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排序方式: 共有215条查询结果,搜索用时 31 毫秒
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2.
Sibel Akgün Gülsüm Ekici Nilüfer Mutlu Necati Beşirli Baki Hazer 《Journal of Polymer Research》2007,14(3):215-221
Modification of chitosan by grafting of vinyl butyrate was carried out in homogeneous phase using potassium persulfate as
redox initator and 1.5% acetic acid as solvent. The percent grafting and grafting efficiency were analysed and the high grafting
efficiency up to 94% was observed. The effects of reaction variables such as monomer concentration, initiator concentration,
temperature and reaction time were investigated. It was observed that the solubility of chitosan was markedly reduced after
grafting with vinyl butyrate. The grafted product is insoluble in common organic solvents as well in dilute organic and inorganic
acids. Characterization of the graft copolymers were carried out by using Fourier Transform Infrared Spectroscopy (FTIR),
Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) technics. Characteristic signal of carbonyl
group was observed at 1,731 cm−1 which belongs to the poly vinyl butyrate segments in the graft copolymer. The melting transition of the chitosan main chain
in the copolymer shifted to 124°C from its original value 101°C. In addition to these, we have also studied topology of the
graft copolymer and the SEM micrograph showed continuous homogenous matrix which means there is no phase separation. 相似文献
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Martina Bečvářová 《NTM》2004,12(1):40-48
The paper describes the Czech project in the history of mathematics which was initiated at the Faculty of Mathematics and
Physics of Charles University in Prague at the end of the eighties of the 20th century. Its main aim is to map the development
of mathematical research in the Czech lands in the second half of the nineteenth and the first half of the twentieth century.
The main result of this project is the production of monographs. These chart out the life and work of some prominent Czech
personalities-mathematicians who have had substantial influence on the development of Czech mathematics. The aim of the project,
the structure of the monographs and the general method are discussed in the paper. 相似文献
5.
Phenylalanine Ammonia‐Lyase‐Catalyzed Deamination of an Acyclic Amino Acid: Enzyme Mechanistic Studies Aided by a Novel Microreactor Filled with Magnetic Nanoparticles 下载免费PDF全文
Diána Weiser Dr. László Csaba Bencze Gergely Bánóczi Ferenc Ender Dr. Róbert Kiss Eszter Kókai Dr. András Szilágyi Prof. Dr. Beáta G. Vértessy Dr. Ödön Farkas Dr. Csaba Paizs Prof. Dr. László Poppe 《Chembiochem : a European journal of chemical biology》2015,16(16):2283-2288
Phenylalanine ammonia‐lyase (PAL), found in many organisms, catalyzes the deamination of l ‐phenylalanine (Phe) to (E)‐cinnamate by the aid of its MIO prosthetic group. By using PAL immobilized on magnetic nanoparticles and fixed in a microfluidic reactor with an in‐line UV detector, we demonstrated that PAL can catalyze ammonia elimination from the acyclic propargylglycine (PG) to yield (E)‐pent‐2‐ene‐4‐ynoate. This highlights new opportunities to extend MIO enzymes towards acyclic substrates. As PG is acyclic, its deamination cannot involve a Friedel–Crafts‐type attack at an aromatic ring. The reversibility of the PAL reaction, demonstrated by the ammonia addition to (E)‐pent‐2‐ene‐4‐ynoate yielding enantiopure l ‐PG, contradicts the proposed highly exothermic single‐step mechanism. Computations with the QM/MM models of the N‐MIO intermediates from l ‐PG and l ‐Phe in PAL show similar arrangements within the active site, thus supporting a mechanism via the N‐MIO intermediate. 相似文献
6.
Lokman Uzun Ali Kara Bilgen Osman Erkut Yılmaz Necati Beşirli Adil Denizli 《应用聚合物科学杂志》2009,114(4):2246-2253
The aim of this study was to prepare magnetic beads that could be used for the removal of heavy‐metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [m‐poly(EGDMA–VTAZ)] beads were produced by suspension polymerization in the presence of a magnetite Fe3O4 nanopowder. The specific surface area of the m‐poly(EGDMA–VTAZ) beads was 74.8 m2/g with a diameter range of 150–200 μm, and the swelling ratio was 84%. The average Fe3O4 content of the resulting m‐poly(EGDMA–VTAZ) beads was 14.8%. The maximum binding capacities of the m‐poly(EGDMA–VTAZ) beads from aquous solution were 284.3 mg/g for Hg2+, 193.8 mg/g for Pb2+, 151.5 mg/g for Cu2+, 128.1 mg/g for Cd2+, and 99.4 mg/g for Zn2+. The affinity order on a mass basis was Hg2+ > Pb2+ > Cu2+ > Cd2+> Zn2+. The binding capacities from synthetic waste water were 178.1 mg/g for Hg2+, 132.4 mg/g for Pb2+, 83.5 mg/g for Cu2+, 54.1 mg/g for Cd2+, and 32.4 mg/g for Zn2+. The magnetic beads could be regenerated (up to ca. 97%) by a treatment with 0.1M HNO3. These features make m‐poly(EGDMA–VTAZ) beads potential supports for heavy‐metal removal under a magnetic field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
7.
8.
Moisture adsorption isotherms and thermodynamics properties of sucuk (Turkish dry-fermented sausage) 总被引:1,自引:0,他引:1
Bilgehan Polato?luA. Vildan Be?e Mükerrem KayaNesimi Akta? 《Food and Bioproducts Processing》2011,89(4):449-456
Moisture adsorption isotherms of sucuk were determined using the isopiestic method at 10 °C, 20 °C and 30 °C and within the range of 0.2-0.9 water activity. The isotherms of sucuk exhibited Type II behavior according to BET classification. The adsorption data were analyzed using mathematical equations of Halsey, Caurie, Peleg, Smith, Oswin, Henderson, Modified-BET, GAB, Ferro-Fontan and Harkins-Jura. The best fit of experimental data was obtained with Peleg equation in the range of temperatures and water activities investigated. Thermodynamic properties such as differential enthalpy and entropy, enthalpy-entropy compensation, spreading pressure, net integral enthalpy and entropy were determined from moisture adsorption isotherm data of sucuk. The net isosteric heat of sorption and differential entropy decreased with increasing moisture contents in an exponential function. The spreading pressure increased with increasing water activity, and decreased with increasing temperature. The net integral enthalpy decreased with increased moisture content. The integral entropy increased with moisture content, but it was negative in value. The enthalpy-entropy compensation theory was applied to water adsorption of sucuk. 相似文献
9.
I. Bešlić L. Vranješ Markić J. Casulleras J. Boronat 《Journal of Low Temperature Physics》2013,171(3-4):436-442
The ground-state properties of spin-polarized deuterium with only one occupied nuclear spin state (D↓1) at zero temperature are studied by means of the variational Monte Carlo (VMC) method. Influence of the backflow correlations on the ground-state energy of this Fermi system under investigation is also explored. The calculations have been performed using several interatomic potentials and the quantum phase of the D↓1 system is discussed. Our results are compared with other previously reported variational results. 相似文献
10.
In the paper the main goals and progress of the surveillance specimen programme for the RPVs WWER-440/213 in Jaslovské Bohunice V-2 and Mochovce NPPs are presented. At Jaslovské Bohunice V-2, the standard surveillance specimen programme (SSSP) was finished and so-called ‘Extended Surveillance Specimen Programme’ (ESSP) was prepared on the base of its critical analysis. For first two units of the Mochovce NPP completely new programmes of irradiation embrittlement monitoring called ‘Modern Surveillance Specimen Programme’ is prepared. It is based on the experience with SSSP and ESSP as well as the recommendations of IAEA experts. This programme will serve for Mochovce NPP during all planned service life. The experience of ESSP application on the 3rd and 4th units in Jaslovské Bohunice V-2 NPP are presented in the paper too. 相似文献