全文获取类型
收费全文 | 8087篇 |
免费 | 743篇 |
国内免费 | 1089篇 |
专业分类
化学 | 7428篇 |
晶体学 | 71篇 |
力学 | 700篇 |
综合类 | 121篇 |
数学 | 559篇 |
物理学 | 1040篇 |
出版年
2024年 | 9篇 |
2023年 | 101篇 |
2022年 | 254篇 |
2021年 | 254篇 |
2020年 | 328篇 |
2019年 | 308篇 |
2018年 | 312篇 |
2017年 | 479篇 |
2016年 | 532篇 |
2015年 | 447篇 |
2014年 | 468篇 |
2013年 | 536篇 |
2012年 | 580篇 |
2011年 | 550篇 |
2010年 | 485篇 |
2009年 | 464篇 |
2008年 | 381篇 |
2007年 | 465篇 |
2006年 | 413篇 |
2005年 | 339篇 |
2004年 | 304篇 |
2003年 | 252篇 |
2002年 | 249篇 |
2001年 | 188篇 |
2000年 | 191篇 |
1999年 | 166篇 |
1998年 | 133篇 |
1997年 | 139篇 |
1996年 | 137篇 |
1995年 | 110篇 |
1994年 | 92篇 |
1993年 | 37篇 |
1992年 | 28篇 |
1991年 | 26篇 |
1990年 | 33篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1976年 | 3篇 |
1971年 | 1篇 |
1959年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有9919条查询结果,搜索用时 15 毫秒
31.
Nash Equilibria,Variational Inequalities,and Dynamical Systems 总被引:2,自引:0,他引:2
Cavazzuti E. Pappalardo M. Passacantando M. 《Journal of Optimization Theory and Applications》2002,114(3):491-506
In this paper, we introduce some relationships between Nash equilibria, variational equilibria, and dynamical equilibria for noncooperative games. 相似文献
32.
Analysis of Static Simulated Annealing Algorithms 总被引:1,自引:0,他引:1
Generalized hill climbing (GHC) algorithms provide a framework for modeling local search algorithms to address intractable discrete optimization problems. This paper introduces a measure for determining the expected number of iterations to visit a predetermined objective function level, given that an inferior objective function level has been reached in a finite number of iterations. A variation of simulated annealing (SA), termed static simulated annealing (S2A), is analyzed using this measure. S2A uses a fixed cooling schedule during the algorithm execution. Though S2A is probably nonconvergent, its finite-time performance can be assessed using the finite-time performance measure defined in this paper. 相似文献
33.
34.
给定一组工件的加工时间与工期,要求确定这些工件在一台机器上的加.工排列,使相应的总延误达到最小,这就是总延误问题.该问题在近年已被证明是NP困难的.由Wilkermn和Irwin(1971),林勋(1983)等所研究的顺时安排法能得到相邻交换意义下的局部解.在本文中,我们进一步证明该算法能得到前移邻域意义下的局部解,并确定了该算法的性能比. 相似文献
35.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(13):3419-3419
36.
37.
V. I. Grabovskii 《Fluid Dynamics》2003,38(2):193-202
The optimum shape of the cylindrical internal deformable (flexible) surface of a gas journal bearing of infinite length is designed. The variational problem of determining the clearance shape giving the maximum bearing load capacity is formulated and solved. 相似文献
38.
39.
A method is developed for performing a local reduction of the governing physics for fluid problems with domains that contain a combination of narrow and non‐narrow regions, and the computational accuracy and performance of the method are measured. In the narrow regions of the domain, where the fluid is assumed to have no inertia and the domain height and curvature are assumed small, lubrication, or Reynolds, theory is used locally to reduce the two‐dimensional Navier–Stokes equations to the one‐dimensional Reynolds equation while retaining a high degree of accuracy in the overall solution. The Reynolds equation is coupled to the governing momentum and mass equations of the non‐narrow region with boundary conditions on the mass and momentum flux. The localized reduction technique, termed ‘stitching,’ is demonstrated on Stokes flow for various geometries of the hydrodynamic journal bearing—a non‐trivial test problem for which a known analytical solution is available. The computational advantage of the coupled Stokes–Reynolds method is illustrated on an industrially applicable fully‐flooded deformable‐roll coating example. The examples in this paper are limited to two‐dimensional Stokes flow, but extension to three‐dimensional and Navier–Stokes flow is possible. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
40.
Yoshitomo Ono Naoyuki Kawashima Hiroto Kudo Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2007,45(14):2978-2988
The ring‐opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor–acceptor norbornadiene (D‐A NBD) dicarboxylic acid, 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid, monoglycidyl ester derivatives with D‐A NBD dicarboxylic anhydride using tetraphenylphosphonium bromide as a catalyst proceeded smoothly to give novel self‐photosensitizing NBD polymers in good yields. The molecular weight of these polyesters was about 4,000, and lower than that of analogous NBD polymers having no benzophenone group. All the synthesized NBD polymers isomerized smoothly to the corresponding quadricyclane (QC) polymers upon UV irradiation in tetrahydrofuran (THF) solution and in the film state. The rate of the photoisomerization of the D‐A NBD moieties in these polymers was higher than that of the D‐A NBD moieties in the polymer having no photosensitizing group. Furthermore, the rate of the photoisomerization of the D‐A NBD moieties in these polymers was also higher than that of the NBD polymer with low molecular weight photosensitizer in dilute solution. The photo‐irradiated polymers having QC moieties released thermal energies of 146–180 J/g. The D‐A NBD moieties contained in these NBD polymers possessed fair to good fatigue resistance. The degradation of the NBD moieties in these polymers was 15–30% after 50 repeated cycles of interconversion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2978–2988, 2007 相似文献