全文获取类型
收费全文 | 2758篇 |
免费 | 289篇 |
国内免费 | 90篇 |
专业分类
化学 | 213篇 |
晶体学 | 11篇 |
力学 | 1549篇 |
综合类 | 34篇 |
数学 | 472篇 |
物理学 | 858篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 42篇 |
2021年 | 37篇 |
2020年 | 58篇 |
2019年 | 45篇 |
2018年 | 42篇 |
2017年 | 62篇 |
2016年 | 94篇 |
2015年 | 63篇 |
2014年 | 128篇 |
2013年 | 123篇 |
2012年 | 116篇 |
2011年 | 156篇 |
2010年 | 94篇 |
2009年 | 147篇 |
2008年 | 159篇 |
2007年 | 184篇 |
2006年 | 167篇 |
2005年 | 154篇 |
2004年 | 124篇 |
2003年 | 128篇 |
2002年 | 95篇 |
2001年 | 76篇 |
2000年 | 82篇 |
1999年 | 75篇 |
1998年 | 95篇 |
1997年 | 85篇 |
1996年 | 62篇 |
1995年 | 60篇 |
1994年 | 59篇 |
1993年 | 48篇 |
1992年 | 56篇 |
1991年 | 50篇 |
1990年 | 53篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1957年 | 2篇 |
排序方式: 共有3137条查询结果,搜索用时 109 毫秒
91.
I. F. Kirichok 《International Applied Mechanics》2006,42(3):336-341
The forced flexural vibrations and dissipative heating of a bimorph ring plate are studied. The plate is made of viscoelastic
piezoceramics and is polarized across the thickness. The outer surfaces of the plate are nonuniformly electroded, and harmonic
electric excitation is applied to the electrodes. The viscoelastic behavior of the material is described using the concept
of temperature-dependent complex moduli. The coupled nonlinear problem of thermoviscoelasticity is solved by time iteration
using, at each iteration, the discrete-orthogonalization method to integrate the mechanics equations and the explicit finite-difference
method to solve the heat-conduction equation with a nonlinear heat source. Numerical calculations demonstrate that by changing
the size of the ring electrode we can influence the natural frequency, stress and displacement distributions, dissipative-heating
temperature, and amplitude-and temperature-frequency characteristics. With certain boundary conditions, there is an optimal
electrode configuration that produces deflections of maximum amplitudes when an electric excitation is applied
__________
Translated from Prikladnaya Mekhanika, Vol. 42, No. 3, pp. 102–109, March 2006. 相似文献
92.
93.
戴世强 《应用数学和力学(英文版)》1991,12(7):617-625
In this paper,we reexamine the method of successive approximation presented byProf.Chien Wei-zang for solving the problem of large deflection of a circular plate,and findthat the method could be regarded as the method of strained parameters in the singularperturbation theory.In terms of the parameter representing the ratio of the centerdeflection to the thickness of the plate,we make the asymptotic expansions of thedeflection,membrane stress and the parameter of load as in Ref.[1],and then give theorthogonality conditions(i.e.the solvability conditions)for the resulting equations,bywhich the stiffness characteristics of the plate could be determined.It is pointed out thatwith the solutions for the small deflection problem of the circular plate and theorthogonality conditions,we can derive the third order approximate relations between theparameter of load and the center deflection and the first-term approximation of membranestresses at the center and edge of the plate without solving the differential equ 相似文献
94.
本文给出一种二维矩形超级单元,用以分析平板网架结构,其做法是将大型平板网架结构离散成一系列矩形超级单元,考虑弯曲、剪切、挤压、拉压、翘曲等多种非经典变形效应,采用构件自由度向超级元自由度的转换把大型多构件问题的求解变为二维问题的求解,可大大减少未知量,又能保证精度,并可方便地与一般有限元软件连接。 相似文献
95.
Effects of oxidation and surface roughness on contact angle 总被引:1,自引:0,他引:1
Contact angle is known to be a parameter that effects boiling. This study was undertaken to measure contact angle of high and low surface tension fluids on copper and aluminum surfaces.Data were taken for polished, oxidized, and rough surfaces. A simple, yet fairly accurate method of measuring the static equilibrium contact angle of a solid/liquid interface is presented. The principles of a line light source and tilting plate were modified and then combined in the design of this apparatus. The angles obtained and their variation with the solid surface properties were in good agreement with previously published data. The contact angle of distilled water o of the organic fluids and refrigerants tested were in the range of 2–5°. Roughness and oxidation reduce the contact angle. If the depth of the roughness is less than 0.5 μm contact angle. The apparatus is fairly simple in construction, is inexpensive, and has good reproductibity. The measured angles were then compared to those measured with the sessile drop method. 相似文献
96.
97.
功能梯度矩形厚板的三维热弹性分析 总被引:6,自引:1,他引:6
直接从三维热弹性力学基本方程出发,通过引入两个位移函数和两个应力函数,导出了一个二阶的齐次状态方程和一个四阶的非齐次状态方程。分析中采用了层合近似模型,即将板划分成厚度足够小的若干薄层,从面可将每一层内的材料常数近似为常数。给出了任意厚度的四边简支横观各向同性功能梯度矩形板的热弹性分析,特别当板较薄时,与薄板理论进行了数值对比,发现两者结果吻合很好。最后研究了材料梯度指标对热弹性场的影响,结果显示梯度指标对热应力和位移都有着显著的作用:在不同的区间,梯度指标对它们有不同的影响;并且在同一区间,梯度指标对两者的影响程度也有所不同。 相似文献
98.
环形板与扇形板弯曲问题的级数解 总被引:1,自引:0,他引:1
由板的基本方程,将位移和荷载沿环向展开为傅里叶级数,可得用傅里叶级数及多项式表示的环形板和直边简支的扇形板的级数解.还用富里叶级数处理沿径向分段连续荷载的问题. 相似文献
99.
100.