全文获取类型
收费全文 | 16630篇 |
免费 | 1151篇 |
国内免费 | 914篇 |
专业分类
化学 | 668篇 |
晶体学 | 12篇 |
力学 | 2726篇 |
综合类 | 192篇 |
数学 | 13489篇 |
物理学 | 1608篇 |
出版年
2024年 | 34篇 |
2023年 | 158篇 |
2022年 | 191篇 |
2021年 | 246篇 |
2020年 | 365篇 |
2019年 | 365篇 |
2018年 | 426篇 |
2017年 | 454篇 |
2016年 | 447篇 |
2015年 | 336篇 |
2014年 | 686篇 |
2013年 | 1322篇 |
2012年 | 732篇 |
2011年 | 861篇 |
2010年 | 756篇 |
2009年 | 1032篇 |
2008年 | 1086篇 |
2007年 | 1124篇 |
2006年 | 1011篇 |
2005年 | 811篇 |
2004年 | 720篇 |
2003年 | 760篇 |
2002年 | 652篇 |
2001年 | 509篇 |
2000年 | 517篇 |
1999年 | 455篇 |
1998年 | 418篇 |
1997年 | 382篇 |
1996年 | 322篇 |
1995年 | 247篇 |
1994年 | 182篇 |
1993年 | 157篇 |
1992年 | 153篇 |
1991年 | 131篇 |
1990年 | 98篇 |
1989年 | 54篇 |
1988年 | 47篇 |
1987年 | 49篇 |
1986年 | 59篇 |
1985年 | 65篇 |
1984年 | 62篇 |
1983年 | 31篇 |
1982年 | 48篇 |
1981年 | 31篇 |
1980年 | 24篇 |
1979年 | 22篇 |
1978年 | 16篇 |
1977年 | 16篇 |
1976年 | 10篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
A high‐order element‐based Galerkin method is developed to solve the non‐divergent barotropic vorticity equation (BVE). The solution process involves solving a conservative transport equation for the vorticity fields and a Poisson equation for the stream function fields. The discontinuous Galerkin method is employed for solving the transport equation and a spectral element method (continuous Galerkin) is used for the Poisson equation. A third‐order strong stability preserving explicit Runge–Kutta scheme is used for time integration. A series of tests have been performed to validate the model, which include the evolution of an idealized tropical cyclone and interaction of dual vortices in close proximity. The numerical convergence study is performed by solving the BVE on the sphere where the analytic solution is known. The test results are consistent with physical observations, and the model exhibits exponential convergence. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
952.
利用不动点指数理论研究奇异二阶周期边值问题.在有关其线性算子方程对应的第一特征值的条件下得到边值问题正解的存在性,推广和改进了最近文献的结果. 相似文献
953.
Lin Juan Wang Chuanrong 《Annals of Differential Equations》2008,(3):283-288
In this paper, we discuss the stability of general compound boundary value prob-lems combining Riemann boundary value problem for an open arc and Hilbert bound-ary value problem for a unit circle with respect to the perturbation of boundary curve. 相似文献
954.
本文提出一种求解美式期权定价自由边值问题的变网格差分方法.通过建立一个自由边界所满足的方程,利用变网格技术可同时求出期权的差分解和最佳执行边界.本文分别讨论了显式和隐式变网格差分格式,并给出了差分解的收敛性和稳定性分析.数值实验表明本文算法是一个非常有效的期权定价算法. 相似文献
955.
In this paper, homotopy perturbation method (HPM) and variational iteration method (VIM) are applied to solve nonlinear oscillator
differential equations. Illustrative examples reveal that these methods are very effective and convenient for solving nonlinear
differential equations. Moreover, the methods do not require linearization or small perturbation. Comparisons are also made
between the exact solutions and the results of the homotopy perturbation method and variational iteration method in order
to prove the precision of the results obtained from both methods mentioned. 相似文献
956.
In this paper, we introduce an iteration scheme given by finite nonexpansive mappings in Banach spaces and then prove weak convergence theorems which are connected with the problem of image recovery. Using the results, we consider the problem of finding a common fixed point of finite nonexpansive mappings. 相似文献
957.
We propose a novel approach for solving polynomial programs over compact domains with equality constraints. By means of a generic transformation, we show that existing solution schemes for the, typically simpler, problem without equalities can be used to address the problem with equalities. 相似文献
958.
This paper concerns with properties of solutions of a nonlinear diffusion problem in non-divergence form.By constructing proper test functions,it is proved that solutions of the problem possess the property of localization. 相似文献
959.
Michael Lukaschewitsch Peter Maass Michael Pidcock Cristiana Sebu 《Mathematical Methods in the Applied Sciences》2009,32(2):206-222
The forward problem of electrical impedance tomography on unbounded domains can be studied by introducing appropriate function spaces for this setting. In this paper we derive the point‐wise asymptotic behaviour of weak solutions to this problem in the three‐dimensional case. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
960.
This paper furnishes several closed-form solutions for the buckling eigenvalue problem of the columns with variable flexural rigidity along the axis. The column is either under uniformly distributed axial load or under concentrated compressive load.
Sommario. Questo lavoro fornisce diverse soluzioni in forma chiusa per il problema agli autovalori dell'instabilità di colonne con rigidezza flessionale variabile lungo l'asse. La colonna è soggetta ad un carico assiale unifor-memente distribuito oppure ad una forza di compressione concentrata. 相似文献