全文获取类型
收费全文 | 5592篇 |
免费 | 581篇 |
国内免费 | 512篇 |
专业分类
化学 | 653篇 |
晶体学 | 8篇 |
力学 | 655篇 |
综合类 | 154篇 |
数学 | 4277篇 |
物理学 | 938篇 |
出版年
2024年 | 12篇 |
2023年 | 47篇 |
2022年 | 102篇 |
2021年 | 133篇 |
2020年 | 135篇 |
2019年 | 112篇 |
2018年 | 149篇 |
2017年 | 164篇 |
2016年 | 195篇 |
2015年 | 124篇 |
2014年 | 226篇 |
2013年 | 480篇 |
2012年 | 268篇 |
2011年 | 308篇 |
2010年 | 278篇 |
2009年 | 353篇 |
2008年 | 337篇 |
2007年 | 363篇 |
2006年 | 295篇 |
2005年 | 282篇 |
2004年 | 292篇 |
2003年 | 262篇 |
2002年 | 242篇 |
2001年 | 180篇 |
2000年 | 177篇 |
1999年 | 194篇 |
1998年 | 148篇 |
1997年 | 145篇 |
1996年 | 89篇 |
1995年 | 83篇 |
1994年 | 69篇 |
1993年 | 69篇 |
1992年 | 62篇 |
1991年 | 50篇 |
1990年 | 41篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 10篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 3篇 |
排序方式: 共有6685条查询结果,搜索用时 15 毫秒
831.
本文研究一类带Neumann 边界条件的~$p(x)$-Kirchhoff 型系统解的存在性. 借助于Ekeland变分原理和变指数Sobolev空间理论, 我们给出使得该问题存在解的合适条件.由于Poincar\'{e} 不等式在$W^{1,p(x)}(\Omega)$ 中不再成立, 我们将在$W^{1,p(x)}(\Omega)$ 的某个子空间中证明Poincar\'{e}-Wirtinger 不等式. 相似文献
832.
In this paper, by using p-distances on uniform spaces, we establish a general vectorial Ekeland variational principle (in short EVP), where the objective function is defined on a uniform space and taking values in a pre-ordered real linear space and the perturbation involves a p-distance and a monotone function of the objective function. Since p-distances are very extensive, such a form of the perturbation in deed contains many different forms of perturbations appeared in the previous versions of EVP. Besides, we only require the objective function has a very weak property, as a substitute for lower semi-continuity, and only require the domain space (which is a uniform space) has a very weak type of completeness, i.e., completeness with respect to a certain p-distance. Such very weak type of completeness even includes local completeness when the uniform space is a locally convex topological vector space. From the general vectorial EVP, we deduce a general vectorial Caristi's fixed point theorem and a general vectorial Takahashi's nonconvex minimization theorem. Moreover, we show that the above three theorems are equivalent to each other. We see that the above general vectorial EVP includes many particular versions of EVP, which extend and complement the related known results. 相似文献
833.
Ke Bo Lu 《数学学报(英文版)》2013,29(11):2181-2192
In this paper, we study the combinatorial properties ol words m chscrete dynamical systems from antisymmetric cubic maps. We also discuss the relationship of primitive kneading sequences of length n and period-doubling kneading sequences of length 2n, and then determine the number of all kneading sequences of length n. 相似文献
834.
研究了一类随机适应序列的强极限定理,推广了最近发表的几个结果,并进一步推广了Borel—Cantelli引理. 相似文献
835.
Mark Holland Stefano Luzzatto § 《Journal of Difference Equations and Applications》2013,19(6):535-551
We introduce a new technique for proving the classical stable manifold theorem for hyperbolic fixed points. This method is much more geometrical than the standard approaches which rely on abstract fixed point theorems. It is based on the convergence of a canonical sequence of “finite time local stable manifolds” which are related to the dynamics of a finite number of iterations. 相似文献
836.
837.
Marek Galewski Renata Wieteska 《Journal of Difference Equations and Applications》2013,19(7):1065-1081
We investigate the existence of solutions of the system of anisotropic discrete boundary value problems using critical point theory. We apply direct variational approach, the Ky Fan min–max inequality and the mountain pass lemma. 相似文献
838.
Yen Chih Chang Gen-qiang Wang 《Journal of Difference Equations and Applications》2013,19(7):1133-1162
A nonlinear three-term recurrence relation arising from seeking the steady states of a cellular neural network with bang‐bang control is studied. We show that each solution is periodic and its prime period can be determined by three of its consecutive terms. By means of this periodicity property, we may then solve the steady state problem which to our knowledge is not solved by other means. 相似文献
839.
通过构造一组泛函,用变分迭代地方式研究了兰切斯特方程的各次近似解,这种近似解是解析解,还能继续进行各种解析运算.从而可进一步研究对兰切斯特方程进行定性及定量的研究. 相似文献
840.
Yueqiang Shang 《Numerical Methods for Partial Differential Equations》2013,29(6):2025-2046
A finite element variational multiscale method based on two local Gauss integrations is applied to solve numerically the time‐dependent incompressible Navier–Stokes equations. A significant feature of the method is that the definition of the stabilization term is derived via two local Guass integrations at element level, making it more efficient than the usual projection‐based variational multiscale methods. It is computationally cheap and gives an accurate approximation to the quantities sought. Based on backward Euler and Crank–Nicolson schemes for temporal discretization, we derive error bounds of the fully discrete solution which are first and second order in time, respectively. Numerical tests are also given to verify the theoretical predictions and demonstrate the effectiveness of the proposed method. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013 相似文献