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991.
I. M. Troyanova V. A. Tupchiev 《Computational Mathematics and Mathematical Physics》2009,49(7):1151-1166
For the problem of a strong point explosion with cylindrical symmetry, high-order asymptotic expansions of the solution with respect to the viscosity and thermal conductivity are constructed and justified. 相似文献
992.
应用高速摄像仪对液体的爆炸分散实验过程进行了拍摄,得到了液体爆炸分散过程的时间序列.通过对灰度图像分形维数的分析,揭示了液体爆炸分散过程的机理. 相似文献
993.
Tian Ma & Shouhong Wang 《数学研究》2014,47(4):305-378
First, the essence of a physical theory for a multilevel system is through
coupling different physical laws in different levels by a symmetry-breaking principle,
rather than through a unification using larger symmetry. In astrophysical dynamics,
the symmetry-breaking mechanism and the coupling are achieved by prescribing the
coordinate system so that the laws of fluid dynamics and heat conductivity are coupled
with gravitational field equations. Another important ingredient in modeling fluid
motion in astrophysics is to use the momentum density field to replace the velocity
field as the state function of cosmic objects. Second, by applying the new symmetry-breaking
mechanism and the new coupled astrophysical dynamics model, we rigorously
prove a basic theorem on black holes: Assume the validity of the Einstein theory
of general relativity, then black holes are closed, innate and incompressible. Third, we
prove a theorem on structure of universes. Assume the Einstein theory of general relativity,
and the principle of cosmological principle that the universe is homogeneous
and isotropic. Then we show that 1) all universes are bounded, are not originated from
a Big-Bang, and are static; and 2) The topological structure of our Universe can only
be the 3D sphere. Also, thanks to the basic properties of black holes, we show that our
results on our Universe resolve such fundamental problems as dark matter and dark
energy, redshifts and CMB. Fourth, we discovered that both supernovae explosion and AGN jets, as well as many astronomical
phenomena, are due to combined relativistic, magnetic and thermal effects.
The radial temperature gradient causes vertical Bénard convection cells, and the relativistic
viscous force (via electromagnetic, the weak and the strong interactions) gives
rise to an huge explosive radial force near the Schwarzschild radius, leading e.g. to
supernovae explosion and AGN jets. 相似文献
994.
有氧化剂(AP)含铝炸药的爆轰性能 总被引:4,自引:1,他引:3
对有氧化剂含铝炸药(RDX/AP/Al/粘合剂=20/43/25/12,下称含铝炸药)爆轰反应的点火增长模型进行研究。用VLW状态方程方法计算了含铝炸药爆轰产物JWL状态方程;用激光速度干涉仪(VISAR)测量炸药/窗口界面粒子速度和炸药驱动金属平板自由表面速度,对试验进行了数值模拟计算,拟合了含铝炸药的反应速率方程。研究结果表明,用VLW状态方程方法和炸药/窗口界面粒子速度确定JWL状态方程和反应速率方程可行,金属平板驱动试验的计算结果与试验结果吻合。 相似文献
995.
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详细分析了测量任意反射面的激光干涉测速系统(VISAR)中信号光纤的模式色散对速度测量的影响,建立了数学分析模型,数值模拟了色散对比度因子与测速系统所使用的条纹常数和被测速度增量之间的关系。研究结果表明:(1)测速时使用的条纹常数越大,信号光纤模式色散的影响越小;(2)被测速度越大,信号光纤模式色散的影响越大;(3)阶跃折射率光纤的色散影响比剃度折射率光纤大得多。通过本项研究,给出了减小信号光纤模式色散的有效措施,对提高VISAR的干涉图对比度及测试精确度具有重要作用。 相似文献
999.
The predominant deformation mode during material failure is shear. In this paper, a crystal plasticity scheme for explicit time integration codes is developed based on a forward Euler algorithm. The numerical model is incorporated in the UMAT subroutine for implementing rate-dependent crystal plasticity model in LS-DYNA/Explicit. The sheet is modeled as a face centered cubic (FCC) polycrystalline aggregate, and a finite element analysis based on rate-dependent crystal plasticity is implemented to analyze the effects of three different strain paths consisting predominantly of shear. Finite element meshes containing texture data are created with solid elements. The material model can incorporate information obtained from electron backscatter diffraction (EBSD) and apply crystal orientation to each element as well as account for texture evolution. Single elements or multiple elements are used to represent each grain within a microstructure. The three dimensional (3D) polycrystalline microstructure of the aluminum alloy AA5754 is modeled and subjected to three different strain rates for each strain path. The effects of strain paths, strain rates and thermal softening on the formation of localized deformation are investigated. Simulations show that strain path is the most dominant factor in localized deformation and texture evolution. 相似文献
1000.