全文获取类型
收费全文 | 3330篇 |
免费 | 68篇 |
国内免费 | 13篇 |
专业分类
化学 | 2126篇 |
晶体学 | 13篇 |
力学 | 43篇 |
数学 | 467篇 |
物理学 | 762篇 |
出版年
2021年 | 31篇 |
2020年 | 57篇 |
2019年 | 44篇 |
2018年 | 24篇 |
2016年 | 55篇 |
2015年 | 62篇 |
2014年 | 68篇 |
2013年 | 115篇 |
2012年 | 115篇 |
2011年 | 151篇 |
2010年 | 97篇 |
2009年 | 92篇 |
2008年 | 125篇 |
2007年 | 131篇 |
2006年 | 115篇 |
2005年 | 96篇 |
2004年 | 111篇 |
2003年 | 96篇 |
2002年 | 94篇 |
2001年 | 64篇 |
2000年 | 52篇 |
1999年 | 42篇 |
1998年 | 35篇 |
1997年 | 58篇 |
1996年 | 53篇 |
1995年 | 45篇 |
1994年 | 46篇 |
1993年 | 45篇 |
1992年 | 43篇 |
1991年 | 35篇 |
1990年 | 40篇 |
1989年 | 50篇 |
1988年 | 38篇 |
1987年 | 45篇 |
1986年 | 46篇 |
1985年 | 64篇 |
1984年 | 48篇 |
1983年 | 32篇 |
1982年 | 46篇 |
1981年 | 43篇 |
1980年 | 33篇 |
1979年 | 46篇 |
1978年 | 49篇 |
1977年 | 56篇 |
1976年 | 49篇 |
1975年 | 34篇 |
1974年 | 36篇 |
1973年 | 35篇 |
1972年 | 28篇 |
1970年 | 23篇 |
排序方式: 共有3411条查询结果,搜索用时 15 毫秒
101.
Calum Williams Yunuen Montelongo Jaime Oscar Tenorio‐Pearl Andrea Cabrero‐Vilatela Stephan Hofmann William I. Milne Timothy D. Wilkinson 《固体物理学:研究快报》2015,9(2):125-129
Digital holography requires arrays of small reconfigurable elements to achieve complex reconstruction of the hologram with common systems based on pixels utilizing liquid crystal on silicon (LCoS) technology. The backplane of a typical pixel element is potentially underutilized and thus relatively large physical areas exist in which information can be stored and exploited to give additional functionality to pixel elements. Polarisation and wavelength dependent optical properties can be achieved in small areas using the plasmonic effects of optical antennae. The integration of LCs with optical antennae‐based plasmonic holograms allows active modulation of the far field pattern. The work here demonstrates the concept that conventional LCoS pixel elements can be greatly enhanced with the integration of plasmonic holograms, composed of optical antennae patterned on the surface, giving rise to new levels of modulation capability for holographic pixel elements. Using LCs, polarisation dependent effects in plasmonic holograms can be switched. ‘Engineered pixels', with sub‐wavelength multiplexing over both polarisation and wavelength, can increase the channel capacity of a typical LC display device. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
102.
S. Roth G. Angloher I. Bavykina A. Brown C. Ciemniak G. Deuter F.v. Feilitzsch D. Hauff M. Hofmann J. Imber C. Isaila M. Kiefer H. Kraus J.-C. Lanfranchi B. Majorovits M. Malek V. Mikhailik F. Petricca W. Potzel K. Rottler K. Schäffner S. Scholl M.v. Sivers R. Strauss I. Usherov 《Progress in Particle and Nuclear Physics》2010,64(2):457-459
The current status of the direct Dark Matter experiments CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) and the planned EURECA (European Underground Rare Event Calorimeter Array) is presented. Both experiments are aimed at the direct detection of WIMPs (Weakly Interacting Massive Particles), potential candidates for the Dark Matter in the universe. New design developments of the cryogenic detectors operated at mK temperatures are investigated to optimize detector performance and to simplify mass production. Thus, CRESST is also providing a basis for the EURECA project, aimed at a ton of cryogenic detectors with a multi-material target. 相似文献
103.
104.
F. P. He?berger S. Antalic B. Sulignano D. Ackermann S. Heinz S. Hofmann B. Kindler J. Khuyagbaatar I. Kojouharov P. Kuusiniemi M. Leino B. Lommel R. Mann K. Nishio A. G. Popeko ?. ?áro B. Streicher J. Uusitalo M. Venhart A. V. Yeremin 《The European Physical Journal A - Hadrons and Nuclei》2010,43(1):55-66
A detailed $ \gamma$ spectroscopic decay study of two K isomers in 254No was performed. In addition to the previously reported $ \gamma$ lines two new transitions of E = 778 , 856keV could be attributed to the decay pattern of 254m1No ( T 1/2 = 275±7 ms). The population of an excited band built up on this isomer ( $\ensuremath K^{\pi} =8^{-}$ by the decay of 254m2No ( T 1/2 = 198±13 μs) could be proven by measuring delayed $ \gamma$ - $ \gamma$ coincidences between transitions stemming from the decay of both isomeric states. The energies of the band members could be established up to $\ensuremath I^{\pi} = 15^{-}$ . A spontaneous fission branch of (2.0±1.2)×10-4 was measured for 254m1No , an upper limit of $ \le$ 1.2×10-4 was estimated for 254m2No . These values demonstrate the high stability of multi-quasiparticle configurations against spontaneous fission. Evidence for an $ \alpha$ decay branch of 254m1No in the order of 1×10-4 was found. 相似文献
105.
Phase resolved optical emission spectroscopy of coaxial microplasma jet operated with He and Ar 总被引:1,自引:0,他引:1
106.
Dimensional reduction of generalized gravity theories or string theories generically yields dilaton fields in the lower-dimensional effective theory. Thus at the level of D=4 theories and cosmology, many models contain more than just one scalar field (e.g., inflaton, Higgs, quintessence). Our present work is restricted to two-dimensional gravity theories with only two dilatons which nevertheless allow a large class of physical applications. The notions of factorizability, simplicity and conformal simplicity, Einstein form, and Jordan form are the basis of an adequate classification. We show that practically all physically motivated models belong either to the class of factorizable simple theories (e.g., dimensionally reduced gravity, bosonic string) or to factorizable conformally simple theories (e.g., spherically reduced scalar-tensor theories). For these theories a first order formulation is constructed straightforwardly. As a consequence an absolute conservation law can be established. 相似文献
107.
108.
109.
Gamma-gamma directional correlations have been investigated for the cascades of 135-30 keV and 135-32 keV in201Hg from the decay of201Tl. A combination of NaI (Tl) and Si (Li) detectors was used for the experiments. Spin values ofI=1/2, 3/2 and 1/2 have been assigned to 1.58, 32.19 and 167.49 keV energy levels. In addition, the relative intensities of theγ rays have been measured with a Ge (Li) detector system. The results are 2.2±0.2, 2.2±0.2, 26.5±1.3, 1.6±0.1 and 100 for theγ rays of 30.60, 32.19, 135.34, 165.88 and 167.43 keV energies, respectively. 相似文献
110.
The performance of a model-based tracking controller depends on the quality of the underlying model. Especially for flexible multibody systems, the derivation of a suitable model and the subsequent controller design are challenging tasks. In the paper, it is shown how in a straightforward approach a feed-forward controller for a flexible multibody system is designed based on a simplified model which approximates an elastic beam by a combination of rigid beams and force elements. Furthermore, the modelling error due to this harsh simplification is included as uncertainty in the simplified model and considered in the model-based feed-forward controller design using fuzzy arithmetic. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献