全文获取类型
收费全文 | 4144篇 |
免费 | 324篇 |
国内免费 | 385篇 |
专业分类
化学 | 283篇 |
晶体学 | 1篇 |
力学 | 127篇 |
综合类 | 67篇 |
数学 | 1806篇 |
物理学 | 329篇 |
综合类 | 2240篇 |
出版年
2024年 | 6篇 |
2023年 | 39篇 |
2022年 | 63篇 |
2021年 | 66篇 |
2020年 | 87篇 |
2019年 | 96篇 |
2018年 | 92篇 |
2017年 | 118篇 |
2016年 | 108篇 |
2015年 | 106篇 |
2014年 | 171篇 |
2013年 | 232篇 |
2012年 | 212篇 |
2011年 | 250篇 |
2010年 | 215篇 |
2009年 | 245篇 |
2008年 | 211篇 |
2007年 | 297篇 |
2006年 | 268篇 |
2005年 | 237篇 |
2004年 | 223篇 |
2003年 | 175篇 |
2002年 | 169篇 |
2001年 | 151篇 |
2000年 | 153篇 |
1999年 | 138篇 |
1998年 | 101篇 |
1997年 | 115篇 |
1996年 | 68篇 |
1995年 | 62篇 |
1994年 | 65篇 |
1993年 | 52篇 |
1992年 | 53篇 |
1991年 | 49篇 |
1990年 | 19篇 |
1989年 | 30篇 |
1988年 | 28篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1971年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有4853条查询结果,搜索用时 0 毫秒
41.
The differential equations and the boundary conditions for the nonequilibrium binary distribution function of an unsymmetrical binary electrolyte are derived from the Ebeling-Falkenhagen continuity equation. The connection between the Onsager reciprocal relation and the binary distribution functions is shown. Further, Feistel's result for thec logc contribution to the conductance is extended to unsymmetrical binary electrolytes. The reason for the difference between Feistel's and Chen'sc logc term is explained, and the significance of Onsager's reciprocal relation for the calculation ofc logc and higher-concentration contributions of the conductance is discussed. 相似文献
42.
Global Existence of Solutions and Lower Bound Estimate of Blow-Up Time for the Keller-Segel Chemotaxis Model北大核心CSCD 下载免费PDF全文
A macroscopic nonlinear Keller-Segel model for chemotactic cell migration was considered, where the existence region of the model is a bounded convex one on Ω ⊂ RN(N≥2). The global existence of the solution on Ω ⊂ R3 was obtained by means of the energy estimate method. The lower bound of the blow-up time was proved for N = 3 and N = 2. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved. 相似文献
43.
The minimum time problem associated with a nonlinear control system is considered, and the unicity of the lower semicontinuous solution of the corresponding Bellman equation is investigated. A main tool in our approach is the Kruzkov transformation that enables us to work on
n
–{0}, where {0} is the target set, instead of the unknown reachable set.This research was carried out while the first author was visiting the Department of Mathematics, University of Genova, Genova, Italy. 相似文献
44.
LetW be a Wiener process of dimensiond3, starting from 0, and letX(t) be the total time spent byW in the ball centered at 0 with radiust. We give an affirmative answer to a conjecture of Taylor and Tricot(16) on the tail distribution ofX(t). Lévy's lower functions ofX(t) are characterized by an integral test. 相似文献
45.
本文讨论了正蕴涵BCK-代数的剩余刻划;证明了具有条件(S)的正蕴涵BCK-代数的伴随半群是一个下半格。 相似文献
46.
程曹宗 《首都师范大学学报(自然科学版)》1993,(1)
本文证明了关于Von Neumann型极大极小原理的许多结果,可作为论文“不动点型极大极小定理的一点推广”的直接结论。 相似文献
47.
48.
Orlik S. N. Ostapyuk V. A. Alekseenko L. M. 《Theoretical and Experimental Chemistry》2002,38(3):195-198
The possibility of making products of partial oxidation, alcohols and acids in particular, by the reaction of C3-C4 alkanes with nitrogen monoxide over oxide and zeolite catalysts is demonstrated. The most effective catalysts are CeO2 and Fe-TsVK. The dependence of the rate and selectivity of the process on the reaction conditions has been established. 相似文献
49.
M.G. Marmorino 《Journal of mathematical chemistry》2002,31(2):205-210
The asymptotic behavior of a system's ground-state energy from the t expansion of Horn and Weinstein has been suggested to have the form E
1(t)=E
1+exp(–a
n
t+b
n
). In the limit of very large t, this becomes E
1(t)=E
1+exp(–a
1
t+b
1). A simple analysis shows that the parameters are a
1=E
2–E
1 and b
1=ln[(E
2–E
1)|c
2|2/|c
1|2]. Functions are introduced which allow determination of a
1, b
1 and lower bounds to E
1. 相似文献
50.
C. Le Van 《Journal of Optimization Theory and Applications》1980,30(1):33-44
We define the degree of a family of convex functionsf
x, wherex
, and prove that, if this degree is different from zero, one has at least one Nash equilibrium point in . This is a criterion of localization of such equilibrium points. 相似文献