全文获取类型
收费全文 | 30005篇 |
免费 | 5263篇 |
国内免费 | 3655篇 |
专业分类
化学 | 22129篇 |
晶体学 | 388篇 |
力学 | 1732篇 |
综合类 | 203篇 |
数学 | 3115篇 |
物理学 | 11356篇 |
出版年
2024年 | 59篇 |
2023年 | 622篇 |
2022年 | 772篇 |
2021年 | 1062篇 |
2020年 | 1317篇 |
2019年 | 1334篇 |
2018年 | 1167篇 |
2017年 | 1082篇 |
2016年 | 1501篇 |
2015年 | 1569篇 |
2014年 | 1865篇 |
2013年 | 2341篇 |
2012年 | 2818篇 |
2011年 | 2871篇 |
2010年 | 2006篇 |
2009年 | 1937篇 |
2008年 | 2127篇 |
2007年 | 1865篇 |
2006年 | 1687篇 |
2005年 | 1424篇 |
2004年 | 1073篇 |
2003年 | 845篇 |
2002年 | 780篇 |
2001年 | 616篇 |
2000年 | 547篇 |
1999年 | 503篇 |
1998年 | 415篇 |
1997年 | 382篇 |
1996年 | 324篇 |
1995年 | 295篇 |
1994年 | 294篇 |
1993年 | 238篇 |
1992年 | 222篇 |
1991年 | 180篇 |
1990年 | 149篇 |
1989年 | 126篇 |
1988年 | 86篇 |
1987年 | 65篇 |
1986年 | 64篇 |
1985年 | 59篇 |
1984年 | 36篇 |
1983年 | 31篇 |
1982年 | 21篇 |
1981年 | 16篇 |
1980年 | 22篇 |
1979年 | 13篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1974年 | 11篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
101.
L. E. Payne P. W. Schaefer J. C. Song 《Mathematical Methods in the Applied Sciences》2004,27(17):2045-2053
Energy bounds are derived for Dirichlet type boundary value problems for the Navier–Stokes and Stokes equations when a combination of the solution values initially and at a later time is prescribed. The bounds are obtained by means of a differential inequality and imply uniqueness and continuous data dependence of the solutions for a range of values of the parameter in the non‐standard auxiliary condition. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
102.
In this paper, we consider Girsanov transforms of pure jump type for discontinuous Markov processes. We show that, under some quite natural conditions, the Green functions of the Girsanov transformed process are comparable to those of the original process. As an application of the general results, the drift transform of symmetric stable processes is studied in detail. In particular, we show that the relativistic α-stable process in a bounded C1,1-smooth open set D can be obtained from symmetric α-stable process in D through a combination of a pure jump Girsanov transform and a Feynman-Kac transform. From this, we deduce that the Green functions for these two processes in D are comparable. 相似文献
103.
S. P. Savin L. M. Zelenyi E. Amata J. Buechner J. Blecki S. I. Klimov B. Nikutowski J. L. Rauch S. A. Romanov A. A. Skalsky V. N. Smirnov P. Song K. Stasiewicz 《JETP Letters》2004,79(8):368-371
The study of the interaction between collisionless plasma flow and stagnant plasma revealed the presence of an outer boundary layer at the border of a geomagnetic trap, where the super-Alfvén subsonic laminar flow changes over to the dynamic regime characterized by the formation of accelerated magnetosonic jets and decelerated Alfvén flows with characteristic relaxation times of 10–20 min. The nonlinear interaction of fluctuations in the initial flow with the waves reflected from an obstacle explains the observed flow chaotization. The Cherenkov resonance of the magnetosonic jet with the fluctuation beats between the boundary layer and the incoming flow is the possible mechanism of its formation. In the flow reference system, the incoming particles are accelerated by the electric fields at the border of boundary layer that arise self-consistently as a result of the preceding wave-particle interactions; the inertial drift of the incoming ions in a transverse electric field increasing toward the border explains quantitatively the observed ion acceleration. The magnetosonic jets may carry away downstream up to a half of the unperturbed flow momentum, and their dynamic pressure is an order of magnitude higher than the magnetic pressure at the obstacle border. The appearance of nonequilibrium jets and the boundary-layer fluctuations are synchronized by the magnetosonic oscillations of the incoming flow at frequencies of 1–2 mHz. 相似文献
104.
105.
Song Jiang 《Mathematische Nachrichten》1998,190(1):169-183
We consider initial boundary value problems for the equations of the one-dimensional motion of a viscous, heat-conducting gas with density-dependent viscosity that decreases (to zero) with decreasing density. We prove that if the viscosity does not decrease to zero too rapidly, then smooth solutions exist globally in time. 相似文献
106.
107.
108.
以金刚石压腔高压装置为工具,用Ⅱ型金刚石作压砧兼红外窗口,对本征态聚苯胺进行了高压(0~8.4 GPa)就位红外光谱测试。结果表明:在4.8~5.2 GPa压力区间,代表醌环振动的吸收峰相对代表苯环振动的吸收峰变小,表明聚苯胺在此压力区间结构上发生了显著变化,且这种变化是不可逆的。聚苯胺的高压(0~14.5 GPa)电阻测量结果表明:当压力小于7.5 GPa时,电阻随压力升高而显著降低,据此认为聚苯胺为电子性导电物质;在7.5 GPa处电阻出现极小值,然后又缓慢升高,至10 GPa后基本不变。推测聚苯胺电阻极小值是由结构变化引起的。至于红外光谱与电阻测量结果反映聚苯胺结构变化的压力值不一致,可能是由于测试条件不同所致。 相似文献
109.
110.