全文获取类型
收费全文 | 372篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 226篇 |
晶体学 | 4篇 |
力学 | 24篇 |
数学 | 39篇 |
物理学 | 86篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 19篇 |
2007年 | 14篇 |
2006年 | 20篇 |
2005年 | 16篇 |
2004年 | 13篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1987年 | 4篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1913年 | 2篇 |
1912年 | 2篇 |
1890年 | 2篇 |
1889年 | 1篇 |
排序方式: 共有379条查询结果,搜索用时 796 毫秒
91.
Maria Antonia Iat Rosalba Saija Arianna Giusto Paolo Denti Ferdinando Borghese Cesare Cecchi-Pestellini 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,100(1-3):157-164
We calculate the energy density distribution in the ultraviolet within small spheres containing concentric cavities, aimed at simulating interstellar dust grains. We explore the dependence on chemical composition by progressively changing, in an arbitrary way, the refractive index of the sphere material. We conclude that a significant fraction of the energy of the impinging radiation is trapped throughout the particle interior. 相似文献
92.
L.S. Campana A. Caramico DAuria M. DAmbrosio L. De Cesare U. Esposito 《Physica A》1984,123(1):279-295
The paper is devoted to an investigation of the damping effects of the Fermion elementary excitations in the Jordan-Wigner representation of a one-dimensional anisotropic model in an external field. This is realized on the basis of the “Gaussian ansatz”, recently proposed by Nolting and Oles, as substituting the standard “polar ansatz” in the Spectral Density Method, for exploring damping effects of quasi-particles in many-body problems. By using a first order approximation, we are able to obtain reasonable results in the low temperature limit. 相似文献
93.
Mariateresa Giustiniano Sveva Pelliccia Ettore Novellino Gian Cesare Tron 《Tetrahedron letters》2018,59(13):1196-1199
N-Substituted α-amino acid amides can be easily obtained in two steps using the four-component Ugi reaction followed by chemoselective cleavage of the resulting tertiary amide. The use of the sacrificial acid, 2-hydroxymethylbenzoic acid is associated to shorter reaction times, higher yields, and safer and greener reaction conditions compared to strategies based on trifluoroacetic acid, a toxic and environmental hazardous reagent. The optimized procedure was easily scaled up to gram amounts. 相似文献
94.
Philippe Remuzon Daniel Bouzard Pierre Di Cesare Christian Dussy Jean-Pierre Jacquet Alexandre Jaegly 《Journal of heterocyclic chemistry》1992,29(4):985-989
The 5-hydroxymethyl and the 5-formyl-1-cyclopropyl-6-fluoro-7-piperazinyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids have been prepared via a 5-trimethylsilyl group and were tested in vitro as potential antibacterials. 相似文献
95.
Cesare Oliva Marco Scavini Agusti Sin Yuri Dubitsky 《Journal of solid state chemistry》2004,177(11):4104-4111
EPR analysis is carried out with Ce1−xGdxO(4−x)/2 (x=0.1; 0.2) nanopowders aiming at obtaining information about their oxidation and reduction properties. The EPR spectrum of these systems is composed of a single feature. The first derivative peak-to-peak spectral intensity decreases at higher temperatures, but this trend deviates from that of Curie's law with the x=0.1 sample, at difference with the x=0.2 sample. This unexpected result is related to oxygen deficiency, due to gas-solid equilibrium, present in the former sample only. As a consequence, some Ce3+ ions would form providing it with conduction electrons propagating as small polarons in a percolative way. This would result in a thinner skin depth at higher temperatures, able to explain the deviation of the spectral intensity from its expected value. Indeed, this deviation from Curie's law is reduced or disappears at all after thermal treatment of the x=0.1 sample with O2. 相似文献
96.
The occurrence of non-abelian anomalies in gauge theories and gravitation, first discovered via perturbative techniques, is now completely explained from the mathematical point of view by means of the family index theorem of Atiyah and Singer. Here we make contact between this approach and BRS cohomology, by showing that they yield the same non-abelian anomalies, provided a certain restriction to local functionals is not introduced from the very beginning. In particular, this solves the unicity problem for this kind of anomalies. Local BRS cohomology is still relevant for the abelian case.Work partially supported by Gruppo Nazionale di Fisica Matematica del CNR and Progetto Nazionale Geometria e Fisica del MPI 相似文献
97.
98.
The Rh-catalyzed hydrogenations of dimethyl itaconate and methyl acetamido acrylate using selected heterocombinations of pentafluorobenzyl- and methoxybenzyl-derived binaphthyl phosphites proved to be highly enantioselective (ee 93-99%). In these selected cases the Rh-heterocomplexes, which were formed in a statistical amount (ca. 50% by 31P NMR), turned out to be more active and selective than the two homocomplexes. 相似文献
99.
100.
Nematodynamics is the orientation dynamics of flowless liquid-crystals. We show how Euler-Poincaré reduction produces a unifying framework for various theories, including Ericksen-Leslie, Luhiller-Rey, and Eringen??s micropolar theory. In particular, we show that these theories are all compatible with each other and some of them allow for more general configurations involving a non vanishing disclination density. All results are also extended to flowing liquid crystals. 相似文献