全文获取类型
收费全文 | 1249篇 |
免费 | 45篇 |
国内免费 | 4篇 |
专业分类
化学 | 738篇 |
晶体学 | 6篇 |
力学 | 31篇 |
数学 | 193篇 |
物理学 | 330篇 |
出版年
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 23篇 |
2018年 | 12篇 |
2017年 | 13篇 |
2016年 | 35篇 |
2015年 | 33篇 |
2014年 | 16篇 |
2013年 | 47篇 |
2012年 | 65篇 |
2011年 | 69篇 |
2010年 | 48篇 |
2009年 | 45篇 |
2008年 | 49篇 |
2007年 | 50篇 |
2006年 | 44篇 |
2005年 | 38篇 |
2004年 | 43篇 |
2003年 | 29篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 15篇 |
1998年 | 25篇 |
1997年 | 20篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 21篇 |
1992年 | 17篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 18篇 |
1976年 | 8篇 |
1975年 | 16篇 |
1974年 | 10篇 |
1973年 | 11篇 |
1970年 | 8篇 |
1969年 | 9篇 |
排序方式: 共有1298条查询结果,搜索用时 46 毫秒
131.
J. Arnold B. van den Brandt M. Daum M. Finger M. Finger Jr. J. Franz N. Goujon-Naef P. Hautle R. Hess A. Janata J.A. Konter H. Lacker C. Lechanoine-Leluc F. Lehar S. Mango D. Rapin E. Rössle R. Schirmaier P.A. Schmelzbach M. Schmidt H. Schmitt P. Sereni M. Slunecka A. Teglia B. Vuaridel 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):411-415
Abstact: The kinetic energy spectrum and the polarization of the PSI neutron beam produced in the reaction 12C(p,n)X at 0° with 590 MeV polarized protons were investigated. A strong energy dependence of the neutron beam polarization is
observed which was not expected at the time the neutron beam was built.
Received: 3 April 1998 相似文献
132.
133.
Klaus D. A. Wendt Klaus Blaum Christopher Geppert Peter Müller Wilfried Nörtershäuser Annette Schmitt Philipp Schumann Norbert Trautmann Bruce A. Bushaw 《Hyperfine Interactions》2005,162(1-4):147-157
A variety of research activities in the field of fundamental and applied nuclear physics has evolved in the last years using
resonantly tuned radiation from powerful lasers. The technique of resonance ionization spectroscopy has delivered outstanding
results and found broad acceptance in the last years as a particularly efficient and highly selective method for rare and
exotic radioisotope studies. It is used for production, spectroscopy and detection of these species and provides complete
isobaric, high isotopic and even some isomeric selection, which altogether is needed for on-line investigation of short lived
species far off stability as well as for ultra trace determination. Good overall efficiency pushes the experimental limits
of detection in elemental trace analysis down to below 106 atoms per sample, and additionally isotopic selectivity as high as 3 × 1012 has been demonstrated. The widespread potential of resonance ionization techniques is discussed, focusing on the experimental
arrangements for applications in selective on-line isotope production, spectroscopy of rare radioisotopes and ultra trace
determination of radiotoxic isotopes like 238Pu to 244Pu, 135,137Cs, 89,90Sr or 41Ca in environmental, technical and biomedical samples. 相似文献
134.
135.
The polarization observables for deuteron photodisintegration are given as Hermitean forms of theT-matrix elementst
i
. By inversion we are able to express a given productt
i
*
t
j
in terms of polarization observables. This allows (i) to derive linear relations between observables for unpolarized, circularly and linearly polarized photons, (ii) to construct explicitly complete sets of polarization observables, and (iii) to derive quadratic relations between observables.Supported by the Deutsche Forschungsgemeinschaft (SFB 201) 相似文献
136.
O. Uwira A. Müller J. Linkemann T. Bartsch C. Brandau M. Schmitt A. Wolf D. Schwalm R. Schuch W. Zong H. Lebius W.G. Graham J. Doerfert D.W. Savin 《Hyperfine Interactions》1997,108(1-3):149-154
Recombination of Au49+, Au50+, and Au51+ ions has been studied at the TSR. With Au50+ ions a storage lifetime of only 2 to 4 s was observed with the magnetically expanded electron beam of the cooler at a density
of ne = 107 cm-3. This short storage time is a consequence of the highest recombination rate coefficient ever observed with an atomic ion
(1.8·10-6 cm3 s-1 at zero relative energy Erel = 0 between electrons and ions). At about 30 meV a huge dielectronic recombination resonance is found with a record small
width of only about 15 meV. Such resonances fortuitously occurring near Erel=0 are probably the main reason for the enhanced recombination rates observed with Au50+, with Pb53+ (in a recent experiment at LEAR) as well as with other complex ions. For Au49+ and Au51+ the recombination rates are smaller by an order of magnitude.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
137.
138.
Markus Poppenberg Klaus Schmitt Zhi-Qiang Wang 《Calculus of Variations and Partial Differential Equations》2002,14(3):329-344
Variational techniques are applied to prove the existence of standing wave solutions for quasilinear Schr?dinger equations
containing strongly singular nonlinearities which include derivatives of the second order. Such equations have been derived
as models of several physical phenomena. The nonlinearity here corresponds to the superfluid film equation in plasma physics.
Direct methods of the calculus of variations and minimax methods like the Mountain Pass Theorem are used. The difficulties
introduced by the nonconvex functional are substantially different from the semilinear case.
Received: 21 March 2000 / Accepted: 23 February 2001 / Published online: 25 June 2001 相似文献
139.
R. P. Schmitt T. Botting G. G. Chubarian K. L. Wolf B. J. Hurst H. Jabs M. Hamelin A. Bacak Yu. Ts. Oganessian M. G. Itkis E. M. Kozulin N. A. Kondratiev V. S. Salamatin I. V. Pokrovsky F. Hanappe E. de Goès Brennand A. Huck L. Stuttgé E. Liatard J. Beene R. Varner M. Halbert N. Gan 《Physics of Atomic Nuclei》2003,66(6):1163-1167
The time scales for nuclear fission have been explored using both pre-and postfission neutrons and GDR gamma rays. Four systems were investigated: 133-MeV 16O + 176Yb and 208Pb and 104-MeV 4He + 188Os and 209Bi. Fission fragments were measured in coincidence with PPACs. The neutrons were detected using eight detectors from the DEMON array, while gamma rays were measured using the US BaF2 array. The pre-and postfission gamma rays were determined using moving source fits parallel and perpendicular to the fission fragment emission directions. The time scales for fission for the neutrons were determined using the neutron clock technique. The gamma-ray data were fitted using a statistical model calculation based on the code CASCADE. The results of the fits from both data types were used to extract nuclear friction coefficients, γ, and fission time scales. The γ values ranged from 7 to 20, while the fission times were (31–105)×10?21 s. 相似文献
140.
E. Hlawka Ch. Binder P. Schmitt H. -Chr. Reiochel H. Mitsch F. Schweiger P. Gerl 《Monatshefte für Mathematik》1970,74(3):277-288
Ohne Zusammenfassung 相似文献