全文获取类型
收费全文 | 764篇 |
免费 | 41篇 |
国内免费 | 3篇 |
专业分类
化学 | 518篇 |
晶体学 | 5篇 |
力学 | 17篇 |
数学 | 142篇 |
物理学 | 126篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 27篇 |
2019年 | 29篇 |
2018年 | 22篇 |
2017年 | 8篇 |
2016年 | 30篇 |
2015年 | 24篇 |
2014年 | 25篇 |
2013年 | 39篇 |
2012年 | 43篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 33篇 |
2007年 | 18篇 |
2006年 | 25篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 24篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1987年 | 4篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1969年 | 7篇 |
1944年 | 6篇 |
1943年 | 7篇 |
1910年 | 5篇 |
排序方式: 共有808条查询结果,搜索用时 296 毫秒
161.
Sergio Albeverio Jens-Erik Fenstad Raphael Høegh-Krohn Witold Karwowski Tom Lindstrøm 《Physics letters. A》1984,104(8):396-400
We discuss hamiltonians in L2(Rd, dx) of the form H = ?Δ + V, with V a potential supported by a zero measure set C. In particular if C is a path of a brownian motion b such that V(x) = ∫01λ(x, ω)δ(x-b(s, ω)) ds, we show that H exists as a nontrivial, self-adjoint, lower bounded perturbation of ?Δ when d ?5. We must choose λ to be an infinitesimal, negative function for d = 4,5, but for d ? 3 any bounded real-valued function λ will do. The connection with Edward's model of polymers as well as with quantum fields of the ?d4-type is also discussed. The proofs use methods of nonstandard analysis. 相似文献
162.
Raphael BeumerPau Bayón Piergiuliano BugadaSylvie Ducki Nicola MongelliFederico Riccardi Sirtori Joachim Telser Cesare Gennari 《Tetrahedron letters》2003,44(4):681-684
The synthesis of a number of novel simplified eleutheside analogues with potent tubulin-assembling and microtubule-stabilizing properties is described, using ring-closing metathesis as the key-step for obtaining the 6-10 fused bicyclic ring system. 相似文献
163.
Applied Biochemistry and Biotechnology - 相似文献
164.
The hypothesis that relative humidity (RH) of air exerts an effect on voice has been widely accepted. The aim of this study has been to assess whether this can be demonstrated. Eight healthy subjects inhaled during ten minutes three different air conditions: dry, standard room, and humidified air. After inhalation, the subjects produced repeatedly a sustained /a/ of controlled pitch and loudness, which was analyzed for perturbation and noise-to-harmonic parameters. Perturbation measures increased after inhalation of dry air. No significant differences existed between standard and humidified air. No significant difference in the noise-to-harmonic ratio was found among the three conditions. We conclude that the human voice is very sensitive to decreases in RH of inhaled air, because even after a short provocation with dry air, a significant increase in perturbation measures was found. 相似文献
165.
Spencer Knapp Karen E. Rodriques Anthony T. Levorse Raphael M. Ornaf 《Tetrahedron letters》1985,26(15):1803-1806
Treatment of an unsaturated amide with TMS-OTf, then iodine in THF gives the iodolactam. 相似文献
166.
The first elaboration of the novel framework of the alliacane group of sesquiterpene lactones is exemplified by the synthesis of (±)-8,9-deoxyalliacol B (13). 相似文献
167.
Box-spline–based approach to the formulation of numerical methods for partial differential equations
Harvey Diamond Louise Arakelian Raphael Daniel A. Williams 《Numerical Methods for Partial Differential Equations》1992,8(3):291-301
A multivariate box spline framework for the formulation of numerical methods for partial differential equations has been constructed. In particular, a fourth-order Galerkin method and a second-order collocation method were derived and applied to a test problem (classical Poisson equation on a square). The examples indicate that accuracy compares favorably with standard methods and the success of iterative schemes suggests an underlying stabilizing effect. 相似文献
168.
A new route, readily applicable on a large scale, is described to the phenanthrene () the key intermediate in the synthesis of steganone (). 相似文献
169.
Sergio Albeverio Raphael Høegh-Krohn Boguslav Zegarlinski 《Communications in Mathematical Physics》1989,121(4):683-697
We consider quantum fields with weak coupling in two space-time dimensions. We prove that the set of their ultraregular Gibbs states consists of only one point and this point is an extremal Gibbs state. 相似文献
170.
Raphael I. Benhamou Maayan Bibi Prof. Judith Berman Prof. Micha Fridman 《Angewandte Chemie (International ed. in English)》2018,57(21):6230-6235
A critical aspect of drug design is optimal target inhibition by specifically delivering the drug molecule not only to the target tissue or cell but also to its therapeutically active site within the cell. This study demonstrates, as a proof of principle, that drug efficacy can be increased considerably by a structural modification that targets it to the relevant organelle. Specifically, by varying the fluorescent dye segment an antifungal azole was directed from the fungal cell mitochondria to the endoplasmic reticulum (ER), the organelle that harbors the drug target. The ER‐localized azole displayed up to two orders of magnitude improved antifungal activity and also dramatically reduced the growth of drug‐tolerant fungal subpopulations in a panel of Candida species, which are the most prevalent causes of serious human fungal infections. The principle underlying the “target organelle localization” approach provides a new paradigm to improve drug potency and replenish the limited pipeline of antifungal drugs. 相似文献