全文获取类型
收费全文 | 4876篇 |
免费 | 74篇 |
国内免费 | 11篇 |
专业分类
化学 | 2793篇 |
晶体学 | 9篇 |
力学 | 56篇 |
综合类 | 1篇 |
数学 | 505篇 |
物理学 | 1597篇 |
出版年
2020年 | 51篇 |
2019年 | 35篇 |
2018年 | 38篇 |
2016年 | 55篇 |
2015年 | 53篇 |
2014年 | 61篇 |
2013年 | 98篇 |
2012年 | 120篇 |
2011年 | 159篇 |
2010年 | 101篇 |
2009年 | 75篇 |
2008年 | 138篇 |
2007年 | 172篇 |
2006年 | 166篇 |
2005年 | 155篇 |
2004年 | 150篇 |
2003年 | 133篇 |
2002年 | 115篇 |
2001年 | 114篇 |
2000年 | 91篇 |
1999年 | 84篇 |
1998年 | 72篇 |
1997年 | 67篇 |
1996年 | 85篇 |
1995年 | 89篇 |
1994年 | 97篇 |
1993年 | 93篇 |
1992年 | 110篇 |
1991年 | 73篇 |
1990年 | 60篇 |
1989年 | 53篇 |
1988年 | 66篇 |
1987年 | 68篇 |
1986年 | 61篇 |
1985年 | 64篇 |
1984年 | 60篇 |
1983年 | 48篇 |
1982年 | 68篇 |
1981年 | 57篇 |
1980年 | 51篇 |
1979年 | 52篇 |
1978年 | 53篇 |
1977年 | 50篇 |
1976年 | 42篇 |
1975年 | 47篇 |
1974年 | 45篇 |
1973年 | 62篇 |
1972年 | 31篇 |
1971年 | 40篇 |
1956年 | 31篇 |
排序方式: 共有4961条查询结果,搜索用时 0 毫秒
11.
12.
F. Seiffert R. Schwengner G. Winter L. Funke W. Lieberz R. Reinhardt K. P. Schmittgen D. Weil R. Wrzal K. O. Zell P. von Brentano 《Zeitschrift für Physik A Hadrons and Nuclei》1991,340(2):141-153
Excited states of73Se have been investigated up to spin, 21/2 using techniques of in-beamγ-ray spectroscopy in connection with the70Ge(α, n) reaction. Mean lifetimes of 12 levels have been determined applying Doppler-shift andγ-RF-methods. Five different bands have been identified that reflect a variety of different excitation modes. The decoupled 9/2+ band is likely to correspond to an oblate deformation while the 5/2+ band is interpreted as a strongly coupled prolate band built on the Nilsson configuration [422] 5/2+. The 3/2? band is a strongly coupled band built on the [301] 3/2} configuration.Nuclear reactions:70Ge(α,n),E=14, 16, 18, 19, 20MeV; measuredE γ,I γ,σ(E γ,θ),γγ-coin, linear polarization, DSA,γ(t).75Se deduced levels,I, π, τ, δ(E2/M1), B(σλ). Enriched targets, Ge detectors. 相似文献
13.
Ulrich Mayerhofer T. von Egidy J. Jolie H. G. Börner G. Colvin S. Judge B. Krusche S. J. Robinson K. Schreckenbach S. Brant V. Paar 《Zeitschrift für Physik A Hadrons and Nuclei》1991,341(1):1-8
Gamma rays of199Au obtained after double neutron capture in197Au were measured at the ILL high flux reactor. A level scheme up to 1770 keV excitation energy is established. The result is compared with IBFM and Boson-Fermion-Symmetry calculations. 相似文献
14.
Periodic Nodal Surfaces (PNS) of Fourier series are derived and classified as fundamental invariants of structured matter. Relationships to periodic minimal surfaces PMS and to periodic zero potential surfaces (POPS) are given. A basic set of cubic PNS is represented in arithmetic form. The special importance of the invariance of the zeros to the type of the potential is stressed. 相似文献
15.
16.
17.
The syntheses of two rigid organic molecular rods bearing a nitronyl-nitroxide radical and a terminal nitrogen-based functionality like a pyridine or a cyano group are reported. Both new paramagnetic molecules are fully characterized, including crystal structure analysis. Furthermore their magnetic behaviours in the crystalline state are investigated and their spin concentration corroborate their excellent purity. While the pyridine functionalized rod is synthesized by converting the corresponding benzaldehyde to the phenyl-nitronyl-nitroxide radical, the synthesis of the cyano functionalized rod demonstrates the accessibility of highly sophisticated spin-labelled molecules via cross-coupling reaction with a meta-iodo-phenyl-nitronyl-nitroxide moiety. 相似文献
18.
Heiko Herrmann W. Muschik G. Rückner H.-H. von Borzeszkowski 《Foundations of Physics》2004,34(6):1005-1021
The 24 components of the relativistic spin tensor consist of 3 + 3 basic spin fields and 9 + 9 constitutive fields. Empirically only three basic spin fields and nine constitutive fields are known. This empirem can be expressed by two spin axioms, one of them denying purely relativistic spin fields, and the other one relating the three additional basic fields and the nine additional constitutive fields to the known (and measurable) ones. This identification by the spin axioms is material-independent and does not mix basic spin fields with constitutive properties. The approaches to the Weyssenhoff fluid and the Dirac-electron fluid found in literature are discussed with regard to these spin axioms. The conjecture is formulated, that another reduction from six to three basic spin fields which does not obey the spin axioms introduces special material properties by not allowed mixing of constitutive and basic fields. 相似文献
19.
A. Roberts M. L. von Bibra H-P. Gemünd E. Kreysa 《International Journal of Infrared and Millimeter Waves》1994,15(3):505-517
In this paper a comparison between a rigorous electromagnetic model for transmission through a hexagonal array of circular waveguides in a series of thick, metallic screens and experimental measurements in the far infrared is made. It is found that there is excellent agreement between theory and experiment when the frequency is below that where any diffracted orders propagate. The agreement is still very good above this frequency. Below a frequency approximately equal to the cut-off frequency of the circular waveguides little power is transmitted. As the thickness of the screen is increased, this decrease in transmission becomes more abrupt. Also, for thick screens, resonances appear in the transmission spectrum which are analogous to those which appear in the spectra of two grids separated by a distance comparable to the wavelength of the radiation being used. 相似文献
20.
Y. Akiyama P. von Brentano A. Gelberg 《Zeitschrift für Physik A Hadrons and Nuclei》1987,326(4):517-521
Energies of collective levels in178Hf and234U are compared with predictions of theSU (3) limit of thesdg Interacting Boson Model. All known positive parity states of178Hf below 1.8 MeV (with the exception of a 0+ band) have been satisfactorily reproduced. Most of the bands in234U are also described by the model. However, a few predicted states have no experimental counterpart. The introduction of theg-bosons strongly reduces the previously observed discrepancies between experimentalB(E2)'s in238U and thesd-IBM calculation. 相似文献