全文获取类型
收费全文 | 4301篇 |
免费 | 308篇 |
国内免费 | 160篇 |
专业分类
化学 | 932篇 |
晶体学 | 17篇 |
力学 | 489篇 |
综合类 | 46篇 |
数学 | 2685篇 |
物理学 | 600篇 |
出版年
2024年 | 7篇 |
2023年 | 57篇 |
2022年 | 41篇 |
2021年 | 73篇 |
2020年 | 105篇 |
2019年 | 121篇 |
2018年 | 113篇 |
2017年 | 115篇 |
2016年 | 129篇 |
2015年 | 118篇 |
2014年 | 170篇 |
2013年 | 443篇 |
2012年 | 209篇 |
2011年 | 209篇 |
2010年 | 163篇 |
2009年 | 266篇 |
2008年 | 281篇 |
2007年 | 271篇 |
2006年 | 221篇 |
2005年 | 195篇 |
2004年 | 185篇 |
2003年 | 129篇 |
2002年 | 118篇 |
2001年 | 99篇 |
2000年 | 100篇 |
1999年 | 87篇 |
1998年 | 83篇 |
1997年 | 80篇 |
1996年 | 63篇 |
1995年 | 48篇 |
1994年 | 59篇 |
1993年 | 37篇 |
1992年 | 49篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 29篇 |
1988年 | 16篇 |
1987年 | 24篇 |
1986年 | 24篇 |
1985年 | 12篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 14篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1974年 | 5篇 |
排序方式: 共有4769条查询结果,搜索用时 15 毫秒
31.
32.
Jean MAWHIN 《数学年刊B辑(英文版)》2017,38(2):563-578
The existence of a zero for a holomorphic functions on a ball or on a rectangle under some sign conditions on the boundary generalizing Bolzano's ones for real functions on an interval is deduced in a very simple way from Cauchy's theorem for holomorphic functions.A more complicated proof,using Cauchy's argument principle,provides uniqueness of the zero,when the sign conditions on the boundary are strict.Applications are given to corresponding Brouwer fixed point theorems for holomorphic functions.Extensions to holomorphic mappings from Cn to Cn are obtained using Brouwer degree. 相似文献
33.
Tadeusz ANTCZAK 《数学物理学报(B辑英文版)》2017,37(4):1133-1150
In this paper, both Fritz John and Karush-Kuhn-Tucker necessary optimality conditions are established for a (weakly) LU-efficient solution in the considered nonsmooth multiobjective programming problem with the multiple interval-objective function. Further, the sufficient optimality conditions for a (weakly) LU-efficient solution and several duality results in Mond-Weir sense are proved under assumptions that the functions constituting the considered nondifferentiable multiobjective programming problem with the multiple interval-objective function are convex. 相似文献
34.
In the present paper, we consider elliptic equations with nonlinear and nonhomogeneous Robin boundary conditions of the type{-div(B(x, u)▽u) = f in ?,u = 0 on Γ_0,B(x, u)▽u·n→+γ(x)h(u) =g on Γ_1,where f and g are the element of L~1(?) and L~1(Γ_1), respectively. We define a notion of renormalized solution and we prove the existence of a solution. Under additional assumptions on the matrix field B we show that the renormalized solution is unique. 相似文献
35.
In this note, we explore the validity of Wente-type estimates for Neumann boundary problems involving Jacobians. We show in particular that such estimates do not in general hold under the same hypotheses on the data for Dirichlet boundary problems. 相似文献
36.
灰色GM(1,1)模型研究综述 总被引:6,自引:2,他引:4
GM(1,1)是灰色预测理论的核心模型和基础模型.从累加生成方法、初值优化、背景值优化、参数估计方法、模型性质和模型拓展的视角,梳理了GM(1,1)模型的研究进展.明确了有待进一步研究的问题,对GM(1,1)模型的未来研究方向提出了建议. 相似文献
37.
Visible light induced decomposition of sulfonyl hydrazides using Pd/ZrO2 nanocomposite photocatalyst
A new approach to synthesis of thiosulfonates has been developed under mild conditions without any oxidants and promoting reagents through a Pd/ZrO2 nanocomposite photocatalyst catalyzed decomposition of sulfonyl hydrazides. This protocol gave the products in moderate yields, comparable to the best results reported so far. Finally, a plausible reaction mechanism was proposed. 相似文献
38.
Solvent-free and high yielding one-pot synthesis of 1,8-dioxodecahydroacridine and polyhydroquinoline derivatives have been described through Hantzsch condensation of various aldehydes, ammonium acetate with cyclic 1,3-dicarbonyl compounds and ethyl acetoacetate in a very simple, efficient, and environmentally benign method using ascorbic acid as a nontoxic organocatalyst. 相似文献
39.
《Angewandte Chemie (International ed. in English)》2017,56(1):409-412
Heteroaromatic sulfoxides are a frequent structural motif in natural products, drugs, catalysts, and materials. We report a metal‐free visible‐light‐accelerated synthesis of heteroaromatic sulfoxides from sulfinamides and peroxodisulfate. The reaction proceeds at room temperature with blue‐light irradiation and allows the C−H sulfinylation of electron‐rich heteroarenes, such as pyrroles and indoles. An electrophilic aromatic substitution mechanism is proposed based on the substrate scope, substitution selectivity, and competition experiments with different nucleophiles. 相似文献
40.
General decay of solutions of a wave equation with memory term and acoustic boundary condition 下载免费PDF全文
In this paper, the global solvability to the mixed problem involving the wave equation with memory term and acoustic boundary conditions for non‐locally reacting boundary is considered. Moreover, the general decay of the energy functionality is established by the techniques of Messaoudi. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献