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961.
对工业产品生产许可证管理方面存在的一些问题进行了探讨。经分析认为,在做好实地核查及证后监管的前提下,生产许可证制度的关键在于宣贯和相关细节的明确上。  相似文献   
962.
In the thermochemical water-splitting iodine–sulfur process for hydrogen production, new polymer electrolyte membranes were applied in an electro-membrane process (electro-electrodialysis, EED) to increase the HI molality of HIx solution (HI + I2 + H2O mixture) to be over quasi-azeotropic. Radiation grafting of a styrene monomer into a poly(ethylene-co-tetrafluoroethylene) base film and subsequent sulfonation provided electrolyte membranes that had ion exchange capacities (IECs) of 1.1–1.6 mmol/g. With the EED of the HIx solutions using [HI] = [I2] = 10 mol/kg at 40 °C the transport number of protons, ratio of permeated quantities of water to the protons, and current efficiency all appeared to depend on the IEC of the resulting membranes. When compared to Nafion, the self-made membranes exhibited lower electric cell resistance, and thereby decreasing up to 32% of the overall energy required in the concentration operation.  相似文献   
963.
Ce掺杂K_2La_2Ti_3O_(10)催化剂的可见光高效催化制氢的研究   总被引:1,自引:0,他引:1  
采用高温固相法合成了铈掺杂的K2La2Ti3O10催化剂,利用X射线衍射(XRD)、紫外-可见漫反射(UV-visDRS)、透射电镜(TEM)和X射线光电子能谱(XPS)对催化剂进行了表征.考察了催化剂的可见光催化分解甲醇水溶液制氢的活性,并对可见光催化机理进行了分析.研究表明,铈的掺杂没有改变K2La2Ti3O10的微晶结构,并使催化剂粒径有所减小.紫外可见漫反射分析表明禁带宽度为2.3eV左右,对可见光具有较高吸收.XPS表明La和Ti为+3和+4价,而Ce则是+3和+4的混合价态.担载2wt%Pt后,在可见光下光催化活性大大提高,当铈的掺杂量为0.5mol%(即Ce取代La的摩尔百分量)时,光催化活性达到最大,产氢速率为0.05mmol/h;光照5h后产氢量为0.22mmol,而纯K2La2Ti3O10的产氢量只有0.037mmol.  相似文献   
964.
An overview of spectroscopic diagnostics techniques for low temperature plasmas is presented with an emphasis to electron number density — Ne measurement. Stark broadening of non-hydrogenic atom and positive ion spectral lines is given. The attention is drawn to experimental techniques used for line intensity and line profile measurement. Self-absorption test, importance of Abel inversion, deconvolution of experimental line profiles and measurement of line asymmetry are treated in some detail in order to improve Ne measurements. Finally the sources of theoretical and experimental Stark broadening data are reviewed and some details discussed.  相似文献   
965.
A variable B0 field static (broadline) NMR study of a large suite of niobate materials has enabled the elucidation of high‐precision measurement of 93Nb NMR interaction parameters such as the isotropic chemical shift (δiso), quadrupole coupling constant and asymmetry parameter (CQ and ηQ), chemical shift span/anisotropy and skew/asymmetry (Ωδ and κ/ηδ) and Euler angles (α, β, γ) describing the relative orientation of the quadrupolar and chemical shift tensorial frames. These measurements have been augmented with ab initio DFT calculations by using WIEN2k and NMR‐CASTEP codes, which corroborate these reported values. Unlike previous assertions made about the inability to detect CSA (chemical shift anisotropy) contributions from NbV in most oxo environments, this study emphasises that a thorough variable B0 approach coupled with the VOCS (variable offset cumulative spectroscopy) technique for the acquisition of undistorted broad (?1/2?+1/2) central transition resonances facilitates the unambiguous observation of both quadrupolar and CSA contributions within these 93Nb broadline data. These measurements reveal that the 93Nb electric field gradient tensor is a particularly sensitive measure of the immediate and extended environments of the NbV positions, with CQ values in the 0 to >80 MHz range being measured; similarly, the δiso (covering an approximately 250 ppm range) and Ω values (covering a 0 to approximately 800 ppm range) characteristic of these niobate systems are also sensitive to structural disposition. However, their systematic rationalisation in terms of the Nb? O bond angles and distances defining the immediate NbV oxo environment is complicated by longer‐range influences that usually involve other heavy elements comprising the structure. It has also been established in this study that the best computational method(s) of analysis for the 93Nb NMR interaction parameters generated here are the all‐electron WIEN2k and the gauge included projector augmented wave (GIPAW) NMR‐CASTEP DFT approaches, which account for the short‐ and long‐range symmetries, periodicities and interaction‐potential characteristics for all elements (and particularly the heavy elements) in comparison with Gaussian 03 methods, which focus on terminated portions of the total structure.  相似文献   
966.
In this article, we extend a previous work toward presenting a theoretical study of the effects of Fermi resonances and the fundamental anharmonic coupling parameter α between the high‐frequency mode and the H‐bond bridge. The model incorporates (i) both intrinsic anharmonicities of the fast mode (double well potential) and the H‐bond Bridge (Morse potential), (ii) strong anharmonic coupling theory, (iii) Fermi resonances by the aid of an anharmonic coupling between the fast mode and one or several harmonic bending modes, (iv) quadratic modulation of both the angular frequency and the equilibrium position of the X? …Y stretching mode on the intermonomer ? H… motions, and (v) the quantum direct (fast and bending modes) and indirect dampings (slow mode). The IR spectral density is obtained by Fourier transform of the autocorrelation function of the transition dipole moment operator of the X? H bond. The numerical calculation shows that Fermi resonances generate very complicated profiles with multisubstructure and also provide a direct evidence of Fermi resonances which were predicted to be a major feature of H‐bonds. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010  相似文献   
967.
An effective method for producing methyl 4-bromo-3-hydroxybutyrate enantiomers was developed using an engineered protein. Escherichia coli transformant cells containing a mutant β-keto ester reductase (KER-L54Q) from Penicillium citrinum and a cofactor-regeneration enzyme such as glucose dehydrogenase (GDH) or Leifsonia sp. alcohol dehydrogenase (LSADH) were used to produce methyl (S)-4-bromo-3-hydroxybutyrate from methyl 4-bromo-3-oxobutyrate. On the other hand, the production of methyl (R)-4-bromo-3-hydroxybutyrate was achieved by asymmetric reduction of methyl 4-bromo-3-oxobutyrate with a mutant phenylacetaldehyde reductase (PAR-HAR1) from Rhodococcus sp. ST-10.  相似文献   
968.
The environment of Eu3+ in zinc-thallium-tellurite glass of the molar composition 60TeO2-30TlO0.5-9.9ZnO-0.1Eu2O3 was investigated by laser-induced fluorescence line narrowing (FLN) techniques using Eu3+ as a local site probe. From the site selective luminescence spectra of Eu3+ at 7 K, the energies of the Stark components of the 7F1 and 7F2 states were recorded and then the crystal field parameters Bnm were calculated assuming a C2v site symmetry. The ratios B22/B20 and B44/B40 for each excitation energy within 7F0-5D0 transition were obtained and compared with the values calculated for Eu3+ in other types of glasses.  相似文献   
969.
A method in which antibodies are produced by using an immunogen heterogeneously conjugated with two or more kinds of haptens having unlike chemical structures against a same carrier protein was offered as an efficient approach for development of antibody to low molecular compounds. To appreciate the potentiality of the approach, 17β-estradiol (E2) and testosterone were selected as model compounds. The I50 values of antiserum developed were 6 and 8 μg L−1 with the detection limits of 0.02 and 0.15 μg L−1 for E2 and testosterone, respectively. Antiserum owned an interesting characteristic that it was possible to independently analyze E2 and testosterone without mutual interference by making proper use of coating antigens. When using β-estradiol 17-hemisuccuinate (EH) conjugated with bovine serum albumin (BSA) as a coating antigen, the enzyme-linked immunosorbent assay (ELISA) was very selective to E2 and some estrogen analogues. Therefore, if testosterone coexisted in the ELISA for E2 detection, it showed no interference with it. From these findings, it was suggested that the verified method was an efficient and rational approach in development of polyclonal antibody to low molecular compounds.  相似文献   
970.
A rapid micro‐analytical multiresidue method was developed for analysis of pyrethroids (kadethrin K, cypermethrin C and permethrin P) in soil micro‐sample (200 mg). It uses on‐line flow‐through extraction of soil micro‐samples (packed into a short glass column) with a methanol‐aqueous citric acid buffer mixture, successive on‐line SPE preconcentration of analytes from the extract and on‐line RP‐HPLC analysis with UV photometric detection. The separation of pyrethroids is performed on a Purospher RP‐18e column with methanol/water as mobile phase. Effects of sorbent placed at the bottom of a short column holding the soil sample and different kinds of on‐line SPE columns were tested. Besides, the influence of volume of the effluent on the pyrethroids recovery was also studied. Calibration curves were linear over the range assayed from 0.01 to 0.2 μg/mL with correlation coefficients of linear regression (least‐squares method) in the range 0.998–0.999. Recovery studies were carried out at 0.25–1.00 μg/g dry soil fortification level and obtained recoveries were for K 81–84%, C 56–59% and for P 58–63%. Achieved LOD (confidence band) of studied pyrethroids were for large‐volume injection (1 mL) 4.5 ng K, 3.7 ng C, 3.6 ng P or 27 ng/g K, 32 ng/g C and 29 ng/g P in dry soil “solid sampling HPLC”.  相似文献   
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