全文获取类型
收费全文 | 87032篇 |
免费 | 7792篇 |
国内免费 | 9235篇 |
专业分类
化学 | 32686篇 |
晶体学 | 365篇 |
力学 | 8207篇 |
综合类 | 1371篇 |
数学 | 31674篇 |
物理学 | 29756篇 |
出版年
2023年 | 750篇 |
2022年 | 1163篇 |
2021年 | 1590篇 |
2020年 | 1960篇 |
2019年 | 2135篇 |
2018年 | 1891篇 |
2017年 | 2226篇 |
2016年 | 2557篇 |
2015年 | 2323篇 |
2014年 | 3344篇 |
2013年 | 6151篇 |
2012年 | 3826篇 |
2011年 | 4412篇 |
2010年 | 3675篇 |
2009年 | 5103篇 |
2008年 | 5589篇 |
2007年 | 5797篇 |
2006年 | 5301篇 |
2005年 | 4506篇 |
2004年 | 4012篇 |
2003年 | 4004篇 |
2002年 | 3492篇 |
2001年 | 2972篇 |
2000年 | 2866篇 |
1999年 | 2559篇 |
1998年 | 2362篇 |
1997年 | 1948篇 |
1996年 | 1679篇 |
1995年 | 1605篇 |
1994年 | 1464篇 |
1993年 | 1271篇 |
1992年 | 1200篇 |
1991年 | 957篇 |
1990年 | 823篇 |
1989年 | 720篇 |
1988年 | 653篇 |
1987年 | 524篇 |
1986年 | 450篇 |
1985年 | 520篇 |
1984年 | 513篇 |
1983年 | 245篇 |
1982年 | 402篇 |
1981年 | 459篇 |
1980年 | 344篇 |
1979年 | 345篇 |
1978年 | 274篇 |
1977年 | 266篇 |
1976年 | 206篇 |
1974年 | 129篇 |
1973年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Viscous waves and waves over a submerged cylinder in a stationary tank are simulated using a volume-of-fluid numerical scheme on adaptive hierarchical grids. A high resolution interface-capturing method is used to advect the free surface interface and the Navier–Stokes equations are discretised using finite volumes with collocated primitive variables and solved using a Pressure Implicit with Splitting of Operators (PISO) algorithm. The cylinder is modelled by using the technique of Cartesian cut cells. Results of flow of a single fluid past a cylinder at Reynolds number Re=100 are presented and found to agree well with experimental and other numerical data. Viscous free surface waves in a tank are simulated using uniform and quadtree grids for Reynolds numbers in the range from 2 to 2000, and the results compared against analytical solutions where available. The quadtree-based results are of the same accuracy as those on the equivalent uniform grids, and retain a sharp interface at the free surface while leading to considerable savings in both storage and CPU requirements. The nonlinearity in the wave is investigated for a selection of initial wave amplitudes. A submerged cylinder is positioned in the tank and its influence on the waves as well as the hydrodynamic loading on the cylinder is investigated. 相似文献
992.
993.
A parametric study of droplet deformation through a microfluidic contraction: Shear thinning liquids
D.J.E. Harvie M.R. Davidson J.J. Cooper-White M. Rudman 《International Journal of Multiphase Flow》2007
Numerical simulations of a droplet passing through an axisymmetric microfluidic contraction are presented, focusing on systems where one of the two liquids present is shear thinning. The simulations are performed using a transient Volume of Fluid (VOF) algorithm. When the droplet is shear thinning and the surrounding phase Newtonian, droplets deform in a similar way to Newtonian droplets that have a viscosity equal to the average viscosity of the shear thinning fluid while it is within the contraction. When the surrounding phase is shear thinning and the droplet Newtonian, droplets deform in a similar way to droplets contained within a Newtonian liquid that has a viscosity that is lower than that of the droplet. In both cases the behaviour of the shear thinning fluid can be broadly described in terms of a ‘characteristic’ Newtonian viscosity: However, determining the exact value of this viscosity without performing a full shear thinning simulation is not possible. 相似文献
994.
995.
José Rául Quintero 《Journal of Dynamics and Differential Equations》2003,15(1):125-142
We study nonlinear orbital stability and instability of the set of ground state solitary wave solutions of a one-dimensional Boussinesq equation or one-dimensional Benney–Luke equation. It is shown that a solitary wave (traveling wave with finite energy) may be orbitally stable or unstable depending on the range of the wave's speed of propagation. 相似文献
996.
997.
998.
The stress vector-based constitutive model for cohesionless soil, proposed by SHI Hong-yan et al., was applied to analyze
the deformation behaviors of materials subjected to various stress paths. The result of analysis shows that the constitutive
model can capture well the main deformation behavior of cohesionless soil, such as stress-strain nonlinearity, hardening property,
dilatancy, stress path dependency, non-coaxiality between the principal stress and the principal strain increment directions,
and the coupling of mean effective and deviatoric stress with deformation. In addition, the model can also take into account
the rotation of principal stress axes and the influence of intermediate principal stress on deformation and strength of soil
simultaneously. The excellent agreement between the predicted and measured behavior indicates the comprehensive applicability
of the model.
Biography: SHI Hong-yan (1962-), Associate Professor, Doctor 相似文献
999.
Some conclusions about the smooth function classes stability for the basic system of equations of atmospheric motion and instability for Navier-Stokes equation are summarized. On the basis of this, by taking the basic system of equations of atmospheric motion via Boussinesq approximation as example to explain in detail that the instability about some simplified models of the basic system of equations for atmospheric motion is caused by the instability of Navier-Stokes equation, thereby, a principle to guarantee the stability of simplified equation is drawn in simplifying the basic system of equations. 相似文献
1000.
The stationary and time-dependent aerodynamic coefficients of a slender blunt cone with a flap located near the base section of the model are experimentally investigated. The freestream parameters (M∞ = 6, Re L = 0.88 × 107, and γ = 1.4) ensured a turbulent regime of flow over the conical surface and the flap. At high angles of attack (α ~ 10°) laminar-turbulent transition is observable in the separation zone on the leeward side of the body. Emphasis is placed on the determination of the trimming angles of attack for different positions of the center of rotation and the static and dynamic stability coefficients (the model oscillation damping coefficient). 相似文献