全文获取类型
收费全文 | 12068篇 |
免费 | 1450篇 |
国内免费 | 823篇 |
专业分类
化学 | 2397篇 |
晶体学 | 58篇 |
力学 | 1349篇 |
综合类 | 181篇 |
数学 | 6838篇 |
物理学 | 3518篇 |
出版年
2024年 | 21篇 |
2023年 | 116篇 |
2022年 | 180篇 |
2021年 | 229篇 |
2020年 | 334篇 |
2019年 | 329篇 |
2018年 | 327篇 |
2017年 | 359篇 |
2016年 | 423篇 |
2015年 | 303篇 |
2014年 | 473篇 |
2013年 | 1072篇 |
2012年 | 538篇 |
2011年 | 650篇 |
2010年 | 553篇 |
2009年 | 665篇 |
2008年 | 741篇 |
2007年 | 756篇 |
2006年 | 697篇 |
2005年 | 634篇 |
2004年 | 614篇 |
2003年 | 521篇 |
2002年 | 470篇 |
2001年 | 412篇 |
2000年 | 424篇 |
1999年 | 350篇 |
1998年 | 286篇 |
1997年 | 300篇 |
1996年 | 201篇 |
1995年 | 214篇 |
1994年 | 162篇 |
1993年 | 142篇 |
1992年 | 123篇 |
1991年 | 107篇 |
1990年 | 80篇 |
1989年 | 49篇 |
1988年 | 49篇 |
1987年 | 50篇 |
1986年 | 49篇 |
1985年 | 54篇 |
1984年 | 45篇 |
1983年 | 27篇 |
1982年 | 41篇 |
1981年 | 23篇 |
1980年 | 25篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1977年 | 23篇 |
1974年 | 10篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Mendeleev Communications》2022,32(4):534-536
Correlation times and diffusion coefficients of water molecules were measured for the first time by 1H spin relaxation and pulsed field gradient NMR in Li+, Na+ and Cs+ ionic forms of Nafion 117 membrane. Hydration numbers of Li+, Na+ and Cs+ cations were calculated. It was shown that at high humidity macroscopic transfer is controlled by the local translational motion of water molecules. 相似文献
2.
3.
4.
This work is concerned with the extension of the Jacobi spectral Galerkin method to a class of nonlinear fractional pantograph differential equations. First, the fractional differential equation is converted to a nonlinear Volterra integral equation with weakly singular kernel. Second, we analyze the existence and uniqueness of solutions for the obtained integral equation. Then, the Galerkin method is used for solving the equivalent integral equation. The error estimates for the proposed method are also investigated. Finally, illustrative examples are presented to confirm our theoretical analysis. 相似文献
5.
6.
《Electroanalysis》2006,18(6):595-604
The following two numerical models have been applied to zinc cations electroreduction in 1 M NaClO4 water solution: a classical EE model describing the concentration of involved species in solution (semi infinitive diffusion region), an extended EE model describing both: the concentration of involved species in solution and the concentration of metallic zinc inside mercury drop (in limited area of diffusion). In the latter model the inner part of mercury drop and surrounding solution were treated as dynamic interrelated system. Both models were applied to experimental cyclic voltammetric CV data in 1 M NaClO4, the results compared and discussed. The concentration profiles of all species including metallic zinc inside mercury drop were performed. The presented integrated model is essential for theoretical and analytical aspects of the electrochemistry of mercury soluble metal cations and amalgams. 相似文献
7.
8.
9.
P.A. Ramachandran 《Numerical Methods for Partial Differential Equations》2006,22(4):831-846
Time‐dependent differential equations can be solved using the concept of method of lines (MOL) together with the boundary element (BE) representation for the spatial linear part of the equation. The BE method alleviates the need for spatial discretization and casts the problem in an integral format. Hence errors associated with the numerical approximation of the spatial derivatives are totally eliminated. An element level local cubic approximation is used for the variable at each time step to facilitate the time marching and the nonlinear terms are represented in a semi‐implicit manner by a local linearization at each time step. The accuracy of the method has been illustrated on a number of test problems of engineering significance. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2006 相似文献
10.
We analyze diffusion from a periodic array of hemispherical droplets through a membrane. We find that the multiple sources do not interact strongly, even when the droplets are closely spaced, so that the flux through the membrane appears nearly additive. 相似文献