全文获取类型
收费全文 | 4524篇 |
免费 | 421篇 |
国内免费 | 404篇 |
专业分类
化学 | 506篇 |
晶体学 | 11篇 |
力学 | 646篇 |
综合类 | 108篇 |
数学 | 3384篇 |
物理学 | 694篇 |
出版年
2024年 | 5篇 |
2023年 | 55篇 |
2022年 | 62篇 |
2021年 | 61篇 |
2020年 | 101篇 |
2019年 | 124篇 |
2018年 | 141篇 |
2017年 | 148篇 |
2016年 | 165篇 |
2015年 | 147篇 |
2014年 | 224篇 |
2013年 | 370篇 |
2012年 | 213篇 |
2011年 | 266篇 |
2010年 | 201篇 |
2009年 | 277篇 |
2008年 | 307篇 |
2007年 | 298篇 |
2006年 | 263篇 |
2005年 | 245篇 |
2004年 | 221篇 |
2003年 | 209篇 |
2002年 | 185篇 |
2001年 | 138篇 |
2000年 | 140篇 |
1999年 | 126篇 |
1998年 | 111篇 |
1997年 | 80篇 |
1996年 | 79篇 |
1995年 | 51篇 |
1994年 | 65篇 |
1993年 | 35篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 20篇 |
1983年 | 5篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 12篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有5349条查询结果,搜索用时 187 毫秒
101.
Existence and non-existence results are established for quasilinear elliptic problems with nonlinear boundary conditions and lack of compactness. The proofs combine variational methods with the geometrical feature, due to the competition between the different growths of the nonlinearities. 相似文献
102.
Winfried Teschner 《基于设计的结构力学与机械力学》2013,41(4):491-500
The application of optimal control theory to minimum weight design of continuous one-dimensional structural elements subject to eigenvalue constraints is discussed. If not only the value of an eigenvalue is prescribed but also its position in the sequence of the ordered eigenvalues—for example, the critical buckling load of a column—the corresponding optimal control problem is shown to include necessarily all eigenvalues. Considering the unspecified eigenvalues as free parameters, necessary conditions for minimum weight design are derived. These conditions are compared with those obtained by use of variational methods. Attention is focused on the special case of multimodal solutions. 相似文献
103.
The stability and accuracy of radiation type non‐reflective outflow boundary conditions, as well as the standard Neumann boundary condition with zero normal derivative, have been compared for the numerical simulation of a turbulent axisymmetric plume with Reynolds number of 7700 and Prandtl number of 0.71. Comparison of the performance of the boundary conditions with respect to each other, and to the results obtained for an extended domain, shows that a one‐dimensional scheme in which advection and diffusion terms are included in the radiation equation is the optimum approach for the plume simulation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
104.
对二元函数连续性判定条件给出了详细分析,强调有关问题的关键点,纠正了常见的模糊认识,得到一系列连续性充分条件及其推广形式. 相似文献
105.
《Optimization》2012,61(11):2277-2287
Two adaptive choices for the parameter of Dai–Liao conjugate gradient (CG) method are suggested. One of which is obtained by minimizing the distance between search directions of Dai–Liao method and a three-term CG method proposed by Zhang et al. and the other one is obtained by minimizing Frobenius condition number of the search direction matrix. Global convergence analyses are made briefly. Numerical results are reported; they demonstrate effectiveness of the suggested adaptive choices. 相似文献
106.
By taking the coupling effect into consideration, we study the resonance condition of a photonic wire microring resonator (PWRR) sensor and compare our results with the previous work. Simulation results show that the resonant wavelength and sensitivity strongly depend on the coupling strength. The difference caused by the coupling effect can be up to tens of nanometers for the resonant peak position and tens of nm/RIU for the sensitivity in a silicon-on-insulator (SOI) PWRR. Such a giant influence from coupling effect cannot be disregarded and should be considered seriously for the design and application of PWRRs. It also shows an alternative tuning technique by controlling the coupling strength. 相似文献
107.
The problem of finding the plane supporting curve (brachistochrone) along which a heavy particle released from rest at the given starting point slides with dry (Coulomb) friction and reaches the given destination point in least time, is stated as a variational isoperimetrical problem. The finite parametric equations of the extremal curve are obtained. This curve is the sought-for brachistochrone if the solution of the problem exists. Several numerical examples are given. 相似文献
108.
In this paper we study the nonlinear Chern–Simons–Schrödinger systems with an external potential. We show the existence, non-existence, and multiplicity of standing waves to this problem with asymptotically linear nonlinearities, which do not hold the Ambrosetti–Rabinowitz condition. 相似文献
109.
For nonlinear Schrödinger equations in less than or equal to four dimension, with non-vanishing initial data at infinity, a new approach to derive the conservation law is obtained. Since this approach does not contain approximating procedure, the argument is simplified and some of technical assumption of the nonlinearity to derive the conservation law and time global solutions, is removed. 相似文献
110.
《Applied Mathematical Modelling》2014,38(5-6):1607-1611
In this paper, He’s homotopy perturbation method (HPM) is applied for solving linear programming (LP) problems. This paper shows that some recent findings about this topic cannot be applied for all cases. Furthermore, we provide the correct application of HPM for LP problems. The proposed method has a simple and graceful structure. Finally, a numerical example is displayed to illustrate the proposed method. 相似文献