全文获取类型
收费全文 | 261821篇 |
免费 | 1217篇 |
国内免费 | 638篇 |
专业分类
化学 | 116545篇 |
晶体学 | 3485篇 |
力学 | 16247篇 |
综合类 | 7篇 |
数学 | 53486篇 |
物理学 | 73906篇 |
出版年
2019年 | 2347篇 |
2018年 | 13788篇 |
2017年 | 13708篇 |
2016年 | 10262篇 |
2015年 | 2730篇 |
2014年 | 4005篇 |
2013年 | 7514篇 |
2012年 | 9379篇 |
2011年 | 17055篇 |
2010年 | 11196篇 |
2009年 | 11724篇 |
2008年 | 12980篇 |
2007年 | 15038篇 |
2006年 | 5930篇 |
2005年 | 6323篇 |
2004年 | 6393篇 |
2003年 | 6391篇 |
2002年 | 5599篇 |
2001年 | 5309篇 |
2000年 | 4026篇 |
1999年 | 3004篇 |
1998年 | 2851篇 |
1997年 | 2672篇 |
1996年 | 2507篇 |
1995年 | 2245篇 |
1994年 | 2154篇 |
1993年 | 2205篇 |
1992年 | 2203篇 |
1991年 | 2538篇 |
1990年 | 2448篇 |
1989年 | 2520篇 |
1988年 | 2397篇 |
1987年 | 2448篇 |
1986年 | 2300篇 |
1985年 | 2802篇 |
1984年 | 2795篇 |
1983年 | 2450篇 |
1982年 | 2505篇 |
1981年 | 2394篇 |
1980年 | 2210篇 |
1979年 | 2552篇 |
1978年 | 2713篇 |
1977年 | 2821篇 |
1976年 | 2933篇 |
1975年 | 2670篇 |
1974年 | 2596篇 |
1973年 | 2787篇 |
1972年 | 2295篇 |
1971年 | 2079篇 |
1970年 | 1946篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
992.
993.
994.
We prove new theorems on the justification of the averaging method for multifrequency oscillation systems with pulse influence at fixed times. 相似文献
995.
We consider the inverse problem of finding the unknown time-dependent leading coefficient and the free term in a parabolic equation. Boundary conditions and overdetermination conditions are local. We find conditions for the uniqueness and local existence. 相似文献
996.
Massoud Pourmahdian 《Archive for Mathematical Logic》2003,42(5):415-421
We prove that for any simple theory which is constructed via Fr?issé-Hrushovski method, if the forking independence is the
same as the d-independence then the stable forking property holds.
Received: 22 January 2001 /
Published online: 19 December 2002
This article is part of the author's D-Phil thesis, written at the University of Oxford and supported by the Ministry of
Higher Education of Iran. The author would like to thank the Institute for Studies in Theoretical Physics and Mathematics
(IPM), Tehran, Iran, for its financial support whilst working on this article.
Mathematics Subject Classification (2000): 03C45
Key words or phrases: Generic structures – Fr?issé-Hrushovski method – Predimension – Simple theories – Stable theories – Stable forking conjecture 相似文献
997.
R. M. Sardarly O. A. Samedov I. Sh. Sadykhov V. A. Aliev 《Physics of the Solid State》2003,45(6):1118-1121
The relaxor properties of Fe-doped TlInS2 crystals are investigated. It is shown that Fe-doped TlInS2 compounds exhibit all features inherent in relaxor ferroelectric materials. The temperature range of existence of the microdomain (relaxor) state and the temperature of the transition from this state to a macro-domain state are determined. 相似文献
998.
The classical economic order quantity (EOQ) model assumes that items produced are of perfect quality and that the unit cost of production is independent of demand. However, in realistic situations, product quality is never perfect, but is directly affected by the reliability of the production process. In this paper, we consider an EOQ model with imperfect production process and the unit production cost is directly related to process reliability and inversely related to the demand rate. In addition, a numerical example is given to illustrate the developed model. Sensitivity analysis is also performed and discussed. 相似文献
999.
1000.
Baidyshev V. S. Udodov V. N. Popov A. A. Potekaev A. I. 《Russian Physics Journal》2003,46(12):1193-1198
The paper offers a method for calculating phase diagrams of polytype transformations in close-packed crystals based on the generalized axial Ising's model of finite dimensions at non-zero temperatures. Using the Metropolis algorithm, the behavior of systems with polytype transitions is studied under the conditions of changing external shear stress and temperature. The longest polytype period considered here is taken to be 30 close-packed planes. 相似文献