全文获取类型
收费全文 | 1066篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 559篇 |
晶体学 | 2篇 |
力学 | 41篇 |
数学 | 85篇 |
物理学 | 395篇 |
出版年
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 50篇 |
2012年 | 35篇 |
2011年 | 60篇 |
2010年 | 33篇 |
2009年 | 21篇 |
2008年 | 53篇 |
2007年 | 48篇 |
2006年 | 46篇 |
2005年 | 47篇 |
2004年 | 52篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 27篇 |
2000年 | 34篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 12篇 |
1995年 | 16篇 |
1994年 | 22篇 |
1993年 | 31篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1975年 | 8篇 |
1974年 | 12篇 |
1973年 | 16篇 |
1972年 | 7篇 |
1968年 | 7篇 |
排序方式: 共有1082条查询结果,搜索用时 15 毫秒
71.
Ingvar Johansson 《Metaphysica》2012,13(1):87-105
The paper claims that Hume??s philosophy contains an ontology, i.e. an abstract exhaustive classification of what there is. It is argued that Hume believes in the existence of a mind-independent world, and that he has a classification of mind-related entities that contains four top genera: perception, faculty, principle and relation. His ontology is meant to be in conformity with his philosophy of language and epistemology, and vice versa. Therefore, crucial to Hume??s ontology of mind-independent entities is his notion of ??supposing relative ideas??. Entities that are referred to by means of ordinary ideas can be truly classified, whereas entities that are referred to by means of relative ideas can only be hinted at. When Hume??s ontology is highlighted and systematised, his notion ??the faculty of imagination?? becomes highly problematic. However, the exposition also makes it clear that Hume deserves the honorary title: the first cognitive scientist. 相似文献
72.
We use density-functional perturbation theory to obtain the phonon spectrum of fcc xenon under pressure. Thermodynamic properties obtained within the quasiharmonic approximation are in fair to good agreement with experiment at zero pressure. The transition pressure from the fcc to hcp phase is predicted to occur at 5 GPa. The fcc structure is found to be dynamically stable up to a pressure of 100 GPa, beyond which the phonon modes at the X and L symmetry points soften. We attribute the observed sluggish kinetics of the fcc-hcp transition to the small energy difference between the phases as well as to the high dynamical stability of the fcc phase. 相似文献
73.
Skorodumova NV Simak SI Lundqvist BI Abrikosov IA Johansson B 《Physical review letters》2002,89(16):166601
The microscopic mechanism behind the extraordinary ability of ceria to store, release, and transport oxygen is explained on the basis of first-principles quantum mechanical simulations. The oxygen-vacancy formation energy in ceria is calculated for different local environments. The reversible CeO2-Ce2O3 reduction transition associated with oxygen-vacancy formation and migration is shown to be directly coupled with the quantum process of electron localization. 相似文献
74.
Brodowski W Bilger R Calén H Clement H Ekström C Fransson K Greiff J Häggström S Höistad B Johanson J Johansson A Johansson T Kilian K Kullander S Kupść A Marciniewski P Morosov B Oelert W Pätzold J Ruber RJ Schepkin M Scobel W Seluzhenkov I Stepaniak J Sukhanov A Turowiecki A Wagner GJ Wilhelmi Z Zabierowski J Zlomanczuk J 《Physical review letters》2002,88(19):192301
The pp-->pp pi(+) pi(-) reaction has been measured exclusively near threshold at CELSIUS. The total cross sections are nearly an order of magnitude lower than expected from previous inclusive measurements. The differential cross sections reveal pp-->pp(*)(1440)-->pp sigma = pp(pi(+)pi(-))(I = l = 0) as the dominant process as well as significant contributions from p(*)-->Delta(++)pi(-)-->psigma. The observed anisotropy in the proton angular dependence is consistent with heavy-meson exchange. In the invariant mass spectra, no narrow structures of statistical relevance (3sigma) are found. 相似文献
75.
On the distribution of the length of the longest increasing subsequence of random permutations 总被引:18,自引:0,他引:18
Jinho Baik Percy Deift Kurt Johansson 《Journal of the American Mathematical Society》1999,12(4):1119-1178
The authors consider the length, , of the longest increasing subsequence of a random permutation of numbers. The main result in this paper is a proof that the distribution function for , suitably centered and scaled, converges to the Tracy-Widom distribution of the largest eigenvalue of a random GUE matrix. The authors also prove convergence of moments. The proof is based on the steepest descent method for Riemann-Hilbert problems, introduced by Deift and Zhou in 1993 in the context of integrable systems. The applicability of the Riemann-Hilbert technique depends, in turn, on the determinantal formula of Gessel for the Poissonization of the distribution function of .
76.
Johan Samuelsson Mats Jonsson Tore Brinck Mats Johansson 《Journal of polymer science. Part A, Polymer chemistry》2004,42(24):6346-6352
The reactivities and reaction rates of the thiol–ene coupling reaction of 2‐ethyl‐(hydroxymethyl)‐1,3‐propanediol trimercapto acetate and 2‐ethyl‐(hydroxymethyl)‐1,3‐propanediol trimercapto propionate with two common unsaturated fatty acid methyl esters (methyl oleate and methyl linoleate) were evaluated. The reactions were monitored with real‐time IR and 1H NMR, which both showed that the mercapto acetate was more reactive than the mercapto propionate. Both thiols were more prone to add to the monounsaturated methyl oleate than to methyl linoleate, which contained two unconjugated double bonds. According to bond energy calculations, the thiol hydrogen of mercapto acetate was somewhat more difficult to abstract than the hydrogen of mercapto propionate. Consequently, the formed S? C bond in the acetate case was stronger than in the propionate case, and so the equilibrium was more shifted toward the addition products. The real‐time IR measurements also showed that the cis unsaturation in methyl oleate isomerized much more quickly than that in methyl linoleate, and this also had an impact on the overall addition rate of the thiols because a trans unsaturation was more reactive than a cis unsaturation. The higher isomerization rates in the oleate systems, compared with those of the linoleate systems, was suggested to be due to a more restricted rotation along the C? C bond of the reacted unsaturation in linoleate. This study showed the importance of trans unsaturations in obtaining reasonable reaction rates in thiol–ene reactions with fatty acid derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6346–6352, 2004 相似文献
77.
78.
Core level binding energy shifts for the element A of a large number of dilute alloys AB have been measured, where the concentration of the dilute component A is 10% or less. The experimental shifts are analysed in terms of alloy heat of formation data, for which we have used Miedema's semi-empirical scheme. Good overall agreement is obtained between the experimental data and the calculated values, encouraging the use of electron spectroscopy for evaluating solution energies of metallic systems. 相似文献
79.
80.
The temperature dependence of the magnetic hyperfine fields at the sites of F nuclei implanted into ferromagnetic Fe, Ni and Gd has been studied in the temperature range from 77 K to 670 K. A pulsed proton beam was used to observe the time-differential precession of the 5/2+ state in19F. Deviations from the bulk magnetization were found for Fe and Ni. The damping of the two observed fields in Ni was interpreted in terms of a field distribution caused by an induced radiation damage. The occupation sites for F and possible mechanisms of the anomalous temperature dependence are discussed. 相似文献