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41.
42.
A novel two-dimensional electrophoretic system for the control of electroosmosis in capillary zone electrophoresis has been developed and evaluated for rapid separations of proteins. The system comprises uncoated and polyether-coated fused silica capillaries coupled in series. An equation relating the average electroosmotic flow velocity in the coupled capillaries to the intrinsic electroosmotic velocities of the connected segments and their corresponding lengths has been derived and verified experimentally. This approach has the advantage of enabling the electroosmotic flow to be tuned independently of the applied voltage. As a consequence, rapid protein analysis at relatively low field strength was achieved without sacrificing the high separation efficiencies obtained with surface-modified capillaries. 相似文献
43.
Ziad Omran 《Tetrahedron letters》2009,50(20):2434-130
We report herein the synthesis and the development of homo-bifunctional photo-cleavable sulfhydryl group cross-linkers that are able to react and then to photorelease two cysteines leading to the photoregulation of cross-linkers cleavage. 相似文献
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45.
Yoshinori Fujimoto Miki Kimura Akihiro Takasu Fathy A.M. Khalifa Masuo Morisaki Nobuo Ikekawa 《Tetrahedron letters》1984,25(14):1501-1504
Deuterated stigmasterols (10, 11 and 12) were chemically synthesized and fed to silk-worm larvae. GC-MS analysis of the metabolites, cholesterol (4) and desmosterol (6), indicates the migration of 25-hydrogen to C-24 position during stigmasterol dealkylation. 22,24(28)-Dienes(8a and 8b) were shown to be converted to 22,24-diene (5), desmosterol and cholesterol. 相似文献
46.
Amino acid and peptide esters protected by the PChd group can be deprotected cathodically under mild conditions. 相似文献
47.
A. A. Helal D. M. Imam S. M. Khalifa H. F. Aly 《Journal of Radioanalytical and Nuclear Chemistry》1998,232(1-2):159-161
The effect of some environmental ligands and certain fertilizers on the complexation of strontium with humic acid wasinvestigated
colorimetrically and radiometrically. The results indicate that Na2-EDTA, Na3-citrate and NaCl compete to complex strontium in solution with the sequence: chloride < citrate < EDTA while Na3-phosphate has the reverse behavior. In the case of nitrogen containing fertilizers, the results show that urea, Mg-ammonium
nitrate and ammonium nitrate increase the availability of strontium to plants and microorganisms. 相似文献
48.
Summary The reaction between molybdenum and the sulphonic acid azo dye Solochrome Violet R.S. has proved to be a suitable one for the microdetermination of Mo amounts covering the range of 0.3 to 10 ppm in purely aqueous solutions. The variation of extinction with concentration conforms satisfactorily with Beer's law throughout the whole range. Very many cations and anions do not interfere with such a determination. Ferric iron up to 2 mg per 25 ml is completely masked with ascorbic acid.Part II: Khalifa, H., and S. W. Bishara: Z. analyt. Chem. 178, 345 (1960). 相似文献
49.
H. Khalifa 《Fresenius' Journal of Analytical Chemistry》1958,161(6):401-406
Summary Mercuric nitrate has proved to be a suitable back titrant for EDTA amounts in excess of those reacting quantitatively with thorium amounts ranging from 46 g up to 25 mg. End points are detected potentiometrically with reasonable jumps amounting to an average of 70 mV per 0.1 ml titrant. Thorium can be determined with fair accuracy, in the presence of double its amount of uranium. 相似文献
50.