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排序方式: 共有452条查询结果,搜索用时 93 毫秒
71.
The current article is devoted to classify the c-capability of finite dimensional nilpotent Lie algebras with the derived subalgebra of dimension two. 相似文献
72.
Tangestaninejad S Moghadam M Mirkhani V Mohammadpoor-Baltork I Salavati H 《Ultrasonics sonochemistry》2008,15(5):815-822
Na5PV2Mo10O40 supported on nanoporous anatase TiO2 particles, TiO2–PVMo, was used as an efficient photocatalyst for photocatalytic degradation of different dyes by visible light using oxygen as oxidant. This catalyst showed a good catalytic activity in the sonocatalytic and sonophotocatalytic decomposition of different dyes in aqueous solutions. The TiO2–PVMo composite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure TiO2. 相似文献
73.
Sakhaii P Haase B Bermel W 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,191(2):291-303
A new scheme for obtaining HSQC spectra with improved resolution or in a shorter time called SHARC (Shaped Arrayed data aCquisition protocol) is proposed, which uses region selective RF pulses and allows the sweep width to be adjusted individually for each region. It thus bypasses the problems with the Nyquist theorem associated with other method suggested for this purpose. Assignment of the cross-peaks to their respective region is achieved by manipulating the phases of the RF pulses and/or their frequencies. SHARC NMR can be applied without any previous knowledge of the chemical shift distribution, but can be further optimized on the basis of a quick overview spectrum. 相似文献
74.
A simple method is introduced providing a highly clean microextraction for the determination of some anti‐inflammatory drugs as the model analytes in human urine and environmental matrices. This method is based upon the implementation of two consecutive emulsification liquid‐phase microextractions, which are separated by a syringe filtration step. In this method, the organic extraction solvent (dihexyl ether) is dispersed into the aqueous sample solution (20 mL), and the resulting cloudy mixture is passed through a hydrophilic polytetrafluoroethylene syringe filter. By this action, the extraction phase containing the analytes and many interfering species that could be transferred into the organic phase is retained behind the hydrophilic membrane. The filter is then detached from the syringe and attached to another syringe containing an aqueous solution (pH 12.0, 150 μL), and by the in‐syringe dispersion of the organic phase into the aqueous phase, the analytes are selectively back‐extracted into the aqueous phase. The developed method is centrifuge‐free and very simple, and provides a high sample clean‐up in a few minutes. Under the optimized experimental conditions, the developed method provided a linearity in the range of 2.0–2000 ng/mL, a low limit of detection (0.5 ng/mL), and enrichment factors of 47–53. 相似文献
75.
Mohamad Hasan Mohamadzadeh Moghadam Sina Sabury Mohsen Moazzami Gudarzi Farhad Sharif 《Journal of polymer science. Part A, Polymer chemistry》2014,52(11):1545-1554
Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m?1, compared with 20.3 S m?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554 相似文献
76.
Maryam Mohebbi Peyman Salehi Morteza Bararjanian Samad N. Ebrahimi 《Journal of the Iranian Chemical Society》2018,15(1):47-53
In this paper, synthesis of two derivatives of noscapine and their application as organocatalysts in the asymmetric addition of diethylzinc to aromatic aldehydes is reported. The first catalyst (2) was synthesized by the reduction of lactone ring of noscapine to form the corresponding diol, and the second one (3) was prepared by tert-butyl dimethyl silylation of the primary hydroxyl group of 2. Excellent yields and high ees up to 95% were obtained by using 3 as the catalyst. To the best of our knowledge, this is the first report on the application of lactone ring opened noscapinoid compounds as organocatalysts in asymmetric reactions. 相似文献
77.
Iraj Mohammadpoor-Baltork Majid Moghadam Shahram TangestaninejadValiollah Mirkhani Seyedeh Fatemeh Hojati 《Polyhedron》2008
12-Tungstophosphoric acid (TPA) supported on silica, activated carbon and poly(4-styrylmethyl)pyridinium chloride (PMP) were found to be highly efficient catalysts for the synthesis of oxazolines, imidazolines and thiazolines from the condensation of various nitriles with aminoalcohols, ethylenediamine and cisteamine, respectively. In the case of oxazolines, dicyanobenzenes were selectively converted to mono- and bis-oxazolines in the presence of these catalysts. In the reaction of dicyanobenzenes with ethylenediamine, only mono-imidazolines were produced and the remaining cyano group did not react even with long reaction times. In the case of thiazolines, only bis-thiazolines were produced in the reaction of dicyanobenzenes with cysteamine. Furthermore, these catalysts could be recovered and reused without significant loss of their activities. 相似文献
78.
M.M. Yazdanpanah M. Modarres 《The European Physical Journal A - Hadrons and Nuclei》2000,7(4):573-581
In this article we intend to discuss the evolution of polarized and unpolarized structure functions in the (x,Q2) plane. We analyze the proton data on the spin dependence asymmetry A1(x,Q2), by making the dynamical assumption that at low resolution energies, the hadrons consist only of valence quarks and the
scaling violation of F2(x,Q2) at low x comes only from the gluons density. While the sea quark and the gluon distributions are calculated using the inverse
Mellin technique and the various moments of the valence quarks, the valence quark distribution itself is obtained from the
relativistic quark-exchange model. A comparison is made with the corresponding available experimental data. Finally in agreement
with the data, it is demonstrated that there is no significant Q2-dependence of asymmetry A1(x,Q2) for x ranging 0.014 ≤ x ≤ 0.25.
Received: 11 September 1999 / Revised version: 8 December 1999 相似文献
79.
Saeed Montazeri Moghadam Maryam Sadeghi Talarposhti Ali Niaty Farzad Towhidkhah Sajad Jafari 《Nonlinear dynamics》2018,93(3):1183-1199
Recent findings on the dynamical analysis of human locomotion characteristics such as stride length signal have shown that this process is intrinsically a chaotic behavior. The passive walking has been defined as walking down a shallow slope without using any muscular contraction as an active controller. Based on this definition, some knee-less models have been proposed to present the simplest possible models of human gait. To maintain stability, these simple passive models are compelled to show a wide range of different dynamics from order to chaos. Unfortunately, based on simplifications, for many years the cyclic period-one behavior of these models has been considered as the only stable response. This assumption is not in line with the findings about the nature of walking. Thus, this paper proposes a novel model to demonstrate that the knee-less passive dynamic models also have the ability to model the chaotic behavior of human locomotion with some modifications. The presented novel model can show chaotic behavior as a stable and acceptable answer using a chaotic function in heel-strike condition. The represented chaotic model is also able to simulate different types of motor deficits such as Parkinson’s disease only by manipulating the value of chaotic parameter. Our model has extensively examined in complexity and chaotic behavior using different analytical methods such as fractal dimension, bifurcation and largest Lyapunov exponent, and it was compared with conventional passive models and the stride signal of healthy subjects and Parkinson patients. 相似文献
80.