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521.
Marek Kara? 《Journal of Pure and Applied Algebra》2008,212(5):1145-1148
Let f:V→W be a finite polynomial mapping of algebraic subsets V,W of and , respectively, with n≤m. It is known that f can be extended to a finite polynomial mapping . Moreover, it is known that, if V,W are smooth of dimension k,4k+2≤n=m, and f is dominated on every component (without vertical components) then there exists a finite polynomial extension such that , where means the number of points in the generic fiber of h. In this note we improve this result. Namely we show that there exists a finite polynomial extension such that . 相似文献
522.
Using the relativistic Hartree-Fock (HFR) method developed by Cowan, we calculated the energy levels, Landé g-factors, and lifetimes for nd (n = 5–25), ns (n = 6–24), ng (n = 5–25), nf (n = 4–22), and np (n = 6–25) excited levels of doubly ionized lanthanum (La III, Z = 57). We compared the results with previously reported calculations
and experiments. 相似文献
523.
Bilgen Osman Ali Kara Emel Demirbel Senay K?k Necati Be?irli 《Applied biochemistry and biotechnology》2012,168(2):279-294
Designing an immobilised metal ion affinity process on large-scale demands that a thorough understanding be developed regarding the adsorption behaviour of proteins on metal-loaded gels and the characteristic adsorption parameters to be evaluated. In view of this requirement, interaction of ??-amylase as a model protein with newly synthesised magnetic-poly(divinylbenzene-1-vinylimidazole) [m-poly(DVB-VIM)] microbeads (average diameter, 53?C212???m) was investigated. The m-poly(DVB-VIM) microbeads were prepared by copolymerising of divinylbenzene (DVB) with 1-vinylimidazole (VIM). The m-poly(DVB-VIM) microbeads were characterised by N2 adsorption/desorption isotherms, electron spin resonance, elemental analysis, scanning electron microscope and swelling studies. Cu2+ ions were chelated on the m-poly(DVB?CVIM) beads and used in adsorption of ??-amylase in a batch system. The maximum ??-amylase adsorption capacity of the m-poly(DVB?CVIM)?CCu2+ beads was determined as 10.84?mg/g at pH?6.0, 25?°C. The adsorption data were analyzed using three isotherm models, which are the Langmuir, Freundlich and Dubinin?CRadushkevich isotherm models. The pseudo-first-order, pseudo-second-order, modified Ritchie??s-second-order and intraparticle diffusion models were used to test dynamic experimental data. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. 相似文献
524.
Yasemin Kara Baris Avar Ahmet Kayraldiz Bilgehan Guzel Mukerrem Kurtoglu 《Heteroatom Chemistry》2011,22(2):119-130
A new ONNO‐type azomethine ligand, 2,2′‐(ethane‐1,2‐diylidenedinitrilo)dibenzoic acid, (YLH2) ( 1 ) has been prepared by the condensation of 2‐aminobenzoic acid and glyoxal. The coordination compounds [Ni(YL)] ( 2 ), [Co(YL)] ( 3 ), [Cu(YL)(H2O)] ( 4 ), [Zn(YL)] ( 5 ), and [Cd(YL)] ( 6 ) of the YLH2 ligand with five transition metal ions, Ni(II) Co(II), Cu(II), Zn(II), and Cd(II) have been prepared. The structures of these new azomethine compounds are proposed on the basis of the elemental analyses, proton nuclear magnetic resonance, infrared, ultraviolet–visible spectroscopy, and X‐ray powder diffraction patterns. Elemental analyses indicate a ligand metal ratio of 1:1 in the coordination compounds. X‐ray powder diffraction parameters for [Cu(YL)(H2O)] and [Cd(YL)] compounds correspond to orthorhombic and monoclinic structures, respectively. The ligand acts as a tetradentate ligand bending through oxygen atoms of the hydroxyl groups of benzoic acid and nitrogen atoms of the azomethine groups. In addition, the ligand and its metal complexes have been studied for their possible genotoxic potential. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:119–130, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20665 相似文献
525.
A new method using multiwalled carbon nanotubes as an SPE adsorbent was developed for the sensitive determination of trace iron and lead prior to flame atomic absorption spectrometry analysis. Iron and lead as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline chelates were adsorbed quantitatively on multiwalled carbon nanotubes at a pH of 6.0 and easily eluted with 10 mL 1 M HNO3. The influences of matrix ions were also examined. The LOD values for iron and lead were calculated as 1.3 and 2.9 microg/L, respectively. Validation of the presented procedure was performed by the analysis of TMDA 54.4 fortified lake water and HR-1 Humber River sediment certified reference materials. The method was successfully applied to the determination of trace iron and lead in real environmental samples, and excellent results were achieved. 相似文献
526.
It is shown that cytochrome c heme lyase (CCHL) attaches heme covalently to peptides composed of the N-terminal segment of cyt c fused to a non-heme containing protein, lending insight into the substrate specificity of CCHL and providing a new route to artificial heme proteins. 相似文献
527.
Türkmen YE Montavon TJ Kozmin SA Rawal VH 《Journal of the American Chemical Society》2012,134(22):9062-9065
A highly effective silver-catalyzed formal inverse electron-demand Diels-Alder reaction of 1,2-diazines and siloxy alkynes has been developed. The reactions provide ready access to a wide range of siloxy naphthalenes and anthracenes, which are formed in good to high yields, under mild reaction conditions, using low catalyst loadings. 相似文献
528.
Nik Norulaini Nik Abd. Rahman Salman Zhari Md. Zaidul Islam Sarker Sahena Ferdosh Mohd Azizi Che Yunus Mohd Omar Abd Kadir 《中国化学会会志》2012,59(4):507-514
A rapid identification, classification and discrimination tool, using Fourier Transform Infrared (FTIR) spectroscopy combined with Principal Component Analysis (PCA), was developed and applied to determine the profile of the Supercritical Fluid Extraction (SFE) of Parkia speciosa seeds under various temperature and pressure conditions (313, 323, 333, 343, 353 and 363 K and 20.68, 27.58, 34.47, 41.37, 48.26, and 55.16 MPa). The separation and identification of the compounds was carried out by Gas Chromatography coupled with Time of Flight Mass Spectrometry (GC/TOF‐MS). This technique has made it possible to detect the variability obtained under different SFE conditions and the separation of different chemical compounds in P. speciosa seeds. The FTIR‐PCA results were verified by GC/TOF‐MS, and the FTIR‐PCA method successfully identified the unsaturated carboxylic acids with the highest percentage area under the different conditions. 相似文献
529.
Meryem Fistikci Ozlem Gundogdu Derya Aktas Hasan Secen M. Fethi Sahin Ramazan Altundas Yunus Kara 《Tetrahedron》2012,68(12):2607-2610
A new synthetic strategy for (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid, a building block in the preparation of sitagliptin and its derivatives, was developed. Pd(OAc)2 catalyzed coupling of 2,4,5-trifluoro-1-iodobenzene with allyl alcohol gave 3-(2,4,5-trifluorophenyl)propanal in a yield of 95%. l-Proline catalyzed reaction of the 3-phenylpropanal (in only 1.2 molar equiv) with nitrosobenzene followed by reduction with NaBH4 and Pd/C catalyzed hydrogenation gave (R)-3-(2,4,5-trifluorophenyl)propane-1,2-diol with >99% ee and 65% yield. Selective tosylation of primary hydroxyl group of the 1,2-propandiol unit followed by cyanide displacement afforded (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanenitrile (80%). The nitrile was converted to the title β-hydroxy acid under basic hydrolysis in a yield of 90%. Thus, (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid was prepared enantioselectively from the starting material in four steps and 45% overall yield. The reaction sequence was repeated with d-proline as the catalyst to give (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid in 45% overall yield and >99% enantiomeric excess. 相似文献
530.