全文获取类型
收费全文 | 673篇 |
免费 | 21篇 |
国内免费 | 21篇 |
专业分类
化学 | 409篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 167篇 |
物理学 | 127篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 23篇 |
2015年 | 21篇 |
2014年 | 25篇 |
2013年 | 35篇 |
2012年 | 46篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 31篇 |
2008年 | 51篇 |
2007年 | 55篇 |
2006年 | 57篇 |
2005年 | 39篇 |
2004年 | 42篇 |
2003年 | 29篇 |
2002年 | 32篇 |
2001年 | 8篇 |
2000年 | 1篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1914年 | 1篇 |
排序方式: 共有715条查询结果,搜索用时 15 毫秒
61.
Greg Hughes Paul O'Shea Julie Goll Danny Gauvreau Jennifer Steele 《Tetrahedron》2009,65(16):3189-5650
Effective protocols for the introduction of chiral α-trifluoromethyl benzyl moieties by nucleophilic displacement of enantiomerically enriched α-trifluoromethyl benzylic triflates are presented. The effects of substrate electronics, solvent polarity, temperature, and base are studied by measuring the diastereomeric or enantiomeric excesses of the displacement products formed by coupling a variety of α-trifluoromethyl benzylic triflates with a range of nucleophiles including amines, carboxylates, thiols, and malonates. Preliminary investigations to elucidate the mechanism(s) involved in the loss of stereochemical integrity at the benzylic center in the nucleophilic displacement reactions are also reported. 相似文献
62.
Schabas G Wang CW Oskooei A Yusuf H Moffitt MG Sinton D 《Langmuir : the ACS journal of surfaces and colloids》2008,24(19):10596-10603
The controlled self-assembly of polymer-stabilized quantum dots (QDs) into mesoscale aqueous spherical assemblies termed quantum dot compound micelles (QDCMs) using a two-phase gas-segmented microfluidic reactor is described. Self-assembly is initiated by the fast mixing of water (approximately 1 s) with a blend solution of polystyrene-coated QDs and amphiphilic polystyrene-block-poly(acrylic acid) stabilizing chains via chaotic advection within liquid plugs moving through a sinusoidal channel. Subsequent recirculating flow within a post-formation channel subjects the dynamic QDCMs to shear-induced processing, controlled via the flow rate and channel length, before a final quench into pure water. During processing, larger QDCMs within the initial population undergo breakup into smaller particles, resulting in smaller mean particle sizes, smaller relative standard deviations, and more skewed distribution shapes, as the overall shear exposure is increased. For these cases, shear-induced size reduction is sufficient to dominate surface tension-driven growth. 相似文献
63.
64.
Brewer C Brewer G Butcher RJ Carpenter EE Cuenca L Schmiedekamp AM Viragh C 《Dalton transactions (Cambridge, England : 2003)》2005,(22):3617-3619
The iron(II) and manganese(II) complexes of the N(7) Schiff-base condensate of tris(3-aminopropyl)amine with 1-methyl-2-imidazolecarbaldehyde and the manganese(II) complex of the N(7) Schiff-base condensate of tris(3-aminopropyl)amine with 4-imidazolecarbaldehyde are high-spin mono capped octahedral seven-coordinate complexes with a short, approximately 2.44 è, metal to apical nitrogen bond. 相似文献
65.
Non-treeability for product group actions 总被引:1,自引:0,他引:1
Greg Hjorth 《Israel Journal of Mathematics》2008,163(1):383-409
A product of two lcsc non-compact groups G
1 × G
2 acting freely by measure preserving transformation on a standard Borel probability space gives rise to a non-treeable equivalence
relation unless both groups are amenable.
Partially supported by NSF grant DMS 0140503 相似文献
66.
67.
Greg BG Moorhead Laura Trinkle-Mulcahy Mhairi Nimick Veerle De Wever David G Campbell Robert Gourlay Yun Wah Lam Angus I Lamond 《BMC biochemistry》2008,9(1):28
Background
Protein phosphatase one (PP1) is a ubiquitously expressed, highly conserved protein phosphatase that dephosphorylates target protein serine and threonine residues. PP1 is localized to its site of action by interacting with targeting or regulatory proteins, a majority of which contains a primary docking site referred to as the RVXF/W motif. 相似文献68.
We consider random Hermitian matrices in which distant above‐diagonal entries are independent but nearby entries may be correlated. We find the limit of the empirical distribution of eigenvalues by combinatorial methods. We also prove that the limit has an algebraic Stieltjes transform by an argument based on dimension theory of Noetherian local rings. © 2008 Wiley Periodicals, Inc. 相似文献
69.
Massoud Kaykhaii Greg W. Dicinoski Rebecca Smedley Janusz Pawliszyn Paul R. Haddad 《Journal of chromatography. A》2010,1217(20):3452-3456
The use of a functionalized latex nanoparticle coating as a new sorbent phase for solid-phase microextraction (SPME) was examined. By means of electrostatic absorption onto ionized silanol groups, a fused-silica rod was coated with polymeric nanoparticles functionalized with quaternary ammonium groups. Optimum conditions for the preparation of the coated fibre are presented. The fibre was used for the extraction of a mixture of seven anions from water samples which are analysed by coupling the SPME fibre to an ion chromatographic system via a special interface. The results obtained proved the suitability of this novel coating as a new SPME fibre. A linear calibration for the target analytes was achieved over the concentration range from 5 μg L−1 to 5 mg L−1 (r2 > 0.988), while limits of detection for these ions were all below 3.7 μg L−1 (S/N = 3). The reproducibility of a single fibre (n = 4) under similar conditions was between 7 and 12%, while the fibre to fibre reproducibility (n = 5) was between 8.9 and 14%. 相似文献
70.
This article treats Nevanlinna–Pick interpolation in the setting of a special class of algebraic curves called distinguished varieties. An interpolation theorem, along with additional operator theoretic results, is given using a family of reproducing kernels naturally associated to the variety. The examples of the Neil parabola and doubly connected domains are discussed. 相似文献