全文获取类型
收费全文 | 26195篇 |
免费 | 1953篇 |
国内免费 | 1180篇 |
专业分类
化学 | 3684篇 |
晶体学 | 43篇 |
力学 | 2978篇 |
综合类 | 170篇 |
数学 | 17175篇 |
物理学 | 5278篇 |
出版年
2024年 | 60篇 |
2023年 | 340篇 |
2022年 | 426篇 |
2021年 | 563篇 |
2020年 | 840篇 |
2019年 | 775篇 |
2018年 | 796篇 |
2017年 | 802篇 |
2016年 | 751篇 |
2015年 | 690篇 |
2014年 | 1239篇 |
2013年 | 2931篇 |
2012年 | 1189篇 |
2011年 | 1515篇 |
2010年 | 1210篇 |
2009年 | 1733篇 |
2008年 | 1713篇 |
2007年 | 1503篇 |
2006年 | 1300篇 |
2005年 | 1080篇 |
2004年 | 934篇 |
2003年 | 820篇 |
2002年 | 790篇 |
2001年 | 604篇 |
2000年 | 633篇 |
1999年 | 597篇 |
1998年 | 493篇 |
1997年 | 470篇 |
1996年 | 377篇 |
1995年 | 252篇 |
1994年 | 234篇 |
1993年 | 193篇 |
1992年 | 154篇 |
1991年 | 119篇 |
1990年 | 101篇 |
1989年 | 84篇 |
1988年 | 63篇 |
1987年 | 67篇 |
1986年 | 57篇 |
1985年 | 106篇 |
1984年 | 140篇 |
1983年 | 67篇 |
1982年 | 88篇 |
1981年 | 89篇 |
1980年 | 72篇 |
1979年 | 73篇 |
1978年 | 63篇 |
1977年 | 40篇 |
1976年 | 34篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
21.
22.
Deborah M. Greaves 《国际流体数值方法杂志》2006,50(6):693-711
An adaptive hierarchical grid‐based method for predicting complex free surface flows is used to simulate collapse of a water column. Adapting quadtree grids are combined with a high‐resolution interface‐capturing approach and pressure‐based coupling of the Navier–Stokes equations. The Navier–Stokes flow solution scheme is verified for simulation of flow in a lid‐driven cavity at Re=1000. Two approaches to the coupling of the Navier–Stokes equations are investigated as are alternative face velocity and hanging node interpolations. Collapse of a water column as well as collapse of a water column and its subsequent interaction with an obstacle are simulated. The calculations are made on uniform and adapting quadtree grids, and the accuracy of the quadtree calculations is shown to be the same as those made on the equivalent uniform grids. Results are in excellent agreement with experimental and other numerical data. A sharp interface is maintained at the free surface. The new adapting quadtree‐based method achieves a considerable saving in the size of the computational grid and CPU time in comparison with calculations made on equivalent uniform grids. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
23.
We treat here of the question of absorbing boundary conditionsfor nonlinear diffusion equations. We use the conditions designedfor the linear equation, we prove them to be well posed forthe nonlinear problem, and through numerical experiments thatthey are well suited for reactiondiffusion equations. 相似文献
24.
Frank Jochmann 《Journal of Differential Equations》2004,203(2):232-254
In this paper, Maxwell's equations involving generally nonlinear polarization and field-dependent currents are studied. The main objective is the asymptotic behavior of the solution for t→∞ if no damping term occurs in the equation governing the polarization field. 相似文献
25.
Reaction of acetylene dicarboxaldehyde monoacetal with substituted Meldrum’s acid leads good yields in 2-pyranones-4-carboxaldehydes substituted in position 3. 相似文献
26.
Hiroto Kudo Nobuhito Ito Keiji Nakajima Masami Ochiai Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(19):4421-4429
The polyaddition of fluorine‐containing bis(epoxide)s and fluorine‐containing triazine di(aryl ether)s were examined to give the corresponding fluorine‐containing poly(cyanurate)s. It was observed that the synthesized fluoropolymers had good thermal stabilities and good film‐forming properties. The glass transition temperatures (Tg's) and refractive‐indices (nD's) of synthesized polymers were determined by differential scanning calorimetry and ellipsometry, respectively, and it was found that the values of Tg's and nD's were supported by their fluorine containing ratios and skeletons. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4421–4429, 2007 相似文献
27.
Svitlana P. Rogovchenko 《Journal of Mathematical Analysis and Applications》2003,279(1):121-134
In this paper, we are concerned with a class of nonlinear second-order differential equations with a nonlinear damping term. Passage to more general class of equations allows us to remove a restrictive condition usually imposed on the nonlinearity, and, as a consequence, our results apply to wider classes of nonlinear differential equations. Two illustrative examples are considered. 相似文献
28.
Karl Gustafson 《Numerical Linear Algebra with Applications》2004,11(7):649-659
Given the operator product BA in which both A and B are symmetric positive‐definite operators, for which symmetric positive‐definite operators C is BA symmetric positive‐definite in the C inner product 〈x, y〉C? This question arises naturally in preconditioned iterative solution methods, and will be answered completely here. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
29.
An exact formalism for the relativistic version of Landau theory of Fermi liquid in presence of strong quantizing magnetic field is developed. Both direct and exchange type interactions with scalar and vector coupling cases are considered. 相似文献
30.
In this Letter we consider the Abelian Chern–Simons vortices on a bounded simply connected domain. We establish the existence of solutions for the self-duality equations. We prove the uniqueness of solutions when all the vortex points are equal and the domain is star-shaped. We also show the radial symmetry of solutions on balls centered at the vortex point. 相似文献