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51.
Ashkan Babaie Arman Sadeghi Mohammad Hassan Saidi 《ournal of non Newtonian Fluid Mechanics》2011,166(14-15):792-798
Electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit is analyzed. After numerically solving the Poisson–Boltzmann equation, the momentum equation with electroosmotic body force is solved through an iterative numerical procedure for both favorable and adverse pressure gradients. The results reveal that, in case of pressure assisted flow, shear-thinning fluids reach higher velocity magnitudes compared with shear-thickening fluids, whereas the opposite is true when an adverse pressure gradient is applied. The Poiseuille number is found to be an increasing function of the dimensionless Debye–Hückel parameter, the wall zeta potential, and the flow behavior index. Comparison between the exact and the results based on the Debye–Hückel linearization reveals that the simplified solution leads to large errors in evaluating the velocity profile for zeta potentials higher than 25 mV, except for shear-thickening fluids in the presence of favorable pressure gradient. 相似文献
52.
Mona Sadeghi 《Theoretical and Experimental Chemistry》2010,46(2):132-137
An enzymatic degumming step in the production of edible soybean oil is carried out. The phosphatides are present in free hydratable
form (HP) or in nonhydratable form (NHP). The main characteristic of the discovery is the use of phospholipid A1 (Lecithin
Ultra) enzyme, which catalyzes reactions at specific temperatures. The mechanism includes the conversion of nonhydratable
phospholipids into water-soluble lysophospholipids, which are then removed by centrifuge, yielding degumming oil low in phosphorus.
The effects of important determining factors affecting oil degumming such as enzyme dosage, temperature and pH are investigated. 相似文献
53.
An efficient synthesis of aryliminophosphoranes is described. A mixture of an aromatic amine, diethyl azodicarboxylate and triphenylphosphine undergo a Mitsonobu type reaction at ambient temperature in dry dichloromethane to afford aryliminophosphoranes in excellent yields. 相似文献
54.
Babak Momeni Ehsan Shah Hosseini Murtaza Askari Mohammad Soltani Ali Adibi 《Optics Communications》2009,282(15):3168-697
A combination of negative refraction and diffraction compensation in a superprism-based photonic crystal structure is used to demonstrate a compact on-chip photonic crystal spectrometer. This structure provides strong dispersion and signal isolation, which are essential for forming an efficient and compact spectrometer. Performance of these spectrometers as spectral pattern detectors is discussed. The experimental results show that a PC structure with 80 μm × 220 μm dimension can locate a single spectral feature with better than 10 pm accuracy over a bandwidth of 50 nm around 1550 nm center wavelength at an output signal-to-noise ratio of 13 dB. 相似文献
55.
56.
Dikshitulu K. Kalluri Joo Hwa Lee Monzurul M. Ehsan 《International Journal of Infrared and Millimeter Waves》2003,24(3):349-365
This paper deals with the Finite Difference Time Domain (FDTD) simulation of interaction of an electromagnetic wave with a switched plasma slab. In formulating the simulation the well-known concepts of (a) total-field/scattered-field formulation (b) and PML lattice truncation are adapted to suit the simulation under consideration.FDTD is particularly well suited to handle the switched (time-varying) medium (including sudden switching) since the time varying parameters of the medium can be easily interpreted in the algorithm. The technique is applied to the difficult problem of interaction of an electromagnetic pulse source wave of frequency 0 and a gaussian envelope with a newly created plasma slab of time-varying and space varying electron density profile. The creation of a pulse of Wiggler magnetic field in the slab is illustrated. 相似文献
57.
In this paper, we study the braneworld scenarios in the presence of two real scalar fields coupled by gravity. The first-order formalism for the bent brane (for both de Sitter and anti-de Sitter geometry), leads us to discuss the shape invariance method in the bent brane systems. So, by using the fluctuations of metric and fields we obtain the Schrödinger equation. Then we factorize the corresponding Hamiltonian in terms of multiplication of the first-order differential operators. These first-order operators lead us to obtain the energy spectrum with the help of shape invariance method. 相似文献
58.
J. Sadeghi 《International Journal of Theoretical Physics》2007,46(3):492-502
We obtain the exact bound states of the generalized of Hulthén potential with negative energy levels using an analytic approach.
In order to obtain bound states, we use the associated Jacobi differential equation. Using the supersymmetry approach to quantum
mechanics, we show that these bound states, via four pairs of first order differential operators, represent four types of
ladder equations. Two types of these supersymmetric structures suggest derivation of algebric solutions for the bound states
using two different approaches.
PACS 21.60.Cs; 21.60.Fw; 21.60.-n; 03.65.Fd; 03.65.Ge; 03.65.-w 相似文献
59.
Mahdi Sadeghi Zahra Alipoor Abbas Majdabadi 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):745-751
The 82Sr/82Rb radionuclide generator is used very commonly in positron emission tomography. ALICE/ASH and TALYS 1.0 codes were used to calculate excitation functions for proton, alpha and 3He induced on various targets that lead to produce 82Sr radioisotope using intermediate energy accelerators. Recommended thickness of the targets according to SRIM code was premeditated. The application of those data, particularly in the calculation of integral yields, is discussed and theoretical integral yields for any reaction were computed. To consider precision of TALYS 1.0 code calculations, 85Rb(p,4n)82Sr process was determined as most interesting one due to radionuclide purity. The TALYS 1.0 code predicts a maximum cross-section of about 130 mb at 47 MeV for this reaction. Rubidium chloride deposition on copper substrate was carried out via sedimentation method in order to produce 82Sr. 2.98 g RbCl, 1.043 g ethyl cellulose, 10 mL acetone were used to prepare a layer of enriched rubidium chloride of 11.69 cm2 area and 0.34 g/cm2 thickness. 相似文献
60.
Masoud Darbandi Ehsan Roohi Vahab Mokarizadeh 《Numerical Methods for Partial Differential Equations》2008,24(2):583-604
The main objective of the current work is to introduce a new conceptual linearization strategy to improve the performance of a primitive shock‐capturing pressure‐based finite‐volume method. To avoid a spurious oscillatory solution in the chosen collocated grids, both the primitive and extended methods utilize two convecting and convected momentum expressions at each cell face. The expressions are obtained via a physical‐based discretization of two inclusive statements, which are constructed via a novel incorporation of the continuity and momentum governing equations. These two expressions in turn provide a strong coupling among the Euler conservative statements. Contrary to the primitive work, the linearization in the current work respects the definitions and essence of physics behind deriving the Euler governing equations. The accuracy and efficiency of the new formulation are then investigated by solving the shock tube as a problem with moving normal and expansion waves and the converging‐diverging nozzle as a problem with strong stationary normal shock. The results show that there is good improvement in performance of the primitive pressure‐based shock‐capturing method while its superior accuracy is not deteriorated at all. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008 相似文献