全文获取类型
收费全文 | 2636篇 |
免费 | 112篇 |
国内免费 | 11篇 |
专业分类
化学 | 1785篇 |
晶体学 | 14篇 |
力学 | 88篇 |
数学 | 380篇 |
物理学 | 492篇 |
出版年
2023年 | 21篇 |
2022年 | 54篇 |
2021年 | 56篇 |
2020年 | 63篇 |
2019年 | 73篇 |
2018年 | 56篇 |
2017年 | 39篇 |
2016年 | 107篇 |
2015年 | 78篇 |
2014年 | 89篇 |
2013年 | 163篇 |
2012年 | 184篇 |
2011年 | 190篇 |
2010年 | 125篇 |
2009年 | 101篇 |
2008年 | 163篇 |
2007年 | 151篇 |
2006年 | 124篇 |
2005年 | 113篇 |
2004年 | 116篇 |
2003年 | 80篇 |
2002年 | 95篇 |
2001年 | 43篇 |
2000年 | 40篇 |
1999年 | 22篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 8篇 |
1989年 | 17篇 |
1988年 | 8篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 20篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1957年 | 23篇 |
排序方式: 共有2759条查询结果,搜索用时 15 毫秒
891.
I. Bang J. A. Mandel H. Steudel O. Folin L. Pincussen F. Fregl F. Emich H. Lieb J. V. Dubsky A. Fodor J. Herzog W. Denis R. D. Bell L. Hannaert R. Wodon C. Vallée A. Polonowski P. E. Howe E. L. Kennaway K. L. Gad-Andresen R. Fosse M. Nicloux G. Welter 《Analytical and bioanalytical chemistry》1923,63(1-2):72-80
892.
K. Petri 《Mathematische Annalen》1923,88(3-4):242-289
Ohne Zusammenfassung 相似文献
893.
Lionello Petri 《Colloid and polymer science》1926,39(1):63-67
Ohne Zusammenfassung 相似文献
894.
P. Drescher H. G. Andresen K. Aulenbacher J. Bermuth Th. Dombol H. Fischerz H. Euteneuer N. N. Faleev M. S. Galaktionov D. v. Harrach P. Hartmann J. Hoffmann P. Jennewein K. H. Kaiser S. Köbis O. V. Kovalenkov H. J. Kreide J. Langbeine Y. A. Mamaev Ch. Nachtigall M. Petri S. Plützer E. Reicherte M. Schemies H. -J. Schöpe K. -H. Steffens M. Steigerwald A. V. Subashiev H. Trautner D. A. Vinokurov Y. P. Yashin B. S. Yavich 《Applied Physics A: Materials Science & Processing》1996,63(2):203-206
Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10–3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully. 相似文献
895.
Summary In this paper we present a numerical study of the SFUR (self-filtering unstable resonator) cavity resonant modes and numerical
results are compared with the experimental data. The numerical code developed for analysing the SFUR cavity will also allow
for studying a wider class of resonators, and is therefore a very useful tool in designing new laser cavities. 相似文献
896.
Denis A. W. White 《Letters in Mathematical Physics》1986,11(2):121-126
Scattering of a quantum mechanical particle by a long-range potential is studied using Enss's time-dependent method. More precisely, a simple and natural extension of the Enss method to a two Hilbert space setting is established. Applied to the consideration of long-range scattering, this extended Enss method reduces the problem of proving existence and completeness of the wave operators to the problem of solving an eikonal equation on a cone in phase space. Relying on a solution of the eikonal equation constructed by Isozaki and Kitada, it is shown that the wave operators exist and are complete whenever the potential is in the long-range class introduced by Hörmander. 相似文献
897.
A solution of the solar neutrino problem based on certain differences between T(opological) G(eometro) D(ynamics) and the standard model of the electroweak interactions is proposed. First, TGD predicts the existence of a right-handed neutrino inert with respect to ordinary electroweak interactions. Second, the generalization of the massless Dirac equation contains terms mixing differentM
4 chiralities, unlike the ordinary massless Dirac equation. This and the observation of anticorrelations of the solar neutrino flux with sunspot number suggest that solar neutrinos are transformed to right-handed neutrinos on the convective zone of the Sun. Third, the compactness ofCP
2 implies topological field quantization: space-time decomposes into regions, topological field quanta, characterized by a handful of vacuum quantum numbers. In particular, there are topological obstructions for the smooth global imbeddings of magnetic fields and the decomposition of the solar magnetic field into flux tubes is predicted. Finally, every electromagnetically neutral mass distribution is accompanied by a long-rangeZ
0 vacuum field. If the vacuum quantum numbers inside the flux tubes of the solar magnetic field are considerably smaller than in the normal phase, theZ
0 electric force becomes strong and implies Thomas precession for the spin of the lefthanded component of the neutrino. As a consequence, left-handed neutrinos are transformed to right-handed ones and the process is irreversible, since righthanded neutrinos do not couple toZ
0. 相似文献
898.
899.
Daoning Su Ian Norris Chris Peters Denis R. Hall Julian D.C. Jones 《Optics and Lasers in Engineering》1993,18(5):371-376
Progress in laser material processing may require real-time monitoring and process control for consistent quality and productivity. We report a method of in-situ monitoring of laser metal cutting and drilling using cladding power monitoring of an optical fibre beam delivery system—a technique which detects the light reflected or scattered from the workpiece. The light signal carries information about the quality of the process. Experiments involving drilling and cutting of two samples, a thin aluminum foil and a 2-mm thick stainless steel plate, confirmed the effectiveness of this method. 相似文献
900.
We study the group of dressing transformations in soliton theories. We show that it is generated by the monodromy matrix. This provides a new proof of their Lie-Poisson property. We treat in detail the examples of the Toda field theories and the Heisenberg model. We show that the group of dressing transformations is the classical precursor of the various manifestations of quantum groups in these models, e.g. algebraic Bethe ansatz, non-local currents, or quantum group symmetries. Finally, we define field multiplets supporting a linear representation of the dressing group and we show that their exchange algebras are encoded in the classical double.Communicated by K. Gawedzki 相似文献