全文获取类型
收费全文 | 64000篇 |
免费 | 3212篇 |
国内免费 | 8078篇 |
专业分类
化学 | 52216篇 |
晶体学 | 940篇 |
力学 | 984篇 |
综合类 | 426篇 |
数学 | 10259篇 |
物理学 | 10465篇 |
出版年
2024年 | 70篇 |
2023年 | 503篇 |
2022年 | 1161篇 |
2021年 | 1118篇 |
2020年 | 1442篇 |
2019年 | 1711篇 |
2018年 | 1293篇 |
2017年 | 2045篇 |
2016年 | 1771篇 |
2015年 | 1562篇 |
2014年 | 2254篇 |
2013年 | 5057篇 |
2012年 | 4140篇 |
2011年 | 3257篇 |
2010年 | 2618篇 |
2009年 | 3749篇 |
2008年 | 4014篇 |
2007年 | 4076篇 |
2006年 | 3737篇 |
2005年 | 3332篇 |
2004年 | 3254篇 |
2003年 | 2635篇 |
2002年 | 3333篇 |
2001年 | 2213篇 |
2000年 | 1992篇 |
1999年 | 1939篇 |
1998年 | 1622篇 |
1997年 | 1233篇 |
1996年 | 1035篇 |
1995年 | 1023篇 |
1994年 | 903篇 |
1993年 | 720篇 |
1992年 | 752篇 |
1991年 | 480篇 |
1990年 | 416篇 |
1989年 | 404篇 |
1988年 | 305篇 |
1987年 | 246篇 |
1986年 | 246篇 |
1985年 | 198篇 |
1984年 | 215篇 |
1983年 | 96篇 |
1982年 | 179篇 |
1981年 | 149篇 |
1980年 | 172篇 |
1979年 | 162篇 |
1978年 | 143篇 |
1977年 | 97篇 |
1976年 | 84篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
Magnetic Properties of the Cobaltates Na6CoS4, Na6CoSe4, and K6CoS4 The alkali metal cobalt chalcogenides Na6CoS4, Na6CoSe4, and K6CoS4 crystallize in the space group P63mc with Z = 4. The structure is characterized by isolated [CoX4]-tetrahedra. The magnetic susceptibilities show Curie-Weiss behaviour. The deviations at low temperatures are caused by antiferromagnetic interactions. The magnetic moments are discussed with regard to ligand-field parameters. 相似文献
105.
106.
Kevin Houston 《Inventiones Mathematicae》2002,147(3):471-485
The disentanglement of certain augmentations is shown to be the topological join of a disentanglement and a Milnor fibre.
The kth disentanglement of a finite map is defined and for corank 1 maps from ℂ
n
to ℂ
n
+1 it is shown that they are homotopically equivalent to a wedge of spheres. Applications to the Mond conjecture are given.
Oblatum 24-VII-2000 & 5-VII-2001?Published online: 12 October 2001 相似文献
107.
Robert L. Jerrard Halil Mete Soner 《Calculus of Variations and Partial Differential Equations》2002,14(2):151-191
We study the Ginzburg-Landau functional
for , where U is a bounded, open subset of . We show that if a sequence of functions satisfies , then their Jacobians are precompact in the dual of for every . Moreover, any limiting measure is a sum of point masses. We also characterize the -limit of the functionals , in terms of the function space B2V introduced by the authors in [16,17]: we show that I(u) is finite if and only if , and for is equal to the total variation of the Jacobian measure Ju. When the domain U has dimension greater than two, we prove if then the Jacobians are again precompact in for all , and moreover we show that any limiting measure must be integer multiplicity rectifiable. We also show that the total variation
of the Jacobian measure is a lower bound for the limit of the Ginzburg-Landau functional.
Received: 15 December 2000 / Accepted: 23 January 2001 / Published online: 25 June 2001 相似文献
108.
R. Gerbaldo G. Ghigo G. Giunchi L. Gozzelino F. Laviano E. Mezzetti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):297-300
We present results from an extended magneto-optical (MO) analysis of two samples cut from high-density pellets of MgB2. The first sample was studied in order to show that no matter how large the sample is and despite the bulk granularity, the
material enters into a critical state in a crystal-like fashion. The second sample was chosen for the quantitative analysis.
A numerical approach based on an inverted 2D Biot-Savart model was used to calculate the current paths across the homogeneous
polycrystalline bulk, as well as in the vicinity and across some morphological defects. Local current densities in the homogeneous
part were estimated as a function of the applied magnetic field at different temperatures, in three regimes: below full penetration,
at full penetration and above full penetration, respectively. A hypothesis of interpretation of the apparent absence of magnetic
granularity inside the polycrystalline microstructure is presented. It is related to a critical state likely reached by a
network of strongly coupled Josephson junctions.
Received 31 May 2001 and Received in final form 5 December 2001 相似文献
109.
Several α-ketoalcohols of synthetic value were resolved using lipase as a catalyst. Lipoprotein lipase (LPL) provided the best rate of hydrolysis and kinetic differentiation. One of these optically pure α-ketoalcohol was converted to (5)-ibuprofen in good optical purity. The stereospecific inversion of (R)-alcohol to (S)-alcohol is described. 相似文献
110.
许多乙酰芳胺类化合物具有优异的生物活性,例如除草剂苯噻草胺,可抑制细胞生长和分裂,防除稻田中禾本科杂草[1];杀菌剂甲霜灵可防治作物霜霉病[2]。本文将具有多种生物活性的嘧啶基团引入到乙酰芳胺结构中[3],合成下列10个未见文献报道的标题化合物Ⅰ,通... 相似文献