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951.
The problem of segregation of a two-phase multicomponent mixture under the action of thermal gradient, gravity and capillary forces is studied with respect to component distribution in a thick oil-gas-condensate reservoir. Governing equations are derived on the basis of nonequilibrium thermodynamics. A steady state of the two-phase mixture with nonzero diffusion fluxes and exchange between phases is described. In the case of binary mixtures analytical formulae for saturation, component distribution and flow in the two-phase zone are obtained. 相似文献
952.
Fuel migration in a water flowing through a porous medium generally occurs parallel to porous strata, which may not be horizontal. In this case, gravity tends to cause vertical segregation of fluids, depending on their densities. This phenomenon can exert a strong effect on fuel migration. The gravitational force creates the buoyancy force which acts upon the fuel, and may be either parallel or anti-parallel to the water flow direction.In this study, the above effects are investigated using the one-dimensional model of Pistineret al. We go beyond the latter investigation in describing the influence of the gravitational forces upon the movement of fuel saturation fronts in a vertical porous layer against and along the water flow direction.It is found that when the directions of the buoyancy force and of the water flow are anti-parallel, fuel migrates in the direction of the buoyancy force, provided the latter is strong enough. However, in the case of a weak buoyancy force, the direction of migration of the fuel depends on its mass. Small fuel masses move mainly in the direction of the water flow. However, big fuel slugs possessing large masses will move mainly in the direction of the buoyancy force. Slugs, characterized by intermediate masses, have no preferable moving direction and are almost stagnant. 相似文献
953.
A. A. Shapiro P. G. Bedrikovetsky A. Santos O. O. Medvedev 《Transport in Porous Media》2007,67(1):135-164
A population balance model for particulate suspension transport with capture of particles by porous medium accounting for
complete and incomplete plugging of pores by retained particles is derived. The model accounts for pore space accessibility,
due to restriction on finite size particle movement through the overall pore space, and for particle flux reduction, due to
transport of particles by the fraction of the overall flux. The novel feature of the model is the residual pore conductivity
after the particle retention in the pore and the possibility of one pore to capture several particles. A closed system of
governing stochastic equations determines the evolution of size distributions for suspended particles and pores. Its averaging
results in the closed system of hydrodynamic equations accounting for permeability and porosity reduction due to plugging.
The problem of deep bed filtration of a single particle size suspension through a single pore size medium where a pore can
be completely plugged by two particles allows for an exact analytical solution. The phenomenological deep bed filtration model
follows from the analytical solution. 相似文献
954.
Shock wave attenuation by grids and orifice plates 总被引:2,自引:0,他引:2
The interaction of weak shock waves with porous barriers of different geometries and porosities is examined. Installing a barrier inside the shock tube test section will cause the development of the following wave pattern upon a head-on collision between the incident shock wave and the barrier: a reflected shock from the barrier and a transmitted shock propagating towards the shock tube end wall. Once the transmitted shock wave reaches the end wall it is reflected back towards the barrier. This is the beginning of multiple reflections between the barrier and the end wall. This full cycle of shock reflections/interactions resulting from the incident shock wave collision with the barrier can be studied in a single shock tube test. A one-dimensional (1D), inviscid flow model was proposed for simulating the flow resulting from the initial collision of the incident shock wave with the barrier. Fairly good agreement is found between experimental findings and simulations based on a 1D flow model. Based on obtained numerical and experimental findings an optimal design procedure for shock wave attenuator is suggested. The suggested attenuator may ensure the safety of the shelter’s ventilation systems. 相似文献
955.
S. A. Babin M. G. Stepanov D. V. Churkin D. A. Shapiro 《Journal of Experimental and Theoretical Physics》2004,98(5):953-959
We have measured the shape of the Autler-Townes doublet and the peak of electromagnetically induced transparency (EIT) under plasma conditions. We compare the experimental results with the calculated spectrum of the probe field of a three-level ArII Λ-scheme by taking into account Coulomb collisions. We show that the Coulomb broadening of the EIT peak is small (less than 40%), while the saturation resonance is broadened under the experimental conditions by a factor of 3. In contrast to the saturation resonance attributable to the Bennett dip in the velocity distribution of the population, the EIT peak is a coherent effect and is broadened mainly through Coulomb dephasing. 相似文献
956.
The arguments of Cannon, Floyd, Grayson and Thurston (Geom. Dedicata (1989), 291–300) showing that solvegeometry groups are not almost convex apply to solvable Baumslag-Solitar groups. 相似文献
957.
Klaus G. Fischer Walter Morris Jay Shapiro 《Linear algebra and its applications》1998,270(1-3):191-214
We characterize the class of matrices for which the set of supports of nonnegative vectors in the null space can be determined by the signs of the entries of the matrix. This characterization is in terms of mixed dominating matrices, which are defined by the nonexistence of square submatrices that have nonzeros of opposite sign in each row. The class of mixed dominating matrices is contained in the class of L-matrices from the theory of sign-solvability, and generalizes the class of S-matrices. We give a polynomial-time algorithm to decide if a matrix is mixed dominating. We derive combinatorial conditions on the face lattice of a Gale transform of a matrix in this class. 相似文献
958.
B.I.Shapiro 《影像科学与光化学》2003,21(4)
本文研究了在卤化银光敏层的基础上构建多层CD盘的原理,研制了将影像中的银转化为产生荧光产物的方法,从而在应用荧光读取信息时可极大地提高其信噪比.研究后作者得出结论,传统的卤化银照相术能在制造多层光盘CDLROM中得到应用. 相似文献
959.
We prove a Gleason type theorem in the setting of functions hyperholomorphic in the unit ball of . We give an interpretation of the result in terms of pairs of functions defined in the unit ball of . Finally we use the theorem to study the homogeneous interpolation problem in the setting of hyperholomorphic functions. To cite this article: D. Alpay, M. Shapiro, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 889–894. 相似文献
960.
Alexander Shapiro 《Mathematical Methods of Operations Research》2003,58(1):57-68
We discuss in this paper statistical inference of sample average approximations of multistage stochastic programming problems. We show that any random sampling scheme provides a valid statistical lower bound for the optimal (minimum) value of the true problem. However, in order for such lower bound to be consistent one needs to employ the conditional sampling procedure. We also indicate that fixing a feasible first-stage solution and then solving the sampling approximation of the corresponding (T–1)-stage problem, does not give a valid statistical upper bound for the optimal value of the true problem.Supported, in part, by the National Science Foundation under grant DMS-0073770. 相似文献