全文获取类型
收费全文 | 5612篇 |
免费 | 251篇 |
国内免费 | 32篇 |
专业分类
化学 | 3453篇 |
晶体学 | 23篇 |
力学 | 192篇 |
数学 | 1196篇 |
物理学 | 1031篇 |
出版年
2023年 | 55篇 |
2022年 | 52篇 |
2021年 | 163篇 |
2020年 | 156篇 |
2019年 | 153篇 |
2018年 | 129篇 |
2017年 | 116篇 |
2016年 | 242篇 |
2015年 | 229篇 |
2014年 | 240篇 |
2013年 | 337篇 |
2012年 | 413篇 |
2011年 | 464篇 |
2010年 | 271篇 |
2009年 | 247篇 |
2008年 | 374篇 |
2007年 | 338篇 |
2006年 | 309篇 |
2005年 | 297篇 |
2004年 | 232篇 |
2003年 | 176篇 |
2002年 | 161篇 |
2001年 | 49篇 |
2000年 | 32篇 |
1999年 | 44篇 |
1998年 | 42篇 |
1997年 | 54篇 |
1996年 | 40篇 |
1995年 | 46篇 |
1994年 | 45篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 22篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1973年 | 8篇 |
1972年 | 5篇 |
排序方式: 共有5895条查询结果,搜索用时 15 毫秒
81.
82.
Bergner Martin Caprara Alberto Ceselli Alberto Furini Fabio Lübbecke Marco E. Malaguti Enrico Traversi Emiliano 《Mathematical Programming》2015,149(1-2):391-424
Mathematical Programming - Dantzig–Wolfe decomposition (or reformulation) is well-known to provide strong dual bounds for specially structured mixed integer programs (MIPs). However, the... 相似文献
83.
84.
85.
86.
87.
88.
David C. Thvenaz Soo Hyon Lee Florian Guignard Sandor Balog Marco Lattuada Christoph Weder Yoan C. Simon 《Macromolecular rapid communications》2016,37(10):826-832
Low‐power light upconversion is a highly desirable feature for a broad range of applications and new materials enabling this process are sought in both bulk and particulate form. Here, the preparation of upconverting nanoparticles is reported from a methacrylic terpolymer bearing diphenylanthracene and meso‐phenoxytris(heptyl)porphyrin pendant groups by a microemulsion technique. The use of a terpolymer in which the upconvering dye molecules are covalently attached mitigates some of the drawbacks of triplet–triplet annihilation upconverting nanoparticles made by other techniques, in particular dye leakage from the nanoparticles, and limited control of the sensitizer and emitter concentration within each nanoparticle. Size and morphology of the new upconverting nanoparticles are investigated by dynamic light scattering and transmission electron microscopy and elucidated their upconverting properties by luminescence spectroscopy.
89.
Jaume Llibre Paulo R. da Silva Marco A. Teixeira 《Journal of Dynamics and Differential Equations》2007,19(2):309-331
Singular perturbations problems in dimension three which are approximations of discontinuous vector fields are studied in
this paper. The main result states that the regularization process developed by Sotomayor and Teixeira produces a singular
problem for which the discontinuous set is a center manifold. Moreover, the definition of sliding vector field coincides with
the reduced problem of the corresponding singular problem for a class of vector fields.
相似文献
90.
We show how to formulate two-point boundary-value problems in order to compute fully-developed laminar channel and tube flow profiles for viscoelastic fluid models. The formulation is applied to Couette and pressure-driven flows separately, or a combination of both. The application of this methodology is illustrated analytically for the Upper-Convected Maxwell Model, and it is applied computationally for the Phan-Thien/Tanner and Giesekus Models. Numerical solutions exist for the last two models [J.Y. Yoo, H.C. Choi, On the steady simple shear flows of the one-mode Giesekus fluid, Rheol. Acta 28 (1989) 13–24; P.J. Oliveira, F.T. Pinho, Analytical solution for fully developed channel and pipe flow of Phan-Thien–Tanner fluids, J. Fluid Mech. 387 (1999) 271–280; M.A. Alves, F.T. Pinho, P.J. Oliveira, Study of steady pipe and channel flows of a single-mode Phan-Thien–Tanner fluid, J. Non-Newtonian Fluid Mech. 101 (2001) 55–76], allowing verification of the computational technique. Subsequently, the computational algorithm is applied to the constant-volume polymer blend models of Maffettone and Minale [P.L. Maffettone, M. Minale, Equation of change for ellipsoidal drops in viscous flow, J. Non-Newtonian Fluid Mech. 84 (1999) 105–106 (Erratum), J. Non-Newtonian Fluid Mech. 78 (1998) 227–241] and Dressler and Edwards [M. Dressler, B.J. Edwards, The influence of matrix viscoelasticity on the rheology of polymer blends, Rheol. Acta 43 (2004) 257–282; M. Dressler, B.J. Edwards, Rheology of polymer blends with matrix-phase viscoelasticity and a narrow droplet size distribution, J. Non-Newtonian Fluid Mech. 120 (2004) 189–205]. Rheological and morphological properties of the model blends are thus obtained as functions of the spatial position within the channel, applied pressure drop, and shear rate at the wall. 相似文献