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Cycloaddition reactions between 2-vinylthiophen and the dienophiles maleic anhydride, dimethyl acetylenedicarboxylate,' methyl propiolate, and methyl acrylate, are reported. Products include simple benzo[b]thiophen carboxylates (6, 13, 17) and reduced derivatives (3, 4, 18). The acetylenic dienophiles also gave a dihydrobenzthienyl-acrylate (16) or -fumarate (11), and the dithienylcyclohexene esters (7) and (14). 相似文献
3.
Determination of linuron in soil by stripping voltammetry with a carbon fiber microelectrode 总被引:1,自引:0,他引:1
A carbon fiber microelectrode was used for the electroanalytical determination of Linuron (LIN) in soil extracts. The microelectrode was subjected to an electrochemical pretreatment in order to improve the herbicide adsorption on the electrode surface. With this preconcentration step, detection limits of 80 ng ml−1 and determination limits of 260 ng ml−1 were reached. Optimal conditions with respect to accumulation time and potential, scan rate and pH were established. The LIN was determined in a soil sample with the method proposed and the results found were comparable to those obtained by HPLC. 相似文献
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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
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José M. Sánchez-Montero JOSé V. Slnisterra Antonio Ballesteros 《Applied biochemistry and biotechnology》1989,22(2):205-214
The endonuclease from S. aureus has been immobilized on ground maize cob, previously activated with tosyl chloride. Pretreatment of the support on acid before tosylation yielded the best insoluble enzyme derivatives. The catalytic activity has been evaluated as percent of total hydrolysis attained in a batch reactor using DNA as a model substrate. The derivatives prepared are very resistant to high temperatures under conditions of catalysis (24 h at 45 degrees C). For these long reaction times, the extent of hydrolysis in the presence of small amounts of organic solvent (dimethyl sulfoxide at 2 percent) is larger than in plain buffer (Tris). This type of derivative could be very useful for the removal of nucleic acids from single-cell protein concentrates. 相似文献
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Juan J. Nuño Ballesteros 《Geometriae Dedicata》1993,47(3):241-254
We study the singularities of the tangent developable of a generic curve in 3 and prove that if the curve has no torsion zero points, the number of triple points of that surface must be even. 相似文献
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