全文获取类型
收费全文 | 5961篇 |
免费 | 1052篇 |
国内免费 | 775篇 |
专业分类
化学 | 4076篇 |
晶体学 | 42篇 |
力学 | 444篇 |
综合类 | 33篇 |
数学 | 753篇 |
物理学 | 2440篇 |
出版年
2024年 | 3篇 |
2023年 | 127篇 |
2022年 | 106篇 |
2021年 | 162篇 |
2020年 | 219篇 |
2019年 | 235篇 |
2018年 | 173篇 |
2017年 | 179篇 |
2016年 | 264篇 |
2015年 | 290篇 |
2014年 | 292篇 |
2013年 | 357篇 |
2012年 | 531篇 |
2011年 | 595篇 |
2010年 | 399篇 |
2009年 | 319篇 |
2008年 | 421篇 |
2007年 | 376篇 |
2006年 | 358篇 |
2005年 | 333篇 |
2004年 | 281篇 |
2003年 | 196篇 |
2002年 | 164篇 |
2001年 | 140篇 |
2000年 | 106篇 |
1999年 | 139篇 |
1998年 | 102篇 |
1997年 | 115篇 |
1996年 | 118篇 |
1995年 | 116篇 |
1994年 | 82篇 |
1993年 | 67篇 |
1992年 | 58篇 |
1991年 | 65篇 |
1990年 | 67篇 |
1989年 | 53篇 |
1988年 | 41篇 |
1987年 | 27篇 |
1986年 | 34篇 |
1985年 | 27篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有7788条查询结果,搜索用时 140 毫秒
101.
本文提出一种用高密度位相型闪耀光栅测取板的曲率和斜率的单光束错位云纹干涉法,由于这一方法具有高灵敏度。大量程和高反差的优点。可有效地用来求解板的弯曲问题。文中还给出了周边固定圆板和带缺口的方板两个应用实例。 相似文献
102.
Dai Tian-min 《应用数学和力学(英文版)》2003,24(10):1134-1140
The existing various couple stress theories have been carefully restudied.The purpose is to propose a coupled Noether’s theorem and to reestablish rather complete conservation laws and balance equations for couple stress elastodynamics. The new concrete forms of various conservation laws of couple stress elasticity are derived. The precise nature of these conservation laws which result from the given invariance requirements are established. Various special cases are reduced and the results of micropolar continua may be naturally transited from the results presented in this paper. 相似文献
103.
Some experiments were made for the buoyant jet from a square orifice with a square disc placed on it in static ambient and concentration along the axis in self-similar area behind disc was measured. And at the same time a three-dimensional mathematical model was established to simulate the whole flowing under different conditions. All the results predicted by the numerical calculation were substantiated by the experiments. The results were compared with experiential formula for obstructed round buoyant vertical jets in static ambient and it was found that the two concentration distributions had good accordance. Star shape of temperature isolines on cross-sections in the near areas from the disc was found and it was a very special figure for obstructed square buoyant vertical jets with a square disc. The shape will transform to concentric circles gradually alike to the round buoyant vertical jet in self-similar area with increasing of the distance from the disc. 相似文献
104.
105.
106.
板的非线性热弹耦合振动(Ⅰ):近似解析解 总被引:4,自引:0,他引:4
本文以文[2,3,4]为基础,导出了板的热弹耦合非线性振动控制方程,在采用Galerkin法离散化以后,按各个变量性质分别用多尺度法或正则摄动法求得近似解析解。籍此可揭示系统各参数对非线性热弹耦合振动影响的机理和作出必要的近似计算,对工程实际具有较大的参考价值。 相似文献
107.
For axially symmetric deformations of the perfectly elastic neo-Hookean and Mooney materials, formal series solutions are
determined in terms of expansions in appropriate powers of 1/R, where R is the cylindrical polar coordinate for the material coordinates. Remarkably, for both the neo-Hookean and Mooney materials,
the first three terms of such expansions can be completely determined analytically in terms of elementary integrals. From
the incompressibility condition and the equilibrium equations, the six unknown deformation functions, appearing in the first
three terms can be reduced to five formal integrations involving in total seven arbitrary constants A, B, C, D, E, H and k
2, and a further five integration constants, making a total of 12 integration constants for the deformation field. The solutions
obtained for the neo-Hookean material are applied to the problem of the axial compression of a cylindrical rubber tube which
has bonded metal end-plates. The solution so determined is approximate in two senses; namely as an approximate solution of
the governing equations and for which the stress free and displacement boundary conditions are satisfied in an average manner
only. The resulting load-deflection relation is shown graphically. The solution so determined, although approximate, attempts
to solve a problem not previously tackled in the literature.
相似文献
108.
Hole-drilling method is one of the most convenient methods for engineering residual stress measurement. Combined with moiré
interferometry to obtain the relaxed whole-field displacement data, hole-drilling technique can be used to solve non-uniform
residual stress problems, both in-depth and in-plane. In this paper, the theory of moiré interferometry and incremental hole-drilling
(MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by
ABAQUS to obtain the coefficients for the residual stress calculation. An experimental system including real-time measurement,
automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual
stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented.
Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements.
The project supported by the FRAMATOME ANP 相似文献
109.
Exact travelling-wave solutions of an integrable equation arising in hyperelastic rods 总被引:1,自引:0,他引:1
H.-H. Dai 《Wave Motion》1998,28(4):367-381
In this paper, we study an integrable nonlinear evolution equation which arises in the context of nonlinear dispersive waves in hyperelastic rods. To consider bounded travelling-wave solutions, we conduct a phase plane analysis. A new feature is that there is a vertical singular line in the phase plane. By considering equilibrium points and the relative position of the singular line, we find that there are in total three types of phase planes. The trajectories which represent bounded travelling-wave solutions are studied one by one. In total, we find there are 12 types of bounded travelling waves, both supersonic and subsonic. While in literature solutions for only two types of travelling waves are known, here we provide explicit solution expressions for all 12 types of travelling waves. Also, it is noted for the first time that peakons can have applications in a real physical problem. 相似文献
110.
将零厚度单向试件栅刻蚀工艺应用于晶须增韧氮化硅陶瓷基复合材料表面,通过记录试件所在桥路的输出电压值,可得到随载荷不断增大裂纹逐渐向前扩展过程中每一时刻的裂尖位置和裂纹长度,从而得到该种材料的阻力曲线。 相似文献