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191.
Eulerian-Eulerian two-phase numerical simulation of nanofluid laminar forced convection in a microchannel 总被引:1,自引:0,他引:1
Mohammad Kalteh Abbas Abbassi Majid Saffar-AvvalJens Harting 《International Journal of Heat and Fluid Flow》2011,32(1):107-116
In this paper, laminar forced convection heat transfer of a copper-water nanofluid inside an isothermally heated microchannel is studied numerically. An Eulerian two-fluid model is considered to simulate the nanofluid flow inside the microchannel and the governing mass, momentum and energy equations for both phases are solved using the finite volume method. For the first time, the detailed study of the relative velocity and temperature of the phases are presented and it has been observed that the relative velocity and temperature between the phases is very small and negligible and the nanoparticle concentration distribution is uniform. However, the two-phase modeling results show higher heat transfer enhancement in comparison to the homogeneous single-phase model. Also, the heat transfer enhancement increases with increase in Reynolds number and nanoparticle volume concentration as well as with decrease in the nanoparticle diameter, while the pressure drop increases only slightly. 相似文献
192.
Steady and pulsatile flow and heat transfer in a channel lined with two porous layers subject to constant wall heat flux under
local thermal non-equilibrium (LTNE) condition is numerically investigated. To do this, a physical boundary condition in the
interface of porous media and clear region of the channel is derived. The objective of this work is, first, to assess the
effects of local solid-to-fluid heat transfer (a criterion indicating on departure from local thermal equilibrium (LTE) condition),
solid-to-fluid thermal conductivity ratio and porous layer thickness on convective heat transfer in steady condition inside
a channel partially filled with porous media; second, to examine the impact of pulsatile flow on heat transfer in the same
channel. The effects of LTNE condition and thermal conductivity ratio in pulsatile flow are also briefly discussed. It is
observed that Nusselt number inside the channel increases when the problem is tending to LTE condition. Therefore, careless
consideration of LTE may lead to overestimation of heat transfer. Solid-to-fluid thermal conductivity ratio is also shown
to enhance heat transfer in constant porous media thickness. It is also revealed that an increase in the amplitude of pulsation
may result in enhancement of Nusselt number, while Nusselt number has a minimum in a certain frequency for each value of amplitude. 相似文献
193.
Seifollah Jalili Arezou Jaberi Mohammad Ghasem Mahjani Majid Jafarian 《Molecular physics》2013,111(6):361-368
Utilising molecular dynamics simulations, the hydrogen molecules adsorption isotherms of the (8,?0) palladium decorated single-walled carbon nanotube (SWNT) were obtained. The hydrogen adsorption was studied on the external, interstial and internal surfaces of the SWNT bundle at several temperatures ranging from 77 to 400?K. The results were compared with the bare single-walled carbon nanotube bundle under the same conditions. The decorated carbon nanotube bundle hydrogen adsorption was significantly higher than that of the bare one. The hydrogen desorption and readsorption were studied using temperature as the readsorption/desorption variable. The rate constants were calculated for the hydrogen desorption at different temperatures. The calculated decorated SWNT bundle hydrogen desorption activation energy was higher than that for the bare SWNT bundle. The calculated activation energies for the hydrogen desorption in both nanotube bundles specified the temperature dependency of hydrogen desorption. 相似文献
194.
Hamid R. Memarian Majid M. Sadeghi Ahmad R. Momeni Dietrich D?pp 《Monatshefte für Chemie / Chemical Monthly》2002,9(4):661-667
Some novel 3,5-diacetyl-1,4-dihydropyridine derivatives were synthesized; their photochemical behaviour was studied under oxygen or argon atmosphere. Irradiation of these compounds resulted in the aromatization of the ring and formation of 3,5-diacetylpyridine derivatives. The presence of oxygen plays an important role in the type, rate, or failure of oxidation. Irradiation of these compounds with of 2-furyl or 5-methyl-2-furyl substituents in position 4 under argon resulted in the formation of a pyridine ring with retention of these substituents, whereas loss of these substituents and ring aromatization was observed upon irradiation under oxygen. 相似文献
195.
The Publishers W.H. Abd. Majid 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):575
In spite of the precautions taken to check the originality of the articles,
it happens, unfortunately that our scientific colleagues' vigilance is sometimes caught up unprepared.
Today, it has come to our attention that
the following article results from a plagiarism.
We apologize to the authors who suffered from it.
You will
find hereafter a note written by Dr Majid which summarizes the situation. 相似文献
196.
Majid M. Heravi Fatemeh Derikvand Masoumeh Haghighi 《Monatshefte für Chemie / Chemical Monthly》2008,139(1):31-33
Summary. An efficient and improved procedure for the synthesis of tetrasubstituted imidazoles by FeCl3 · 6H2O catalyzed four-component one-pot synthesis in refluxing ethanol is described. 相似文献
197.
198.
Majid Moghadam Iraj Mohammadpoor-Baltork Valiollah Mirkhani Shahram Tangestaninejad Mohammad Abdollahi-Alibeik Behrooz H. Yousefi Hadi Kargar 《Monatshefte für Chemie / Chemical Monthly》2007,33(3):579-583
Small assemblies of 2-imidazolines and bisimidazolines from appropriate nitriles and ethylenediamine with catalytic amounts
of P2S5 employing a microwave assisted protocol were prepared. Sonication of this system also led to successful synthesis of 2-imidazolines
and bisimidazolines. Another advantage of these systems is the ability to carry out large scale reactions. 相似文献
199.
The progress of the compaction process to produce from an assembly of particles a coherent mass can be achieved by the application of shear and normal stress. The achievement of a densified coherent mass necessitates, together with the yielding of material, the movement of particles over and between each other. In uniaxial compaction the angle of internal friction, δE, is a projection of the unique critical state line which divides a three dimensional relationship between volume change (V), shear stress (?) and normal stress (σ) into yield domains and surfaces. There is one region for failure and flow (the Hvorslev surface) and another region for failure and consolidation (the Roscoe surface). In this paper the concepts of the Roscoe and Hvorslev surfaces together with the Coulomb yield criterion have been applied to the uniaxial compaction, over a range of compactable stresses, of titanium dioxide (20–2000 kPa). The characteristics of applied and shear stress, angle of internal friction (δE), angle of shearing resistance (?) and surface area (SBET) were measured and correlated with the compaction stress (σc) and diametral strength (σf) of the compacts to investigate the phenomena of uniaxial compaction. 相似文献
200.
It is known that the classical capillary pressure-saturation relationship may be deficient under non-equilibrium conditions when large saturation changes may occur. An extended relationship has been proposed in the literature which correlates the rate of change of saturation to the difference between the phase pressures and the equilibrium capillary pressure. This linear relationship contains a damping coefficient, \tau, that may be a function of saturation. The extended relationship is examined at the macro-scale through simulations using the two-phase simulator MUFTE-UG. In these simulations, it is assumed that the traditional equilibrium relationship between the water saturation and the difference in fluid pressures holds locally. Steady-state and dynamic numerical experiments are performed where a non-wetting phase displaces a wetting phase in homogeneous and heterogeneous domains with varying boundary conditions, domain size, and soil parameters. From these simulations the damping coefficient can be identified as a (non-linear) function of the water saturation. It is shown that the value of increases with an increased domain size and/or with decreased intrinsic permeability. Also, the value of for a domain with a spatially correlated random distribution of intrinsic permeability is compared to a homogeneous domain with equivalent permeability; they are shown to be almost equal. 相似文献