全文获取类型
收费全文 | 205718篇 |
免费 | 1765篇 |
国内免费 | 594篇 |
专业分类
化学 | 103392篇 |
晶体学 | 3345篇 |
力学 | 9314篇 |
综合类 | 5篇 |
数学 | 22693篇 |
物理学 | 69328篇 |
出版年
2021年 | 1706篇 |
2020年 | 1837篇 |
2019年 | 2041篇 |
2018年 | 2728篇 |
2017年 | 2632篇 |
2016年 | 3843篇 |
2015年 | 2355篇 |
2014年 | 3677篇 |
2013年 | 9153篇 |
2012年 | 7364篇 |
2011年 | 8878篇 |
2010年 | 6151篇 |
2009年 | 5974篇 |
2008年 | 8014篇 |
2007年 | 8212篇 |
2006年 | 7801篇 |
2005年 | 6959篇 |
2004年 | 6475篇 |
2003年 | 5688篇 |
2002年 | 5518篇 |
2001年 | 6434篇 |
2000年 | 4942篇 |
1999年 | 3810篇 |
1998年 | 3048篇 |
1997年 | 3051篇 |
1996年 | 2804篇 |
1995年 | 2631篇 |
1994年 | 2480篇 |
1993年 | 2346篇 |
1992年 | 2698篇 |
1991年 | 2676篇 |
1990年 | 2603篇 |
1989年 | 2403篇 |
1988年 | 2450篇 |
1987年 | 2451篇 |
1986年 | 2283篇 |
1985年 | 2963篇 |
1984年 | 3215篇 |
1983年 | 2634篇 |
1982年 | 2804篇 |
1981年 | 2776篇 |
1980年 | 2642篇 |
1979年 | 2733篇 |
1978年 | 2824篇 |
1977年 | 2822篇 |
1976年 | 2891篇 |
1975年 | 2673篇 |
1974年 | 2644篇 |
1973年 | 2778篇 |
1972年 | 1763篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
We present results for the determination of the equilibrium microstate probability distribution of a class of strongly interacting systems obeying stochastic dynamics but without the necessity of detailed balance. The specific case of Ising systems is highlighted, with applications to non-symmetric synaptic neural networks and more general recurrent Boolean networks. 相似文献
93.
Stationary solitons are found to occur in two-dimensional media with a variable saturation magnetization whose square is a
harmonic function of the coordinates. It is shown in this case that the Landau-Lifshits equation can be reduced to the integrable
O(3) sigma-model in curved space. Some properties of the solutions obtained are discussed. Bibliography: 15 titles.
Translated by V. D. Lipovskii. 相似文献
94.
D. J. Hartfiel 《Linear and Multilinear Algebra》1994,36(4):293-304
In this paper we consider the nonnegative matrix system ciA+uiB=ci+1 where the nonnegative matrix A is allowed to vary, within bounds. The cone control problem is to find a nonnegative matrix B such that if Ci is a nonnegative vector in a specified cone, then there is a nonnegative vector ui such that ci+1 is in that cone. We extend this problem to input control by finding a B such that the cone, generated by the rows of B, is as small as possible. Thus, the percent distribution of ∣uiB∣ through the states of the sustem by uiB is either constant or varies little. 相似文献
95.
96.
V. D. Levchenko A. I. Morozov A. S. Sigov 《Journal of Experimental and Theoretical Physics》2002,94(5):985-991
Multilayer ferromagnet-layered antiferromagnet (Fe/Cr) structures frustrated because of roughness of interlayer boundaries were studied by mathematical modeling methods. The phase diagram of a three-layer system (plotted as film thickness versus the degree of roughness of the interfaces) was obtained, and the order parameter distributions in each phase were determined. The character of phase transitions in this system was studied. The applicability range of the Slonczewski magnetic proximity model was determined. 相似文献
97.
Fluorescence line narrowing (FLN) spectroscopy was used to study the role of the polypeptide chain in influencing the spectrum of Zn-substituted cytochrome c (Zn cyt c) and metal-free cyt c (porphyrin cyt c). For both derivatives the spectra show characteristics of relaxed fluorescence from an inhomogeneously broadened sample. Zero phonon lines and phonon wings can be clearly distinguished, and vibrational frequencies of the ground and excited states were identified. The inhomogeneous distribution width for porphyrin cyt c is slightly wider than that of Zn cyt c and a second population of molecules was apparent in the porphyrin cyt c. The phonon coupling was greater for Zn cyt c than for porphyrin cyt c, which may be due to the extra coupling to the polypeptide chain by metal ligation.This work has been done in partial fulfillment of the requirements for the Doctor of Philosophy degree. 相似文献
98.
99.
G. Baldsiefen H. Hübel W. Korten U. J. van Severen J. A. Cizewski N. H. Medina D. R. Napoli C. Rossi Alvarez G. Lo Bianco S. Signorelli 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):337-338
High-spin states in196Pb have been populated using the reaction170Er(30Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin. 相似文献
100.
A Monte-Carlo model is described which has been developed for calculation of multiply scattered LIDAR returns. Results are shown for the common problem selected by the MUSCLE (MUltiple SCattering LIDAR Experiments) group for intercomparison, which represents a typical ground-based cloud-sensing scenario. This is contrasted with returns from the same cloud sensed by a space-based LIDAR, where multiple-scattering effects are much greater. The magnitude of multiple-scattering effects is seen to be largely determined by the optical depth across the receiver field of view at the cloud. 相似文献