全文获取类型
收费全文 | 5523篇 |
免费 | 540篇 |
国内免费 | 528篇 |
专业分类
化学 | 1136篇 |
晶体学 | 12篇 |
力学 | 419篇 |
综合类 | 191篇 |
数学 | 3130篇 |
物理学 | 1703篇 |
出版年
2024年 | 6篇 |
2023年 | 47篇 |
2022年 | 88篇 |
2021年 | 152篇 |
2020年 | 109篇 |
2019年 | 146篇 |
2018年 | 131篇 |
2017年 | 192篇 |
2016年 | 241篇 |
2015年 | 176篇 |
2014年 | 336篇 |
2013年 | 393篇 |
2012年 | 312篇 |
2011年 | 350篇 |
2010年 | 252篇 |
2009年 | 370篇 |
2008年 | 376篇 |
2007年 | 378篇 |
2006年 | 358篇 |
2005年 | 284篇 |
2004年 | 249篇 |
2003年 | 227篇 |
2002年 | 219篇 |
2001年 | 187篇 |
2000年 | 178篇 |
1999年 | 127篇 |
1998年 | 138篇 |
1997年 | 100篇 |
1996年 | 89篇 |
1995年 | 51篇 |
1994年 | 66篇 |
1993年 | 31篇 |
1992年 | 37篇 |
1991年 | 27篇 |
1990年 | 15篇 |
1989年 | 28篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 3篇 |
排序方式: 共有6591条查询结果,搜索用时 500 毫秒
61.
We establish solvability of the boundary-value problems describing stationary and periodic flows of viscoplastic media. In the case of stationary flows we study the question of convergence of the Galerkin method. For the problem of periodic flows we prove a version of the second Bogolyubov theorem. 相似文献
62.
In this paper, we use an algebraic type of closure, which is called vector closure, and through it we introduce some adaptations to the proper efficiency in the sense of Hurwicz, Benson, and Borwein in real linear spaces without any particular topology. Scalarization, multiplier rules, and saddle-point theorems are obtained in order to characterize the proper efficiency in vector optimization with and without constraints. The usual convexlikeness concepts used in such theorems are weakened through the vector closure. 相似文献
63.
64.
65.
Pierre Gaspard 《Journal of statistical physics》2004,117(3-4):599-615
A concept of time-reversed entropy per unit time is introduced in analogy with the entropy per unit time by Shannon, Kolmogorov, and Sinai. This time-reversed entropy per unit time characterizes the dynamical randomness of a stochastic process backward in time, while the standard entropy per unit time characterizes the dynamical randomness forward in time. The difference between the time-reversed and standard entropies per unit time is shown to give the entropy production of Markovian processes in nonequilibrium steady states. 相似文献
66.
Finite element analysis of fluid flow with moving free surface has been performed in 2‐D and 3‐D. The new VOF‐based numerical algorithm that has been proposed by the present authors (Int. J. Numer. Meth. Fluids, submitted) was applied to several 2‐D and 3‐D free surface flow problems. The proposed free surface tracking scheme is based on two numerical tools; the orientation vector to represent the free surface orientation in each cell and the baby‐cell to determine the fluid volume flux at each cell boundary. The proposed numerical algorithm has been applied to 2‐D and 3‐D cavity filling and sloshing problems in order to demonstrate the versatility and effectiveness of the scheme. The proposed numerical algorithm resolved successfully the free surfaces interacting with each other. The simulated results demonstrated applicability of the proposed numerical algorithm to the practical problems of large free surface motion. It has been also demonstrated that the proposed free surface tracking scheme can be easily implemented in any irregular non‐uniform grid systems and can be extended to 3‐D free surface flow problems without additional efforts. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
67.
研究了在均匀分层介质中构成标准矢量波函数的必要条件。研究结果表明在均匀分层介质中构成标准矢量波函数一般需遵循Morse-Feshbach判据外,领示矢量只能选取与折射率变化方向一致的那根坐标轴单位矢量。但在某些特定的条件下,对领示矢量的选取条件可以放宽为只需遵循Morse-Feshbach判据即可。 相似文献
68.
作为H.F.Trotter[3]中一个结果的模拟,本文给出实二次函数域K中基本单位ε的范为N(ε)=g的一些充分必要条件,其中g为K的常数域Fq的非零乘法群Fq^*的生成元(2├q)。利用图论的语言,本文还给出了N(ε)=g的一些充分条件,这些条件对于数域也同样地适用,从而推广了Trotter[3]和前人工作中关于充分条件的结果。 相似文献
69.
Chen Yongnian 《模糊系统与数学》1995,(1)
ANTIFUZZYVECTORSPACES(Ⅱ)ChenYongnian(DepartmentofMathematics,XinjiangNormalUniversity,830054,Xinjiang,P.R.China)ANTIFUZZYVECT... 相似文献
70.
JINJIANG YUAN 《运筹学学报》1998,(3)
1.IntroductionGraphsconsideredinthispaperarefiniteandsimple.FOragraphG,V(G)andE(G)denoteitssetofvenicesandedges,respectively.AbijectionwillbecalledalabellingofG.Letpbeapositiverealnumber.ForagivenlabellingTofagraphG,definethegndiscrepencya.(G,ac)ofTasTheobjectiveoftheminimum-p--sumproblemistofindalabelling7ofagraphGsuchthatac(G,T)isassmallaspossible.ThelabellingTminimizinga.(G,7)iscalledanoptimalHsumlabellingofG.Theminimumvalueiscalledtheminimum-psumofG.ItisshowninI31thattheminimum-… 相似文献