全文获取类型
收费全文 | 18012篇 |
免费 | 2472篇 |
国内免费 | 1676篇 |
专业分类
化学 | 1225篇 |
晶体学 | 144篇 |
力学 | 2504篇 |
综合类 | 335篇 |
数学 | 12797篇 |
物理学 | 5155篇 |
出版年
2024年 | 26篇 |
2023年 | 162篇 |
2022年 | 222篇 |
2021年 | 295篇 |
2020年 | 419篇 |
2019年 | 444篇 |
2018年 | 422篇 |
2017年 | 542篇 |
2016年 | 590篇 |
2015年 | 402篇 |
2014年 | 797篇 |
2013年 | 1288篇 |
2012年 | 829篇 |
2011年 | 960篇 |
2010年 | 912篇 |
2009年 | 1152篇 |
2008年 | 1169篇 |
2007年 | 1305篇 |
2006年 | 1140篇 |
2005年 | 1097篇 |
2004年 | 932篇 |
2003年 | 1002篇 |
2002年 | 889篇 |
2001年 | 697篇 |
2000年 | 702篇 |
1999年 | 662篇 |
1998年 | 528篇 |
1997年 | 500篇 |
1996年 | 309篇 |
1995年 | 242篇 |
1994年 | 194篇 |
1993年 | 183篇 |
1992年 | 144篇 |
1991年 | 118篇 |
1990年 | 98篇 |
1989年 | 65篇 |
1988年 | 76篇 |
1987年 | 59篇 |
1986年 | 48篇 |
1985年 | 77篇 |
1984年 | 76篇 |
1983年 | 39篇 |
1982年 | 52篇 |
1981年 | 59篇 |
1980年 | 42篇 |
1979年 | 43篇 |
1978年 | 46篇 |
1977年 | 37篇 |
1976年 | 23篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 298 毫秒
1.
2.
在完备的度量空间中,讨论了一类新型的非线性压缩映射ρ(Tx,Ty)≤a(ρ(x,y))ρ(x,Tx)+b(ρ(x,y))ρ(y,Ty)+c(ρ(x,y))ρ(x,y)通过构造迭代序列,指出该映射的不动点的存在性和唯一性,并给出相应的误差估计式,拓展和改进了有关文献的范围. 相似文献
3.
M. Amar D. Andreucci R. Gianni C. Timofte 《Journal of Mathematical Analysis and Applications》2021,493(2):124533
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation. 相似文献
4.
Clemens G. Raab Georg Regensburger Jamal Hossein Poor 《Journal of Pure and Applied Algebra》2021,225(5):106564
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials. 相似文献
5.
6.
《Mendeleev Communications》2022,32(4):507-509
We report on the synthesis of new Ru(bpy)2(phen) catalyst for the oscillatory Belousov–Zhabotinsky chemical reaction and on the preparation of novel Ru(bpy)2(phen)-based self-oscillating gels. The synthesized gels exhibit high-amplitude autonomous mechanical oscillations when the Belousov–Zhabotinsky reaction proceeds inside these gels 相似文献
7.
In this article, we construct and analyze a residual-based a posteriori error estimator for a quadratic finite volume method (FVM) for solving nonlinear elliptic partial differential equations with homogeneous Dirichlet boundary conditions. We shall prove that the a posteriori error estimator yields the global upper and local lower bounds for the norm error of the FVM. So that the a posteriori error estimator is equivalent to the true error in a certain sense. Numerical experiments are performed to illustrate the theoretical results. 相似文献
8.
9.
An electromechanical integrated electrostatic harmonic actuator is promising for the miniaturization of electromechanical devices. As the dimensions of the actuator decrease, the effects of the van der Waals force become obvious. In this study, by considering the nonlinearity of electrostatic and van der Waals forces, nonlinear vibration equations of the flexible ring of an electrostatic harmonic actuator are deduced. Using these equations, the nonlinear free vibration and nonlinear forced response of the actuator are investigated. The effects of the van der Waals force on the nonlinear vibration of the flexible ring are analyzed. Results show that these effects of the van der Waals force are relatively obvious under some conditions and should be considered. 相似文献
10.