5-dinitrobenzoic acid (DNB) and 2,6-dichloroquinone-4-chloroimide (DCQ) results in the formation of 1:1 charge-transfer complexes as the final products, [(o-tolidine) (acceptor)] and [(p-toluidine) (acceptor)]. The final products of the reactions have been isolated and characterized using FTIR, 1HNMR spectroscopy and elemental analysis as well as photometric titration. The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method. 相似文献
75.
76.
77.
Pavić Kristina Rajić Zrinka Michnová Hana Jampílek Josef Perković Ivana Zorc Branka 《Molecular diversity》2019,23(3):657-667
Molecular Diversity - Here, we describe design and synthesis of twelve novel compounds bearing primaquine motif and hydroxy- or halogenamine linked by an urea or bis-urea spacer. Preparation of... 相似文献
78.
Hana Robson Marsden Nina A. Elbers Paul H. H. Bomans Dr. Nico A. J. M. Sommerdijk Dr. Alexander Kros Dr. 《Angewandte Chemie (International ed. in English)》2009,48(13):2330-2333
Let's get together : A minimal model system was developed to mimic the SNARE‐protein‐mediated fusion of biological membranes (see picture). Fusion between two populations of liposomes is controlled by a pair of complementary lipidated oligopeptides that form noncovalent coiled‐coil complexes and thereby force the membranes into close proximity to promote fusion. The model system displays the key characteristics of in vivo fusion events.
79.
Eduard Feireisl Hana Petzeltová Elisabetta Rocca 《Mathematical Methods in the Applied Sciences》2009,32(11):1345-1369
We prove the existence of weak solutions for a 3D phase change model introduced by Michel Frémond in (Non‐smooth Thermomechanics. Springer: Berlin, 2002) showing, via a priori estimates, the weak sequential stability property in the sense already used by the first author in (Comput. Math. Appl. 2007; 53 :461–490). The result follows by passing to the limit in an approximate problem obtained adding a superlinear part (in terms of the gradient of the temperature) in the heat flux law. We first prove well posedness for this last problem and then—using proper a priori estimates—we pass to the limit showing that the total energy is conserved during the evolution process and proving the non‐negativity of the entropy production rate in a suitable sense. Finally, these weak solutions turn out to be the classical solution to the original Frémond's model provided all quantities in question are smooth enough. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
80.
Vráblíková H McEvoy M Solhaug KA Barták M Gauslaa Y 《Journal of photochemistry and photobiology. B, Biology》2006,83(2):151-162
Seasonal variation in maximal photochemical quantum yield (F(V)/F(M)) of photosystem II (PS II), light adapted quantum yield (Phi(II)) of PS II, non-photochemical quenching (NPQ), contents of chlorophylls, and xanthophyll cycle pigments (VAZ) was studied in Xanthoria parietina repeatedly sampled in one location in S Norway during one year. The seasonal course in the susceptibility to photoinhibition was evaluated as high light-induced changes (1,800 micromol photons m(-2) s(-1) for 24h) in F(V)/F(M), Phi(II), and NPQ, measured as the ability to recover after 2 and 20 h at low light in control thalli with a natural cortical parietin screen, and in thalli from which parietin had been removed prior to high light exposures. F(V)/F(M), Phi(II), chlorophyll content, and the conversion state of VAZ (DEPS) reached minimum in spring. At the same time, yearly maxima of VAZ content and NPQ were recorded. Thereafter, F(V)/F(M), Phi(II), and chlorophyll content increased gradually, reaching maximum values in late autumn. DEPS peaked already in summer. Similarly, VAZ and NPQ decreased from early summer until winter. All data show that the X. parietina photobiont acclimates to seasonal changes in solar radiation, consistent with the lichen's preference for well-lit habitats. However, a comparison with a study of seasonal acclimation in the X. parietina mycobiont shows that in order to understand the seasonal photobiont acclimation, one has to consider the seasonal variation in internal screening caused by the fungal regulation of the PAR-absorbing parietin. A joint effort of both bionts seems to be required to avoid serious photoinhibition. 相似文献