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71.
Kunze C 《Physical review. B, Condensed matter》1993,48(19):14338-14346
72.
Density gradient electrophoresis permits the separation of cell types according to surface charge density with high resolution. Any source of flow compromises the resolving power of density gradient electrophoresis. Although procedures have been devised to successfully counteract electroosmotic and convective flows, the final collection of separands requires that they be pumped out of the electrophoresis column. Experiments were therefore designed to test the hypothesis that this flow could also be eliminated by trapping the separated bands in a gel, from which they could be collected by slicing the gel cylinder. Glutaraldehyde-fixed rat and rabbit erythrocytes were used as test particles in a phosphate-buffered isotonic Ficoll-sucrose density gradient in a 2.2 cm diameter, thermostated vertical glass column that could be opened at both ends. Two types of agarose were used as gel polymers: Electrophoresis grade agarose (J.T. Baker Chemical Co.) at final concentrations of 0.1 to 0.25% and SeaPrep ultralow gelling agarose (Marine Colloids Div., FMC Corp.) at a final concentration of 1.0%. Electrophoretic separability of the test particles and fluid stability were tested independently at 55 degrees C and 32 degrees C at which the two agaroses were, respectively, liquid. The experiments demonstrated that the higher temperatures required and the presence of agarose compromised neither the stability of the density gradient nor the migration properties of the cells, and cells can be separated in a sol at a temperature that is compatible with cell viability. 相似文献
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74.
As strong nucleophiles, phosphorus ylids easily attack heteroallenes. The addition of isopropylidene triphenylphosphorane to carbon disulfide yields the zwitterionic adduct Ph3PCMe2CS2?, which reacts to bis(isopropylidene)-1,2,4-trithiolane by thermal or, coordinated to transition metals, photochemical activation according to a cycloaddition mechanism. By reaction of the betaine with manganese and rhenium carbonyl halides under exclusion of light, stable monomeric and dimeric fac-tricarbonyl complexes with the composition (CO)3M?(X)S2CCMe2PPh3 (M = Mn, Re; X = Cl, Br) are obtained which are distinguished by their spectra (IR, NMR, UV). The monomeric bromomanganese and -rhenium complexes are isomorphous and crystallize in the space group P2frcase1/c (monoclinic, Z = 4). 相似文献
75.
H. Procter Smith H. Rubricius H. Kunze H. Wdowiszewski W. Heike und J. J. Boyle 《Fresenius' Journal of Analytical Chemistry》1913,52(3-4):223-226
Ohne Zusammenfassung 相似文献
76.
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78.
Rachid S Krug D Kunze B Kochems I Scharfe M Zabriskie TM Blöcker H Müller R 《Chemistry & biology》2006,13(6):667-681
The jaspamide/chondramide family of depsipeptides are mixed PKS/NRPS natural products isolated from marine sponges and a terrestrial myxobacterium that potently affect the function of the actin cytoskeleton. As a first step to improve production in heterologous host cells and permit genetic approaches to novel analogs, we have cloned and characterized the chondramide biosynthetic genes from the myxobacterium Chondromyces crocatus Cm c5. In addition to the expected PKS and NRPS genes, the cluster encodes a rare tyrosine aminomutase for beta-tyrosine formation and a previously unknown tryptophan-2-halogenase. Conditions for gene transfer into C. crocatus Cm c5 were developed, and inactivation of several genes corroborated their proposed function and served to define the boundaries of the cluster. Biochemical characterization of the final NRPS adenylation domain confirmed the direct activation of beta-tyrosine, and fluorinated chondramides were produced through precursor-directed biosynthesis. 相似文献
79.
The photopolymerization of a commercial sheet material as used in the dental laboratory was investigated by using the photocalorimeter DSC7/DPA7 (Perkin-Elmer). Using normal reaction conditions (light wavelength 400 nm, light intensity 1 mW cm–2 and sample thickness 2.5 mm), the curing was completed within few min. The reaction rate was nearly independent on the light wavelength in the range between =300 and 380 nm, but decreased distinctively at longer wavelengths. After desmearing the DSC curves, the dependence of the reaction rate on light intensity and sample thickness could be described in very good approximation by an equation derived by Tryson [1]. Comparable with pure acrylates or methacrylates, a pronounced dark reaction was found after interruption of the illumination.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
80.
Hsi WC Kunde GJ Pochodzalla J Lynch WG Tsang MB Begemann-Blaich ML Bowman DR Charity RJ Cosmo F Ferrero A Gelbke CK Glasmacher T Hofmann T Imme G Iori I Hubele J Kempter J Kreutz P Kunze WD Lindenstruth V Lisa MA Lynen U Mang M Moroni A Müller WF Neumann M Ocker B Ogilvie CA Peaslee GF Raciti G Rosenberger F Sann H Scardaoni R Schüttauf A Schwarz C Seidel W Serfling V Sobotka LG Stuttge L Tomasevic S Trautmann W Tucholski A Williams C Wörner A Zwieglinski B 《Physical review letters》1994,73(25):3367-3370