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81.
The nonlinear electrostatic drift waves are studied using quantum hydrodynamic model in dusty quantum magnetoplasmas. The dissipative effects due to collisions between ions and dust particles have also been taken into account. The Korteweg-de Vries Burgers (KdVB) like equation is derived and analytical solution is obtained using tanh method. The limiting cases of KdV type solitary waves, Burger type monotonic shock waves and oscillatory shock solutions are also presented. It is found that both hump and dip type solitary structures are possible in quantum dusty plasmas. However, amplitude and width of the nonlinear structure depend on the dust charge polarity and its concentration in electron-ion quantum plasmas. The monotonic shock like structure is independent of the quantum parameter. It is found that shock strength is increased in the presence of positively charged particles in comparison with negatively charged dust particles. The oscillatory shock structures are also obtained and it is found that change in dust charge polarity only shifts the phase of the oscillatory shock in plasmas. The numerical results are also presented for illustration. 相似文献
82.
Li H Haque SA Kitaygorodskiy A Meziani MJ Torres-Castillo M Sun YP 《Organic letters》2006,8(24):5641-5643
It was found that the C60 hexakis-adduct (Th) bearing 12 electron-donating N,N-dimethylaniline moieties could not be synthesized by the Bingel-Hirsch method with either classical or deviated experimental parameters in a one-pot reaction. A different modification to the original Bingel reaction without the use of any templating agent was necessary for high-yield synthesis of the compound. The generalization of this alternatively modified Bingel method to the preparation of other C60 hexakis-adducts is demonstrated. [structure: see text]. 相似文献
83.
Joelle M. Onorato Luping Chen Petia Shipkova Zhengping Ma Anthony V. Azzara James J. Devenny Ningning Liang Tasir S. Haque Dong Cheng 《Analytical and bioanalytical chemistry》2010,397(7):3137-3142
The formation of malonyl-CoA is catalyzed by acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of de novo fatty acid
synthesis. Monitoring the changes of malonyl-CoA concentration in the brain in response to treatments such as pharmaceutical
intervention (via ACC inhibitors) or different dietary conditions (such as varied feeding regimes) is of great interest and
could help increase the understanding of how this molecule contributes to feeding behavior and overall energy balance. We
have developed a sensitive analytical method for the determination of malonyl-CoA levels in rat brain tissue. The assay involved
removal of tissue lipids by liquid-liquid extraction followed by LC/MS/MS analysis of the aqueous layer for malonyl-CoA. The
method was sensitive enough (limit of quantitation = 50 ng/mL, or approximately 0.018 nmol/g brain tissue) to determine malonyl-CoA
in individual rat brain preparations. The assay performance was sufficiently rugged to support drug discovery screening efforts
and provided an additional analytical tool for monitoring brain malonyl-CoA levels. 相似文献
84.
Farooq Umar Hossein Raza Hamdani Anwar‐ul‐Haque Sajid Raza Chaudhry Khalid Parvez 《国际流体数值方法杂志》2009,59(2):173-194
The effect of various reduced frequencies has been examined for an oscillating aspect ratio 10 NACA 0015 wing. An unsteady, compressible three‐dimensional (3D) Navier–Stokes code based on Beam and Warming algorithm with the Baldwin–Lomax turbulence model has been used. The code is validated for the study against published experimental data. The 3D unsteady flow field is simulated for reduced frequency values of 0.1, 0.2 and 0.3 for a fixed mean angle of attack position and fixed amplitude. The type of motion is sinusoidal harmonic. The force coefficients, pressure distributions and flow visualization show that at the given conditions the flow remains attached to the wing surface even at high angles of attack with no clear separation or typical light‐to‐deep category of dynamic stall. Increased magnitude of hysteresis and higher gradients are seen at higher reduced frequencies. The 3D effects are even found at midspan locations. In addition, the rate of decrease in lift near the wing tips compared with the wing root is not much like in the static cases. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
85.
Hsiao-Fang Lee Benedict A. Samuel M. A. Haque 《Journal of Thermal Analysis and Calorimetry》2010,99(2):495-500
We present a new analytical model for thermal conductivity measurement of one-dimensional nanostructures on substrates. The
model expands the capability of the conventional 3ω technique, to make it versatile with both in and out of plane thermal
conductivity measurement on specimens either freestanding or attached to substrates. We demonstrate the model on both conducting
(aluminum) and semi-conducting (focused ion beam deposited platinum) specimens. The agreement with the established values
in the literature suggests the superiority of this technique in terms of convenience and robustness of measurement. 相似文献
86.
87.
Control of charge recombination dynamics in dye sensitized solar cells by the use of conformally deposited metal oxide blocking layers 总被引:8,自引:0,他引:8
Palomares E Clifford JN Haque SA Lutz T Durrant JR 《Journal of the American Chemical Society》2003,125(2):475-482
We report herein a methodology for conformally coating nanocrystalline TiO2 films with a thin overlayer of a second metal oxide. SiO2, Al2O3, and ZrO2 overlayers were fabricated by dipping mesoporous, nanocrystalline TiO2 films in organic solutions of their respective alkoxides, followed by sintering at 435 degrees C. These three metal oxide overlayers are shown in all cases to act as barrier layers for interfacial electron transfer processes. However, experimental measurements of film electron density and interfacial charge recombination dynamics under applied negative bias were vary significantly for the overlayers. A good correlation was observed between these observations and the point of zero charge of the different metal oxides. On this basis, it is found that the most basic overlayer coating, Al2O3 (pzc = 9.2), is optimal for retarding interfacial recombination losses under negative applied bias. These observations show good correlation with current/voltage analyses of dye sensitized solar cell fabricated from these films, with the Al2O3 resulting in an increase in V(oc) of up to 50 mV and a 35% improvement in overall device efficiency. These observations are discussed and compared with an alternative TiCl4 posttreatment of nanocrystalline TiO2 films with regard to optimizing device efficiency. 相似文献
88.
The spot-test for m-dinitroaromatics and their derivatives, based on the Janovsky reaction, is re-investigated. The sensitivity of the spot-test has been much enhanced by changing the solvent and using the novel “pellet” spot-test. With the “pellet” spot-test and dimethylsulphoxide, 4–50 ng of m-dinitroaromatic compounds and their derivatives can be detected. The change from acetone (used in the original spot-test) to dimethylsulphoxide changes the reaction product in most cases. 相似文献
89.
The gaseous equilibria involving the molecules AuSi, AuSi2 and Au2Si have been studied by means of the Knudsen effusion technique combined with mass spectrometric analysis of the vapor. The experimentally determined reaction enthalpies were combined with appropriate literature data to obtain the following atomization energies (in kJ mole−1): D00[AuSi(g)] = 301.0 ± 6.0, D00[Au2Si(g)] = 582.7 ± 15 and D00[AuSi2(g)] = 602.1 ± 15. The corresponding D0298 values are: 305.2 ± 6.0, 589.1 ± 15 and 610.5 ± 15, and the standard heats of formation, ΔH0f,298, 518.6, 602.9 and 668.9, respectively.
Comparison of the atomization energies of these silicon—gold molecules with the literature values for the corresponding germanium—gold and tin—gold molecules indicates similarity in the nature of bonding. 相似文献
90.
A kinetic spectrophotometric method has been described for the determination of metoprolol tartrate in commercial dosage forms. The procedure is based on the reaction of the drug with 1‐chloro‐2, 4‐dinitrobenzene (CDNB) in dimethylsulfoxide (DMSO) at 100 ± 1 °C. The reaction is investigated by measuring the change in absorbance with time at 420 nm. Fixed‐time (ΔA) and equilibrium methods are chosen for obtaining the calibration curves. Both calibration curves were found to be linear over the concentration range of 5‐60 μg mL?1. The regression analysis of calibration data resulted in the linear regression equations of ΔA = ?1.608 × 10?4 + 3.96 × 10?3 C and A = 7.31 × 10?4 + 1.90 × 10?2 C for fixed time (ΔA) and equilibrium methods, respectively. The limit of detection (LOD) for fixed time and equilibrium methods are 1.16 and 0.415 μg mL?1, respectively. The method has been successfully applied to the quantitation of metoprolol tartrate in commercial dosage forms. Statistical comparison of the results shows that there is no significant difference between the proposed methods and El‐Ries's spectrophotometric method. 相似文献