全文获取类型
收费全文 | 3990篇 |
免费 | 312篇 |
国内免费 | 143篇 |
专业分类
化学 | 366篇 |
晶体学 | 23篇 |
力学 | 1973篇 |
综合类 | 36篇 |
数学 | 605篇 |
物理学 | 1442篇 |
出版年
2024年 | 3篇 |
2023年 | 24篇 |
2022年 | 50篇 |
2021年 | 43篇 |
2020年 | 84篇 |
2019年 | 63篇 |
2018年 | 75篇 |
2017年 | 100篇 |
2016年 | 138篇 |
2015年 | 103篇 |
2014年 | 220篇 |
2013年 | 200篇 |
2012年 | 193篇 |
2011年 | 270篇 |
2010年 | 161篇 |
2009年 | 224篇 |
2008年 | 235篇 |
2007年 | 282篇 |
2006年 | 233篇 |
2005年 | 198篇 |
2004年 | 166篇 |
2003年 | 157篇 |
2002年 | 146篇 |
2001年 | 102篇 |
2000年 | 102篇 |
1999年 | 92篇 |
1998年 | 112篇 |
1997年 | 93篇 |
1996年 | 74篇 |
1995年 | 72篇 |
1994年 | 72篇 |
1993年 | 57篇 |
1992年 | 58篇 |
1991年 | 55篇 |
1990年 | 56篇 |
1989年 | 22篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有4445条查询结果,搜索用时 595 毫秒
11.
等腰三角形Mindlin板的自由振动分析 总被引:2,自引:0,他引:2
提出了一种新方法来对基于 Mindlin剪切变形理论的等腰三角形板进行自由振动分析 .此方法采用了一种新的基函数并利用 pb-2 Rayleigh-Ritz边界函数得到了一种新型的 Ritz方法 .这种方法的有效性通过收敛性和对比性分析得到了证实 .数值结果表明此方法相当精确有效 . 相似文献
12.
S. Neukirch G.H.M. van der HeijdenJ.M.T. Thompson 《Journal of the mechanics and physics of solids》2002,50(6):1175-1191
We use three different approaches to describe the static spatial configurations of a twisted rod as well as its stability during rigid loading experiments. The first approach considers the rod as infinite in length and predicts an instability causing a jump to self-contact at a certain point of the experiment. Semi-finite corrections, taken into account as a second approach, reveal some possible experiments in which the configuration of a very long rod will be stable through out. Finally, in a third approach, we consider a rod of real finite length and we show that another type of instability may occur, leading to possible hysteresis behavior. As we go from infinite to finite length, we compare the different information given by the three approaches on the possible equilibrium configurations of the rod and their stability. These finite size effects studied here in a 1D elasticity problem could help us guess what are the stability features of other more complicated (2D elastic shells for example) problems for which only the infinite length approach is understood. 相似文献
13.
14.
关于非平行板电容器电容计算的讨论 总被引:4,自引:3,他引:1
用串联方法计算非平行板电容器的电容,简便地得到与其他方法相同的结果。 相似文献
15.
16.
A. D. Krisch 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):417-423
There will be a review of the history of polarized proton beams, and a discussion of the unexpected and still unexplained
large transverse spin effects found in several high-energy proton-proton spin experiments at the ZGS, AGS and Fermilab. Next,
there will be a discussion of present and possible future experiments on the violent elastic collisions of polarized protons
at IHEP-Protvino's 70GeV U-70 accelerator in Russia and the new high-intensity 50GeV J-PARC facility being built at Tokai
in Japan. 相似文献
17.
T. I. Khabakhpasheva 《Fluid Dynamics》2003,38(4):592-600
The problem of surface wave diffraction on a floating elastic plate is considered. The relation between the parameters of the elastic vibrations of the plate and the transmitted and reflected wave amplitudes is investigated. It is shown that the maximum amplitudes of the plate stresses and deflections depend nonmonotonically on the incident wave frequency and are reached simultaneously with the maxima of both the transmission coefficient and the length of the wave penetrating into the plate. This makes it possible to use the transmission coefficient as a parameter for investigating the maximum and minimum amplitudes of the hydroelastic vibrations of the plate. As an example, this criterion is used to minimize the vibrations of a plate whose leading edge is elastically connected to the bottom. 相似文献
18.
Electronic speckle interferometry (ESPI) is used to determine the Young's modulus E and Poisson ratio ν of an isotropic material. Micron scale deformations of the surface of the block of polymethyl-methacrylate (PMMA) are induced by normal application of a known near-point force. These deformations are recorded in speckle interferometric fringe patterns. An iterative minimum error inversion technique is developed to obtain the elastic properties from the positions of fringe peaks and troughs observed in the fringe patterns. Sensitivity tests of the method on calculated fringe patterns using measured experimental uncertainties suggest the technique will provide measures of the elastic moduli to better than 5%. In an experimental test on a bloc of PMMA (acrylic) the technique gave values of E and ν that differed from corresponding measures obtained using more conventional strain-gauge methods by less than 4%. 相似文献
19.
20.
The occurrence of charge on recoil56Mn produced by the (n,γ) reaction in polycrystalline potassium permanganate has been examined using the ‘charge plate technique’.
From considerations of capture gamma ray decay schemes and internal conversion it appears that, in a condensed medium, the
recoil atom develops charge after losing much of its initial kinetic energy which allows collection on charged electrodes.
Preliminary findings were presented at the International Symposium on Radiochemistry and Radiation Chemistry, RC-41 BARC,
Bombay, Feb. 4–6 (1991). 相似文献