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951.
The photometric and fluorometric characteristics of the complex formed by 1,4-dihydroxyanthraquinone with Y(III) in 20–80% water-ethanol solution are described by the study of several variables. The stoichiometry and stability constant of the complex in the solution are 1:1 and log K = 4.57, respectively. The 1,4-dihydroxyanthraquinone-Y(III) solid complex has been prepared and studied by infrared spectroscopy and thermal analysis. The thermal behavior of this compound has been studied using thermogravimetry and differential scanning calorimetry techniques and the residue verified by X-ray diffraction. 相似文献
952.
The thermal decompositions of CuInSe2, LiInSe2 and LiInTe2 in vacuum at high temperatures were studied by using TG/DTG coupled with mass spectrometry. For CuInSe2, two steps were found to be significant. Up to 1000 °C Se2 and In2Se evaporate, followed later by Cu2Se. The Li-containing compounds show similar behaviour. However, Li+ was already detected during the first step. Obviously, Li2Se dissociates more readily than Cu2Se. No Cu+ species were detected up to the complete evaporation of CuInSe2. 相似文献
953.
The synthesis of [O9,24] [2.1.2.1]metacyclophane-9-ene and of its dehydrogenation products^the new pyrenocyclophanes , , , and , is described; their structures are discussed in connection with their 1H-NMR-spectra. 相似文献
954.
Mona Wells Michael Gösch Hauke Harms Jan Roelof van der Meer 《Mikrochimica acta》2005,151(3-4):209-216
This paper describes the development of an analytical technique for arsenic analyses that is based on genetically-modified
bioreporter bacteria bearing a gene encoding for the production of a green fluorescent protein (gfp). Upon exposure to arsenic
(in the aqueous form of arsenite), the bioreporter production of the fluorescent reporter molecule is monitored spectroscopically.
We compared the response measured as a function of time and concentration by steady-state fluorimetry (SSF) to that measured
by epi-fluorescent microscopy (EFM). SSF is a bulk technique; as such it inherently yields less information, whereas EFM monitors
the response of many individual cells simultaneously and data can be processed in terms of population averages or subpopulations.
For the bioreporter strain used here, as well as for the literature we cite, the two techniques exhibit similar performance
characteristics. The results presented here show that the EFM technique can compete with SSF and shows substantially more
promise for future improvement; it is a matter of research interest to develop optimized methods of EFM image analysis and
statistical data treatment. EFM is a conduit for understanding the dynamics of individual cell response vs. population response, which is not only a matter of research interest, but is also promising in the practical terms of developing
micro-scale analysis. 相似文献
955.
We employ extensive Monte Carlo and molecular-dynamics simulations to investigate the effective interactions between the centers of mass of dendritic macromolecules of variable flexibility and generation number. Two different models for the connectivity and steric interactions between the monomers are employed, the first one being purely entropic in nature and the second explicitly involving energetic interactions. We find that the effective potentials have a generic Gaussian shape, whose range and strength can be tuned via modifications in the generation number and flexibility of the spacers. We supplement our simulation analysis by a density-functional approach in which the connectivity between the monomers is approximated by an external confining potential that holds the monomer beads together. Using a simple density functional for the interactions between the monomers, we find semiquantitative agreement between theory and simulation. The implications of our findings for the interpretation of scattering data from concentrated dendrimer solutions are also discussed. 相似文献
956.
Joeng-Shein Chen Harald Berndt Günther T?lg 《Fresenius' Journal of Analytical Chemistry》1992,344(12):526-534
Summary Various possibilities for the determination of trace impurities in high-purity iron by atomic spectrometry were investigated in detail. For Ba, Bi, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti and V, flame AAS, furnace AAS and ICP-OES were firstly evaluated in terms of their power of detection. Detection limits in the g/g-range could be achieved by direct determination. For determination in the ng/g-range a removal of iron by a solvent extraction technique prior to the instrumental measurement was required. The power of detection of direct determination, and of combined procedures were compared with regard to routine applicability and a minimization of systematic errors. 相似文献
957.
958.
Starting from the natural neo-clerodane diterpenoid teubotrin (1) several neo-clerodane derivatives (3-7,9-11) have been obtained. The naturally occurring diterpenoid teuscordinon (12) has also been synthesized from teubotrin (1), showing thereby how some of these transformations can be useful for the synthesis of other natural neo-clerodane diterpenes. The latter are of interest due to their activity as insect antifeedants and other important biological properties. 相似文献
959.
Ballesteros I. Ballesteros M. CabaÑas A. Carrasco J. MartÍn C. Negro M. J. Saez F. Saez R. 《Applied biochemistry and biotechnology》1991,(1):307-315
A total of 27 yeast strains belonging to the groupsCandida, Saccharomyces, andKluyveromyces were screened for their ability to grow and ferment glucose at temperatures ranging 32-45°C.
K. marxianus andK. fragilis were found to be the best ethanol producing organisms at the higher temperature tested and, so, were selected for subsequent
simultaneous saccharification and fermentation (SSF) studies. 相似文献
960.
Bitter Istvn Hermecz Istvn Tth Gbor Dvortsk Pter Bende Zoltn Mszros Zoltn 《Tetrahedron letters》1979,20(52):5039-5040
The 9-carbamoyl derivatives /–/ can be prepared from title compound // with isocyanates //. – are mixtures of the cis /Z/ and trans /E/ imines and the enamine /e/. The equilibrium depends on the substituents R,X and on the solvent. 相似文献