全文获取类型
收费全文 | 13313篇 |
免费 | 1002篇 |
国内免费 | 449篇 |
专业分类
化学 | 6276篇 |
晶体学 | 268篇 |
力学 | 1003篇 |
综合类 | 56篇 |
数学 | 1492篇 |
物理学 | 5669篇 |
出版年
2024年 | 18篇 |
2023年 | 131篇 |
2022年 | 277篇 |
2021年 | 284篇 |
2020年 | 290篇 |
2019年 | 293篇 |
2018年 | 312篇 |
2017年 | 238篇 |
2016年 | 388篇 |
2015年 | 352篇 |
2014年 | 504篇 |
2013年 | 754篇 |
2012年 | 951篇 |
2011年 | 1019篇 |
2010年 | 804篇 |
2009年 | 731篇 |
2008年 | 789篇 |
2007年 | 722篇 |
2006年 | 702篇 |
2005年 | 525篇 |
2004年 | 454篇 |
2003年 | 392篇 |
2002年 | 332篇 |
2001年 | 537篇 |
2000年 | 440篇 |
1999年 | 353篇 |
1998年 | 254篇 |
1997年 | 245篇 |
1996年 | 231篇 |
1995年 | 191篇 |
1994年 | 165篇 |
1993年 | 127篇 |
1992年 | 119篇 |
1991年 | 125篇 |
1990年 | 105篇 |
1989年 | 79篇 |
1988年 | 58篇 |
1987年 | 41篇 |
1986年 | 45篇 |
1985年 | 47篇 |
1984年 | 36篇 |
1983年 | 22篇 |
1982年 | 33篇 |
1981年 | 34篇 |
1980年 | 25篇 |
1979年 | 20篇 |
1978年 | 25篇 |
1977年 | 19篇 |
1976年 | 18篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
K.?L.?YaoEmail author Q.?M.?Liu Z.?L.?Liu X.?W.?Liu G.?Y.?Sun 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,35(3):365-370
We introduce a solid-on-solid growth process which evolves by random deposition of dimers, surface diffusion, and evaporation
of monomers from the edges of plateaus. It is shown that the model exhibits a robust transition from a smooth to a rough phase.
The roughening transition is driven by an absorbing phase transition at the bottom layer of the interface, which displays
the same type of critical behavior as the pair contact process with diffusion 2A↦3A, 2A↦.
Received 14 October 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: Haye.Hinrichsen@physik.uni-wuppertal.de 相似文献
942.
In this paper, we consider the following forced higher-order nonlinear neutral difference equation
943.
D. P. Dryanov M. A. Qazi Q. I. Rahman 《Proceedings of the American Mathematical Society》2003,131(9):2741-2751
Extensions of two classical results about polynomials, one due to W. Markov and the other due to Duffin and Schaeffer, are obtained in this paper. An interesting result of S. Bernstein, which went unnoticed until it was rediscovered by P. Erdos, years later, is also generalized. Our results are especially amenable to numerical calculations, and may, therefore, be of some practical importance.
944.
We suggest a closed form expression for the path integral of quantum transition amplitudes. We introduce a quantum action with parameters different from the classical action. We present numerical results for the harmonic oscillator with weak perturbation, the quartic potential, and the double well potential. The quantum action is relevant for quantum chaos and quantum instantons. 相似文献
945.
Self-induced phase matching in stimulated four-wave mixing in a nonbirefringent single-mode optical fiber has been observed. It is shown that in a nonbirefringent single-mode fiber the phase matching that is necessary for stimulated four-wave mixing can be accomplished with a combination of self-phase modulation and cross-phase modulation induced by a pump-laser pulse. 相似文献
946.
We describe an optical processing method for characterizing tissue pathology that is based on principal-component analysis of light-induced autofluorescence. A set of optical spectral filters, which are related to the principal-component loading vectors, is designed to process the autofluorescence signal optically and to generate principal-component scores from the autofluorescence spectra. The scores are then correlated with the tissue pathology. An optical processing system is designed that uses the in vivo fluorescence spectra recorded from nasopharyngeal tissues. We demonstrate that the system can differentiate nasopharyngeal carcinoma from normal tissue with a high degree of sensitivity and specificity and that the optical filters used in the system can be manufactured. 相似文献
947.
Changhong Chen Xinjian Yi Jing Zhang Bifeng Xiong 《International Journal of Infrared and Millimeter Waves》2001,22(1):53-58
Mixed vanadium oxide thin films, as VO2 for the main composition are materials for uncooled microbolometer due to their high temperature coefficient of resistance (TCR) at room temperature. This paper describes the design and fabrication of 8-element linear array IR uncooled microbolometers using the films and micromachining technology. The characteristics of the array is investigated in the spectral region of 8–12 m. The fabricated detectors exhibit responsivity of up to 10 KV/W, typical detectivity of 1.89×108 cmHz1/2/W, and thermal time constant of 11 ms, at 296 K and at a frequency of 30 Hz. Furthermore, The uncorrected response uniformity of the linear array bolometers is less than 20%. 相似文献
948.
Pedro L. Q. Pergher 《Transactions of the American Mathematical Society》2001,353(1):175-189
Given a collection of real vector bundles over a closed manifold , suppose that, for some is of the form , where is the trivial one-dimensional bundle. In this paper we prove that if is the fixed data of a -action, then the same is true for the Whitney sum obtained from by replacing by . This stability property is well-known for involutions. Together with techniques previously developed, this result is used to describe, up to bordism, all possible -actions fixing the disjoint union of an even projective space and a point. 相似文献
949.
Baryon rapidity loss in relativistic Au + Au collisions 总被引:4,自引:0,他引:4
Back BB Betts RR Chang J Chang WC Chi CY Chu YY Cumming JB Dunlop JC Eldredge W Fung SY Ganz R Garcia E Gillitzer A Heintzelman G Henning WF Hofman DJ Holzman B Kang JH Kim EJ Kim SY Kwon Y McLeod D Mignerey AC Moulson M Nanal V Ogilvie CA Pak R Ruangma A Russ DE Seto RK Stanskas PJ Stephans GS Wang HQ Wolfs FL Wuosmaa AH Xiang H Xu GH Yao HB Zou CM 《Physical review letters》2001,86(10):1970-1973
An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that display a broad peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a stationary source at midrapidity decreases with increasing beam energy. The data suggest that the stopping is substantially less than complete at these energies. 相似文献
950.
Large coherence area thin-film photonic stop-band lasers 总被引:4,自引:0,他引:4
We demonstrate that the shift of the stop-band position with increasing oblique angle in periodic structures results in a wide transverse exponential field distribution corresponding to strong angular confinement of the radiation. The beam expansion follows an effective diffusive equation depending only upon the spectral mode width. In the presence of gain, the beam cross section is limited only by the size of the gain area. As an example of an active periodic photonic medium, we calculate and measure laser emission from a dye-doped cholesteric liquid crystal film. 相似文献