全文获取类型
收费全文 | 36880篇 |
免费 | 504篇 |
国内免费 | 224篇 |
专业分类
化学 | 18275篇 |
晶体学 | 683篇 |
力学 | 1645篇 |
综合类 | 10篇 |
数学 | 3604篇 |
物理学 | 13391篇 |
出版年
2022年 | 315篇 |
2021年 | 355篇 |
2020年 | 334篇 |
2019年 | 329篇 |
2018年 | 523篇 |
2017年 | 455篇 |
2016年 | 722篇 |
2015年 | 424篇 |
2014年 | 724篇 |
2013年 | 1611篇 |
2012年 | 1512篇 |
2011年 | 1864篇 |
2010年 | 1359篇 |
2009年 | 1360篇 |
2008年 | 1549篇 |
2007年 | 1542篇 |
2006年 | 1407篇 |
2005年 | 1214篇 |
2004年 | 1147篇 |
2003年 | 1002篇 |
2002年 | 947篇 |
2001年 | 1358篇 |
2000年 | 977篇 |
1999年 | 824篇 |
1998年 | 619篇 |
1997年 | 591篇 |
1996年 | 519篇 |
1995年 | 486篇 |
1994年 | 452篇 |
1993年 | 395篇 |
1992年 | 477篇 |
1991年 | 476篇 |
1990年 | 462篇 |
1989年 | 429篇 |
1988年 | 445篇 |
1987年 | 429篇 |
1986年 | 374篇 |
1985年 | 442篇 |
1984年 | 471篇 |
1983年 | 343篇 |
1982年 | 387篇 |
1981年 | 375篇 |
1980年 | 319篇 |
1979年 | 400篇 |
1978年 | 378篇 |
1977年 | 394篇 |
1976年 | 391篇 |
1975年 | 342篇 |
1974年 | 322篇 |
1973年 | 339篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
We consider two classes of integrable nonlinear hyperbolic systems on Lie algebras. These systems generalize the principal chiral model. Each system is related to a pair of compatible Lie brackets and has a Lax representation, which is determined by the direct sum decomposition of the Lie algebra of Laurent series into the subalgebra of Taylor series and the complementary subalgebra corresponding to the pair. New examples of compatible Lie brackets are given. 相似文献
132.
Makarova N. A. Kazakova E. Kh. Salahutdinova Z. F. Enikeev K. M. Konovalov A. I. 《Russian Journal of General Chemistry》2002,72(10):1556-1559
Various-composition supramolecular complexes of calix[4]resorcinolarene with diglycidyl methylphosphonate were synthesized in organic solvents. The products have well-defined melting points, they are cleaved by acetylation, but remain unchanged on treatment with triethylamine. 相似文献
133.
Fabrication of bamboo-shaped GaN nanorods 总被引:1,自引:0,他引:1
H. Li J.Y. Li M. He X.L. Chen Z. Zhang 《Applied Physics A: Materials Science & Processing》2002,74(4):561-562
Bamboo-shaped GaN nanorods were formed through a simple sublimation method. They were characterized by means of X-ray powder
diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected-area
electron diffraction (SAED). The TEM image showed that the nanorods were bamboo-like. XRD, HRTEM and SAED patterns indicated
that the nanorods were single-crystal wurtzite GaN.
Received: 8 January 2001 / Accepted: 28 April 2001 / Published online: 20 December 2001 相似文献
134.
The aim of this paper is to highlight the added value of the generalized Gouy phase shift introduced by Siegman. Although suited for optical systems study, including those more complex than free space, we note that it did not meet the use that it deserves so far. The analysis of the whole of the ideas and analytical approaches associated to the important concept of the Gouy phase proves its effectiveness.
Usually, the resonance condition is systematically built on the basis of the equivalent empty cavity. Unfortunately, this approach does not cover some of the useful parameters of the real resonator. By means of the generalized Gouy phase and the self-consistent complex parameter q, we derive here a new approach for the calculation of the resonance condition for the real cavity. Moreover, the use of the generalized Gouy phase clearly simplifies the study of resonators, while making it possible to avoid the use of the Huygens’ Fresnel integral. 相似文献
135.
T. F. Sysoeva Z. A. Starikova M. V. Leont'eva N. M. Dyatlova 《Journal of Structural Chemistry》1991,31(5):814-817
All-Union Research Institute for Chemical Reagents and High-Purity Chemicals. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 5, pp. 140–143, September–October, 1990. 相似文献
136.
137.
Electronic structure calculations based on density functional theory were performed for solids and large molecules. The solids were represented by clusters of 60–100 atoms embedded in the potential of the external crystal. Magnetic moments and Mössbauer hyperfine parameters were derived. 相似文献
138.
I.G. Kalinina K.Z. Gumargalieva Yu.A. Shlyapnikov 《Polymer Degradation and Stability》1993,40(3):411-416
p-Toluensulfonic acid retards oxidation of polyethylene and, to a greater extent, of polyethylene-poly-p-methylstyrene blends. The real antioxidant is p-cresol, formed by p-toluensulfonic acid transformation in oxidizing polyethylene and, in blends, through peroxidation and subsequent acid-catalyzed decomposition of hydroperoxides of poly-p-methylstyrene. 相似文献
139.
140.
Z.-M. GET.-N. LIN 《Journal of sound and vibration》2002,251(3):519-542
The dynamic behavior of a gyrostat system subjected to external disturbance is studied in this paper. By applying numerical results, phase diagrams, power spectrum, period-T maps, and Lyapunov exponents are presented to observe periodic and choatic motions. The effect of the parameters changed in the system can be found in the bifurcation and parametric diagrams. For global analysis, the basins of attraction of each attractor of the system are located by employing the modified interpolated cell mapping (MICM) method. Several methods, the delayed feedback control, the addition of constant torque, the addition of periodic force, the addition of periodic impulse torque, injection of dither signal control, adaptive control algorithm (ACA) control and bang-bang control are used to control chaos effectively. Finally, synchronization of chaos in the gyrostat system is studied. 相似文献