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101.
Miroslav Stredanský Lubomir Kremnický Ernest Sturdik Anna Fecková 《Applied biochemistry and biotechnology》1993,38(3):269-276
Production of α-amylase withB. subtilis CCM 2722 in an aqueous two-phase polyethylene glycol/dextran system integrated with product purification by affinity chromatography on crosslinked starch during cultivation was studied. The medium was drawn from the bioreactor to the external settler during fermentation. After phase separation in the settler the dextran-rich bottom phase with cells was returned to the bioreactor. The PEG-rich top phase was pumped to the column with crosslinked starch and returned to the bioreactor after α-amylase adsorption. The same volumetric productivities, 0.53 U/mL/h, were reached in both batch and described process, but total productivity of the latter method was much higher owing to shortening upstream and downstream processing time. The enzyme of 98% homogenity in 95% yield was obtained after its elution from the column. 相似文献
102.
103.
Shin Y Fournier JH Brückner A Madiraju C Balachandran R Raccor BS Edler MC Hamel E Sikorski RP Vogt A Day BW Curran DP 《Tetrahedron》2007,63(35):8537-8562
Total syntheses of (−)-dictyostatin, 6,16-bis-epi-dictyostatin, 6,14,19-tris-epi-dictyostatin, and a number of other isomers and analogs are reported. Three main fragments—top, middle, and bottom—were first assembled and then joined by olefination or anionic addition reactions. After appending the two dienes at either end of the molecule, macrolactonization and deprotection completed the syntheses. The work proves both the relative and absolute configurations of (−)-dictyostatin. The compounds were evaluated by cell-based measurements of increased microtubule mass and antiproliferative activity, and in vitro tubulin polymerization assays as well as competitive assays with paclitaxel for its binding site on microtubules. These assays showed dictyostatin to be the most potent of the agents and further showed that the structural alterations caused from 20- to >1000-fold decreases in activity. 相似文献
104.
The problem of identification in fuzzy systems described by the use of fuzzy equation is considered. The identification method and its performance index is also presented. The formal procedure of the identification algorithm is illustrated by means of a numerical example. The possibility of using the proposed algorithm for the solution of a control problem is given as well. 相似文献
105.
106.
The overall photobromination reactions have been studied using a competitive technique. Relative Arrhenius parameters were obtained for the rate-determining step These were placed on an absolute basis using previous-absolute values of A and E for RFI=CF3I. The activation energies were used to calculate bond dissociation energies D(R? I) with the following results:
RF? | E16 | D(RF?I)(kcal/mole) |
---|---|---|
CF3I a a E16 from [1] | 10.8 | 52.6 |
C2F5I | 8.8 | 50.6 |
n-C3F7I | 7.4 | 49.2 |
i-C3F7I | 7.5 | 49.2 |
n-C4F9I | 6.7 | 48.4 |
- a E16 from [1]
107.
This paper deals with some problems of the control of fuzzy systems described by means of a relational equation of the type: Xκ + 1 = Uκ ° Xκ ° R. The basic aspects such as mutual identification and control, stabilization control, control with constraints, generation of control rules of a fuzzy logic controller, important from the theoretical and applicational point of view are discussed and illustrated by means of numerical examples. 相似文献
108.
J. Ernest Wilkins Jr. 《Applied Mathematics and Optimization》1975,2(3):265-270
Let? be a Hilbert space over the field of complex numbers, with inner product (g,h). Letf be a fixed element in?, and letH be a compact, self-adjoint linear operator on?. We find the maximum value ofQ f (u)=|(f,u)|2 in the classU of elementsu in? for which (u,u)=1, (u, Hu)=0. 相似文献
109.
Charles W. Jefford Grald Bernardinelli Ernest C. McGoran 《Helvetica chimica acta》1984,67(7):1952-1956
The reaction of 4-hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with acetaldehyde using trimethylsilyl trifluoromethanesulfonate as catalyst gives 1,1′-bis[(1,3,5-trimethyl-4-oxo-2,5-cyclohexadienyl) peroxy]diethyl ether ( 7 ) in 70% yield. The structure of this unusual acetal was determined by X-ray analysis. 相似文献
110.
Epithennal neutron activation analysis has been applied to the determination of arsenic and gallium in standard materials at trace concentrations. The reduction of 24Na activity compared to thermal neutron activation is advantageous. Arsenic detection limits (1σ) are 0.04 and 0.015 μg for inorganic and organic materials, respectively. The corresponding gallium detection limits, for the best cases, are 0.13 and 0.29 μg. Gallium determinations with the 834-keV photopeak of 72Ga suffered interferences attributed to the threshold reaction 54Fe(n,p) 54Mn; the less intense 72Ga peaks at 629 and 2200 keV provided quantitative results for all samples tested. Gallium detection limits with the less intense, but more reliable 629-keV peak were 0.9 and 0.1 μg for inorganic and organic materials, respectively. Arsenic determinations are best performed with the more intense 76As 559-keV line, as the 657-keV line has an unknown interference. 相似文献