全文获取类型
收费全文 | 21944篇 |
免费 | 861篇 |
国内免费 | 788篇 |
专业分类
化学 | 4578篇 |
晶体学 | 180篇 |
力学 | 614篇 |
综合类 | 107篇 |
数学 | 12522篇 |
物理学 | 5592篇 |
出版年
2023年 | 189篇 |
2022年 | 224篇 |
2021年 | 303篇 |
2020年 | 486篇 |
2019年 | 579篇 |
2018年 | 546篇 |
2017年 | 445篇 |
2016年 | 431篇 |
2015年 | 464篇 |
2014年 | 840篇 |
2013年 | 1465篇 |
2012年 | 683篇 |
2011年 | 1724篇 |
2010年 | 1192篇 |
2009年 | 1408篇 |
2008年 | 1594篇 |
2007年 | 1528篇 |
2006年 | 1194篇 |
2005年 | 1013篇 |
2004年 | 824篇 |
2003年 | 742篇 |
2002年 | 696篇 |
2001年 | 438篇 |
2000年 | 431篇 |
1999年 | 440篇 |
1998年 | 386篇 |
1997年 | 314篇 |
1996年 | 337篇 |
1995年 | 326篇 |
1994年 | 326篇 |
1993年 | 292篇 |
1992年 | 240篇 |
1991年 | 171篇 |
1990年 | 167篇 |
1989年 | 136篇 |
1988年 | 97篇 |
1987年 | 98篇 |
1986年 | 78篇 |
1985年 | 125篇 |
1984年 | 97篇 |
1983年 | 69篇 |
1982年 | 98篇 |
1981年 | 78篇 |
1980年 | 65篇 |
1979年 | 33篇 |
1978年 | 55篇 |
1977年 | 39篇 |
1976年 | 34篇 |
1975年 | 11篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
In this paper we prove that weak solutions to the Diffusive Wave Approximation of the Shallow Water equations are locally bounded. Here, u describes the height of the water, z is a given function that represents the land elevation and f is a source term accounting for evaporation, infiltration or rainfall. 相似文献
22.
23.
Ivan Bazhov 《Journal of Pure and Applied Algebra》2019,223(6):2530-2542
We study the similarities between the Fano varieties of lines on a cubic fourfold, a hyper-Kähler fourfold studied by Beauville and Donagi, and the hyper-Kähler fourfold constructed by Debarre and Voisin in [3]. We exhibit an analog of the notion of “triangle” for these varieties and prove that the 6-dimensional variety of “triangles” is a Lagrangian subvariety in the cube of the constructed hyper-Kähler fourfold. 相似文献
24.
Sameerah Jamal 《Journal of Differential Equations》2019,266(7):4018-4026
A manifold that contains small perturbations will induce a perturbed partial differential equation. The partial differential equation that we select is the Poisson equation – in order to explore the interplay between the geometry of the manifold and the perturbations. Specifically, we show how the problem of symmetry determination, for higher-order perturbations, can be elegantly expressed via geometric conditions. 相似文献
25.
Roshanak Hatamvand Azim Shams Ehsan Mohammadifar Abdollah Yari Mohsen Adeli 《Journal of polymer science. Part A, Polymer chemistry》2019,57(13):1430-1439
Despite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking advantage of the straightforward synthesis, cheap precursors and multifunctionality of poly(glycerol‐oligoγ‐butyrolactone)s, they could be used for real‐time sensing of a wide range of biosystems. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1430–1439 相似文献
26.
Tomasz Przebinda 《Journal of Functional Analysis》2018,274(5):1284-1305
We relate the distribution characters and the wave front sets of unitary representation for real reductive dual pairs of type I in the stable range. 相似文献
27.
28.
29.
Arne Van Antwerpen 《Journal of Pure and Applied Algebra》2018,222(11):3379-3394
In this paper, we show that all Coleman automorphisms of a finite group with self-central minimal non-trivial characteristic subgroup are inner; therefore the normalizer property holds for these groups. Using our methods we show that the holomorph and wreath product of finite simple groups, among others, have no non-inner Coleman automorphisms. As a further application of our theorems, we provide partial answers to questions raised by M. Hertweck and W. Kimmerle. Furthermore, we characterize the Coleman automorphisms of extensions of a finite nilpotent group by a cyclic p-group. Finally, we note that class-preserving Coleman automorphisms of p-power order of some nilpotent-by-nilpotent groups are inner, extending a result by J. Hai and J. Ge, where p is a prime number. 相似文献
30.