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排序方式: 共有107条查询结果,搜索用时 31 毫秒
41.
K. L. Ramakumar V. A. Raman V. L. Sant V. D. Kavimandan H. C. Jain 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(2):467-471
Determination of trace impurities in zircaloy-2 and tellurium by Spark Source Mass Spectrometry (SSMS) is reported. The advantage of SSMS lies in the fact that along with metallic trace constituents even the nonmetallic impurities and gases including hydrogen can also be determined. 相似文献
42.
Treatment of 2-trifluoroacetamido-4-(trifluoromethyl)thiazole with two equivalents of n-butyllithium at -78° produced the thiazole dianion 5 in situ, which reacted preferentially at the 5-position with a variety of electrophiles. These electrophiles include: an aldehyde, ketone, chloroformate, acid chloride, phosphorus oxychloride, silicon chloride, and disulfide. Dianion 5 also combined with dibromodifluoromethane at -98° to give the corresponding 5-(bromodifluoromethyl)thiazole 7 , which is an unusual reaction for an aromatic or heteroaromatic system. Compound 7 was converted to a 4,5-bis-(trifluoromethyl)thiazole 8 using tetrabutylammonium fluoride. 相似文献
43.
De Carvalho M. E. A. Monteiro M. C. Bon E. P. S. Sant’Anna G. L. 《Applied biochemistry and biotechnology》1998,(1):955-966
The production of lignin peroxidase fromPhanerochaete chrysosporium was studied using immobilized mycelia in nylon-web cubes in semicontinuous fermentation using glucose pulses or ammonium
tartrate pulses. Consistent enzyme production was achieved when glucose pulses were used, leading to an average activity of
253 U/L. The crude enzyme was added to eucalyptus kraft pulp before conventional and ECF bleaching sequences. Optimization
of the enzymatic pretreatment led to the following operational conditions: enzyme load of 2 U/g of pulp, hydrogen peroxide
addition rate of 10 ppm/h, and reaction time of 60 min. Pulp final characteristics were dependent on the chemical treatment
sequence that followed enzymatic pretreatment. The chief advantage of enzymatic pretreatment was pulp viscosity preservation,
which was observed in most of the experiments carried out with seven different chemical treatment sequences 相似文献
44.
B. R. Sant 《Fresenius' Journal of Analytical Chemistry》1955,148(3):176-178
Summary A volumetric method for the estimation of lead and barium, based on precipitation of the respective metal chromate and subsequent iodometric titration of the chromic acid against standard As2O3 solution in a suitably adjustedph range, is described. Estimation of Ag, Sr and Tl on similar lines is suggested.The author is grateful to Professor S. S. Joshi for research facilities and interest in the work. 相似文献
45.
Pereira-Meirelles Fatima Ventura Rocha-LeãO Maria Helena Miguez Anna Geraldo Lippel Santť 《Applied biochemistry and biotechnology》1997,(1):73-85
Although Upases have been intensively studied, some aspects of enzyme production like substrate uptake, catabolite repression,
and enzyme stability under long storage periods are seldom discussed in the literature. This work deals with the production
of lipase by a new selected strain ofCandida lipolytica. Concerning nutrition, it was observed that inorganic nitrogen sources were not as effective as peptone, and that oleic acid
or triacylglycerides (TAG) were essential carbon sources. Repression by glucose and stimulation by oleic acid and long chain
TAG (triolein and olive oil) were observed. Extracellular lipase activity was only observed at high levels at late stationary
phase, whereas intracellular lipase levels were constant and almost undetectable during the cultivation period, suggesting
that the produced enzyme was attached to the cell wall, mainly at the beginning of cultivation. The crude lipase produced
by this yeast strain shows the following optima conditions: pH 8.0–10.0, temperature of 55°C. Moreover, this preparation maintains
its full activity for at least 370 d at 5°C. 相似文献
46.
Ke Ruan Shengtian Yang Karey A. Van Sant John J. Likos 《Magnetic resonance in chemistry : MRC》2009,47(8):693-700
Combined verification using 1‐D proton and HSQC has been proved to be quite successful; the acquisition time of HSQC spectra, however, can be limiting in its high‐throughput applications. The replacement with Hadamard HSQC can significantly enhance the throughput. We hereby propose a protocol to optimize the grouping of the predicted carbon chemical shifts from the proposed structure and the associated Hadamard frequencies and bandwidths. The resulting Hadamard HSQC spectra compare favorably with their Fourier‐transformed counterparts, and have demonstrated to perform equivalently in terms of combined verification, but with several fold enhancement in throughput, as illustrated for 21 commercial available molecules and 16 prototypical drug compounds. Further improvement of the verification accuracy can be achieved by the cross validation from Hadamard TOCSY, which can be acquired without much sacrifice in throughput. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
47.
Mrinal K. Mandal Sudhindra B. Sant Prashant K. Bhattacharya 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,373(1-3):11-21
Pervaporative performances were investigated for dehydration of water–acetonitrile using nanocomposite metal oxide and Pervap® 2202 membranes. Poly (vinyl alcohol) based nanocomposite metal oxide membranes were prepared through co-precipitation of different amounts of Fe (II) and Fe (III). The freestanding nanocomposite metal oxide membranes were characterized by Transmission electron microscopy and X-ray diffraction. Sorption studies evaluated the extent of interaction and degree of swelling of the membranes. Fe containing PVA polymer matrix showed improved flux and selectivity. In order to observe simultaneous effect of flux and selectivity, pervaporation separation index showed 10 wt.% iron oxide containing membrane is the most amongst all tested. The diffusion coefficients were calculated using pervaporation results and sorption kinetics data. An attempt was made to predict sorption selectivity thermodynamically. PV separation factor was observed to be governed by sorption and/or diffusion phenomena and sorption selectivity was found to be higher than PV separation factor. Prediction of concentration profile in the membrane was also attempted and the results showed that water concentration in the membrane drops down with increase in membrane thickness. 相似文献
48.
C. B. Zamboni M. F. Suzuki S. Metairon M. D. F. Carvalho O. A. Sant’Anna 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(1):97-99
The Br (0.0022 ± 0.0006 gL−1), Ca (0.113 ± 0.012 gL−1), Cl (3.07 ± 0.36 gL−1), K (2.63 ± 0.14 gL−1), Mg (0.045 ± 0.002 gL−1) and Na (2.09 ± 0.10 gL−1) concentrations were determined in whole blood of SJL/J mice using the Neutron Activation Analysis (NAA) technique. Eleven
whole blood samples were analyzed in the IEA-R1 nuclear reactor at IPEN (S?o Paulo, Brazil). These data contribute for applications
in veterinary medicine related to biochemistry analyses using whole blood. Moreover, the correlation with human blood estimation
allows to checking the similarities for studying muscular dystrophy using this model animal. 相似文献
49.
Janaína Marques Rodrigues Carlos Mauricio R. Sant’Anna Victor Marcos Rumjanek João Batista Neves DaCosta 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):40-56
A series of 22 dialkylphosphorylydrazones (dialkyl ester, N′-[(1E)-(R1 phenyl)methylene]-phosphorohydrazidic acid), 20 of them new, along with three new N,N′-bis (diisobutylphosphorylthioamide)diamines (bis-[diisobutyl ester), N-thioxomethylene]-, diamine)phosphora-midic acid, were prepared and characterized by IR, 1H NMR, 13C NMR, 31P NMR, and mass spectrometry. The analysis of 1H NMR, 13C NMR, 31P NMR, and NOE spectra confirmed the observation of the single diastereoisomer E in the synthesis of dialkylphosphorylydrazones. The results of a molecular modeling study performed in order to investigate the mechanism of the synthesis of dialkylphosphorylydrazones are in agreement with the experimental results, i.e., the favored formation of diastereoisomer E over Z. 相似文献
50.