全文获取类型
收费全文 | 1215篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
化学 | 741篇 |
晶体学 | 8篇 |
力学 | 20篇 |
数学 | 105篇 |
物理学 | 366篇 |
出版年
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 53篇 |
2012年 | 42篇 |
2011年 | 61篇 |
2010年 | 40篇 |
2009年 | 23篇 |
2008年 | 47篇 |
2007年 | 49篇 |
2006年 | 50篇 |
2005年 | 47篇 |
2004年 | 68篇 |
2003年 | 39篇 |
2002年 | 42篇 |
2001年 | 39篇 |
2000年 | 45篇 |
1999年 | 25篇 |
1998年 | 22篇 |
1997年 | 10篇 |
1996年 | 17篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 37篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 22篇 |
1975年 | 15篇 |
1974年 | 10篇 |
1973年 | 10篇 |
1972年 | 8篇 |
1971年 | 10篇 |
1935年 | 6篇 |
排序方式: 共有1240条查询结果,搜索用时 0 毫秒
91.
Hughes S 《Optics letters》2004,29(22):2659-2661
A theoretical formalism is presented to investigate enhanced radiative decay of excited dipoles in photonic crystal waveguides and nanocavities with a view to achieving efficient single-photon emission from embedded quantum dots. Surprisingly, large enhancement effects are achievable in both waveguides and nanocavities, and enhanced emission in the waveguide is shown to scale proportionally (inversely) with the photon group index (velocity). Further, a way to include radiative coupling of the quantum dot is shown, and the importance of its inclusion is subsequently demonstrated. 相似文献
92.
A semiclassical analysis of a two-dimensional electron droplet in a high, nonuniform magnetic field predicts that the droplet will form "fingered" patterns upon increasing the number of electrons. We construct explicit examples of these patterns using methods first developed for the flow of two-dimensional viscous fluids. We complement our analytical results with Monte Carlo simulations of the droplet wave function, and find that at the point where the semiclassical analysis predicts a cusp on the interface, the droplet fissions-a type of "quantum breakup" phenomenon. 相似文献
93.
94.
Ivchenko N Hughes CE Levitt MH 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,164(2):286-293
Cogwheel phase-cycling schemes are applied to sideband suppression and sideband separation experiments in solid-state NMR. It is shown that cogwheel phase cycles lead to the elimination of most pulse imperfection effects, while using far fewer experimental signal acquisitions than conventional phase-cycling methods. 相似文献
95.
G.?JundtEmail author G.?T.?Purves C.?S.?Adams I.?G.?Hughes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,27(3):273-276
We explore pump-probe non-linear Sagnac interferometry as a tool to measure the dispersive properties of a medium. We introduce the background theory, and show experimental spectra obtained on the D2 transition with 85Rb and 87Rb. The measured dispersion spectra are in excellent agreement with the Kramers-Kronig relations. In addition, as both beams traverse identical optical paths, Sagnac interferometry is very robust against mechanical vibrationReceived: 5 June 2003, Published online: 16 September 2003PACS:
39.30. + w Spectroscopic techniques - 33.55.Ad Optical activity, optical rotation; circular dichroismG. Jundt: Present address: Institute of Quantum Electronics, Department of Physics, ETH Zürich, Hönggerberg 8093, Switzerland. 相似文献
96.
Nanostructured copper was produced by deformation under large sliding loads. In the near surface layers, 10 nm scale microstructures form and coarsen with increasing depth from the surface. The graded structure enables characterization of the structural scale over several orders of magnitude. Analysis reveals that universal scaling of the microstructure exists from 10,000 to 10 nm. The limit of scale is pushed to an order of magnitude of the ultimate scale at which the crystallinity is lost. This universality opens the door for easy manufacture of ever finer scale components by deformation. 相似文献
97.
Hughes MS Klibanov AL Marsh JN Miller JG Brandenburger GH 《The Journal of the Acoustical Society of America》2000,108(2):813-820
We describe a technique for broadband measurements of the attenuation coefficient and phase velocity of highly attenuating liquid suspensions. To validate the technique we apply it to the ultrasound contrast agent Albunex at concentrations ranging from 0.69 x 10(6) particles/mL to 364 x 10(6) particles/mL. These longitudinal wave measurements were performed on Albunex suspensions maintained at 37 degrees C in a special time-domain reflectometer designed and constructed in our laboratory. The frequency-dependent attenuation coefficients and phase velocities obtained in the reflectometer are compared to broadband through-transmission measurements of these same quantities, which were also performed in our laboratory. Although comparison data between the two techniques are only available at lower concentrations, the agreement is quite good and serves to validate the methods described in this paper. 相似文献
98.
99.
Xu W Dutta D Xiong F Anderson B Auberbach L Averett T Bertozzi W Black T Calarco J Cardman L Cates GD Chai ZW Chen JP Choi S Chudakov E Churchwell S Corrado GS Crawford C Dale D Deur A Djawotho P Filippone BW Finn JM Gao H Gilman R Glamazdin AV Glashausser C Glöckle W Golak J Gomez J Gorbenko VG Hansen JO Hersman FW Higinbotham DW Holmes R Howell CR Hughes E Humensky B Incerti S de Jager CW Jensen JS Jiang X Jones CE Jones M Kahl R Kamada H Kievsky A Kominis I Korsch W Kramer K Kumbartzki G 《Physical review letters》2000,85(14):2900-2904
We have measured the transverse asymmetry A(T') in 3He(e,e(')) quasielastic scattering in Hall A at Jefferson Laboratory with high precision for Q2 values from 0.1 to 0.6 (GeV/c)(2). The neutron magnetic form factor G(n)(M) was extracted based on Faddeev calculations for Q2 = 0.1 and 0.2 (GeV/c)(2) with an experimental uncertainty of less than 2%. 相似文献
100.
Enzer DG Schauer MM Gomez JJ Gulley MS Holzscheiter MH Kwiat PG Lamoreaux SK Peterson CG Sandberg VD Tupa D White AG Hughes RJ James DF 《Physical review letters》2000,85(12):2466-2469
We report an experimental confirmation of the power-law relationship between the critical anisotropy parameter and ion number for the linear-to-zigzag phase transition in an ionic crystal. Our experiment uses laser cooled calcium ions confined in a linear radio-frequency trap. Measurements for up to ten ions are in good agreement with theoretical and numeric predictions. Implications on an upper limit to the size of data registers in ion trap quantum computers are discussed. 相似文献