首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   106489篇
  免费   4432篇
  国内免费   3206篇
化学   43969篇
晶体学   1045篇
力学   8495篇
综合类   273篇
数学   34938篇
物理学   25407篇
  2024年   105篇
  2023年   589篇
  2022年   912篇
  2021年   1014篇
  2020年   1112篇
  2019年   1083篇
  2018年   11099篇
  2017年   10862篇
  2016年   7206篇
  2015年   2090篇
  2014年   1816篇
  2013年   2349篇
  2012年   6311篇
  2011年   12939篇
  2010年   7190篇
  2009年   7569篇
  2008年   8257篇
  2007年   10280篇
  2006年   1711篇
  2005年   2515篇
  2004年   2445篇
  2003年   2733篇
  2002年   1731篇
  2001年   805篇
  2000年   850篇
  1999年   807篇
  1998年   771篇
  1997年   720篇
  1996年   855篇
  1995年   623篇
  1994年   542篇
  1993年   483篇
  1992年   427篇
  1991年   384篇
  1990年   306篇
  1989年   260篇
  1988年   216篇
  1987年   193篇
  1986年   184篇
  1985年   164篇
  1984年   130篇
  1983年   97篇
  1982年   82篇
  1981年   74篇
  1980年   64篇
  1979年   61篇
  1978年   53篇
  1975年   44篇
  1914年   45篇
  1909年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically.  相似文献   
7.
Current methodologies used for the inference of thin film stress through curvature measurement are strictly restricted to stress and curvature states that are assumed to remain uniform over the entire film/substrate system. These methodologies have recently been extended to a single layer of thin film deposited on a substrate subjected to the non-uniform misfit strain in the thin film. Such methodologies are further extended to multi-layer thin films deposited on a substrate in the present study. Each thin film may have its own non-uniform misfit strain. We derive relations between the stresses in each thin film and the change of system curvatures due to the deposition of each thin film. The interface shear stresses between the adjacent films and between the thin film and the substrate are also obtained from the system curvatures. This provides the basis for the experimental determination of thin film stresses in multi-layer thin films on a substrate.  相似文献   
8.
Structural hierarchy of rock masses and the mechanisms of its formation   总被引:1,自引:0,他引:1  
The formation mechanisms for the structural hierarchy in geological media are discussed. It is shown that the formation of such a hierarchy is caused by certain external and internal circumstances. The first ones consist in the fact that, because of external actions, the Earth’s poles continuously execute the translational and rotational motions responsible for a regular structure of rock fracture and for the appearance of the scale factor √2. The second ones consist in the fact that, under the action of many random factors and because of external actions, during the formation of geological media there appear dissipative structures and, hence, some self-similar fractal structures are formed.  相似文献   
9.
Nicholas Nathan tries to resist the current version of the causal argument for sense-data in two ways. First he suggests that, on what he considers to be the correct re-construction of the argument, it equivocates on the sense of proximate cause. Second he defends a form of disjunctivism, by claiming that there might be an extra mechanism involved in producing veridical hallucination, that is not present in perception. I argue that Nathan’s reconstruction of the argument is not the appropriate one, and that, properly interpreted, the argument does not equivocate on proximate cause. Furthermore, I claim that his postulation of a modified mechanism for hallucinations is implausibly ad hoc.  相似文献   
10.
A closed but approximate formula of Green’s function for an arbitrary aggregate of cubic crystallites is given to derive the e?ective elastic sti?ness tensor of the polycrystal. This formula, which includes three elastic constants of single cubic c…  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号