全文获取类型
收费全文 | 405429篇 |
免费 | 3833篇 |
国内免费 | 1399篇 |
专业分类
化学 | 212537篇 |
晶体学 | 6345篇 |
力学 | 17703篇 |
综合类 | 7篇 |
数学 | 47197篇 |
物理学 | 126872篇 |
出版年
2021年 | 2953篇 |
2020年 | 3264篇 |
2019年 | 3755篇 |
2018年 | 4746篇 |
2017年 | 4631篇 |
2016年 | 7003篇 |
2015年 | 4496篇 |
2014年 | 6905篇 |
2013年 | 18612篇 |
2012年 | 13901篇 |
2011年 | 17018篇 |
2010年 | 11502篇 |
2009年 | 11316篇 |
2008年 | 15273篇 |
2007年 | 15501篇 |
2006年 | 14524篇 |
2005年 | 13217篇 |
2004年 | 12106篇 |
2003年 | 10719篇 |
2002年 | 10492篇 |
2001年 | 12056篇 |
2000年 | 9177篇 |
1999年 | 7193篇 |
1998年 | 5906篇 |
1997年 | 5986篇 |
1996年 | 5517篇 |
1995年 | 5146篇 |
1994年 | 4904篇 |
1993年 | 4852篇 |
1992年 | 5356篇 |
1991年 | 5390篇 |
1990年 | 5141篇 |
1989年 | 4978篇 |
1988年 | 5048篇 |
1987年 | 4948篇 |
1986年 | 4732篇 |
1985年 | 6283篇 |
1984年 | 6635篇 |
1983年 | 5477篇 |
1982年 | 5895篇 |
1981年 | 5773篇 |
1980年 | 5587篇 |
1979年 | 5657篇 |
1978年 | 5978篇 |
1977年 | 5801篇 |
1976年 | 6056篇 |
1975年 | 5510篇 |
1974年 | 5588篇 |
1973年 | 5928篇 |
1972年 | 3756篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
982.
V. M. Nagirnyi R. D. Apostolova E. M. Shembel’ 《Russian Journal of Applied Chemistry》2006,79(9):1443-1446
The surface morphology of V2O5, Co2O3, and MnO2 electroplated under different electrolysis conditions was studied. The nature of the electrocrystallization of these materials was suggested on the basis of the analysis results. 相似文献
983.
D Shaw 《The Journal of the Operational Research Society》2006,57(7):830-841
Problem-structuring group workshops can be used in organizations as a consulting tool and as a research tool. One example of the latter is using a problem-structuring method (PSM) to help a group tackle an organizational issue; meanwhile, researchers collect the participants’ initial views, discussion of divergent views, the negotiated agreement, and the reasoning for outcomes emerging. Technology can help by supporting participants in freely sharing their opinions and by logging data for post-workshop analyses. For example, computers let participants share views anonymously and without being influenced by others (as well as logging those views), and video-cameras can record discussions and intra-group dynamics. This paper evaluates whether technology-supported Journey Making workshops can be effective research tools that can capture quality research data when compared against theoretical performance benchmarks and other qualitative research tools. 相似文献
984.
985.
Sufficient conditions are presented for the stabilizability and global controllability of certain natural Lagrangian systems with a non-negative potential energy when there are ideal unilateral constraints. In the general case, the number of controls is less than the number of degrees of freedom and the controls are bounded by preassigned quantities. Examples of globally controlled systems with two degrees of freedom are considered in which the action of the unilateral constraints is modelled within the framework of classical collision theory. 相似文献
986.
Fe–Al alloys around the concentration of 30 at. % Al present re-entrant spin-glass behaviour at low temperatures. This behaviour is not completely understood and Mössbauer spectroscopy, combined with other experimental techniques, is useful to describe and explain this behaviour. Results show that the Mössbauer spectra coincide with the magnetic behaviour showed in literature and they can be explained as a magnetic cluster system whose magnetic clusters are getting smaller when the temperature is decreasing. When the temperature is reaching to the spin-glass transition at 92 K the spins in the paramagnetic matrix are moving slower and below this transition the spins are completely frozen. 相似文献
987.
988.
S. H. Faller R. W. Holloway S. C. Lee 《Journal of Radioanalytical and Nuclear Chemistry》1989,137(1):9-16
An investigation of cold fusion of deuterium was performed by electrolyzing heavy water in a cell containing a palladium cathode while monitoring levels of tritium and neutron-capture gamma rays. No activity was detected that would indicate a sustained fusion reaction had taken place. Activities that were observed can be attributed to electrolytic enrichment and a normal cosmic-ray induced background. 相似文献
989.
The solid solubility in the systems Y2O2S---La2O2S, Y2O2S---Gd2O2S, and Gd2O2S---La2O2S has been investigated. Solid solutions of all compounds, throughout the whole composition range, were readily obtained, using coprecipitated oxalates and a polysulfide flux. 相似文献
990.