全文获取类型
收费全文 | 743篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
化学 | 488篇 |
晶体学 | 3篇 |
力学 | 15篇 |
数学 | 56篇 |
物理学 | 207篇 |
出版年
2021年 | 10篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 19篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 43篇 |
2012年 | 31篇 |
2011年 | 34篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 26篇 |
2007年 | 19篇 |
2006年 | 30篇 |
2005年 | 31篇 |
2004年 | 18篇 |
2003年 | 20篇 |
2002年 | 32篇 |
2001年 | 11篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1972年 | 8篇 |
1971年 | 5篇 |
1970年 | 8篇 |
1967年 | 6篇 |
排序方式: 共有769条查询结果,搜索用时 15 毫秒
91.
Meade Bolton C. Kraus T. Leone Link Heraeus Flügge A. Pfeiffer E. Esmarch Carl Fränkel von Sehlen's M. Hochstetter G. Bischof Alex Köbrich O. Kasper Dupré Joseph Klein John Henry Smith J. W. Mallet's E. Reichardt Mayrhofer Leopold Spiegel Katharine J. Williams W. Ramsay A. B. Cooper Baeseler Nobbe Will W. Knop C. W. Heaton Thomas Stevenson Odling Tidy Crookes P. T. Austen Austen Francis A. Wilber 《Analytical and bioanalytical chemistry》1888,27(1):77-84
92.
The rearrangement of 2-amino-5-phenacyloxazoles with dimethylamine is described. One such rearrangement provided an unexpected tricyclic product. 相似文献
93.
A.A. Bichl J.M. Grimstrup H. Grosse E. Kraus L. Popp M. Schweda R. Wulkenhaar 《The European Physical Journal C - Particles and Fields》2002,24(1):165-176
We show that the non-commutative Yang–Mills field forms an irreducible representation of the (undeformed) Lie algebra of
rigid translations, rotations and dilatations. The non-commutative Yang–Mills action is invariant under combined conformal
transformations of the Yang–Mills field and of the non-commutativity parameter . The Seiberg–Witten differential equation results from a covariant splitting of the combined conformal transformations and
can be computed as the missing piece to complete a covariant conformal transformation to an invariance of the action.
Received: 6 November 2001 / Published online: 5 April 2002 相似文献
94.
Kraus RM Lagoudakis PG Rogach AL Talapin DV Weller H Lupton JM Feldmann J 《Physical review letters》2007,98(1):017401
The excited state of colloidal nanoheterostructures consisting of a spherical CdSe nanocrystal with an epitaxially attached CdS rod can be perturbed effectively by electric fields. Field-induced fluorescence quenching coincides with a conversion of the excited state species from the bright exciton to a metastable trapped state (dark exciton) characterized by a power-law luminescence decay. The conversion is reversible so that up to 10% of quenched excitons recombine radiatively post turn-off of a 1 micro s field pulse, increasing the delayed luminescence by a factor of 80. Excitons can be stored for up to 10(5) times the natural lifetime, opening up applications in optical memory elements. 相似文献
95.
Levels of recrystallization have been measured by two distinct techniques; a splat cooling assay and a new device, an optical recrystallometer, which measures the change in light transmittance through a frozen sample. Both techniques indicate the presence of recrystallization inhibitors in a grass extract and in other samples. The advantages of each method of measuring recrystallization are discussed. 相似文献
96.
97.
In the present work a hierarchical multiscale approach, based on finite element method, is applied in order to characterize the heat affected zone (HAZ) of a welded joint with parent material S460M. The metallurgical constituents of particular regions of the HAZ was determined experimentally and, regarding the multiscale approach, a first-order computational homogenization method was implemented. In this context, effective stress-strain-relations in particular spots of the HAZ are determined applying prescribed displacement boundary conditions. The obtained relations were considered in subsequent finite element calculations of butt-welded joints under tensile loading, allowing a comparison of the numerical strain states to experimental results. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
98.
Johann Lacava Anika Weber Tobias Kraus 《Particle & Particle Systems Characterization》2015,32(4):458-466
The ageing of spherical gold nanoparticles having 6‐nm‐diameter cores and a ligand shell of dodecanethiol is investigated under different storage conditions. Losses caused by agglomeration and changes in optical particle properties are quantified. Changes in colloidal stability are probed by analytical centrifugation in a polar solvent mixture. Chemical changes are detected by elementary analysis of particles and solvent. Fractionation occurs under all storage conditions. Ageing is not uniform but broadens the property distributions of the particles. Small‐number statistics in the ligand shell density and the morphological heterogeneity of particles are possible explanations. Washing steps exacerbate ageing, a process that could not be fully reversed by excess ligands. Dry storage is not preferable to storage in solvent. Storage under inert argon atmosphere reduces losses more than all other conditions but could not prevent it entirely. 相似文献
99.
We present the low‐temperature synthesis of potassium hexaamido zirconate(IV) from the transition metal tetrafluoride and thealkali metal dissolved in liquid ammonia at –40 °C. Potassium hexaamido zirconate(IV) K2[Zr(NH2)6] is the first ternary amide reported for elements of group 4 of the periodic table It crystallizes with a novel structure type in the trigonal space group R$\bar{3}$ c with a = 6.5422(2) Å, c = 32.824(2) Å, V = 1216.66(9) Å3, Z = 6 and c/a = 5.017. The structure can be derived from the K2PtCl6 type. The compound contains discrete D3‐symmetric [Zr(NH2)6]2– anions which differ significantly from octahedral shape. Quantum chemical calculations show the distortion to arise from a splitting of degenerate d‐orbitals on the zirconium atom leading to a significant gain in energy. 相似文献
100.