全文获取类型
收费全文 | 1235篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
化学 | 933篇 |
晶体学 | 3篇 |
力学 | 22篇 |
数学 | 174篇 |
物理学 | 127篇 |
出版年
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 14篇 |
2019年 | 17篇 |
2018年 | 9篇 |
2016年 | 20篇 |
2015年 | 11篇 |
2014年 | 21篇 |
2013年 | 28篇 |
2012年 | 43篇 |
2011年 | 41篇 |
2010年 | 23篇 |
2009年 | 24篇 |
2008年 | 46篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 33篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 39篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 16篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1992年 | 9篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 25篇 |
1985年 | 29篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 27篇 |
1981年 | 31篇 |
1980年 | 28篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1977年 | 20篇 |
1976年 | 14篇 |
1975年 | 12篇 |
1972年 | 10篇 |
1966年 | 9篇 |
1965年 | 11篇 |
排序方式: 共有1259条查询结果,搜索用时 15 毫秒
11.
Dr. J. Dembczyński W. Ertmer U. Johann P. Stinner 《Zeitschrift für Physik A Hadrons and Nuclei》1980,294(4):313-317
The hyperfine structure of the metastable atomic states (3d 74s)5 F 2,3,4,5 and (3d 7 4s)3 F 2,3,4 of57Fe has been measured using theABMR- LIRF method (atomic beam magnetic resonance detected by laser induced resonance fluorescence). From these measurements the following hfs constantsA of the magnetic dipole interaction have been obtained (corrected for second order effects):A(5 F 2)=55.994(7) MHzA(5 F 3)=69.632(5) MHzA(5 F 4)=78.435(4) MHzA(5 F 5)=87.246(3) MHzA(3 F 2)=143.328(4) MHzA(3 F 3)=50.602(10) MHzA(3 F 4)=13.456(5) MHz 相似文献
12.
Anne Seebach Christoph von Rohden Johann Ilmberger Stephan M. Weise Kay Knöller 《Isotopes in environmental and health studies》2013,49(3):291-298
This study presents selected results, applying environmental tracers to investigate lake water–groundwater interactions at two study sites located in Lusatia, Germany. The focus of the investigations were two meromictic pit lakes and their adjacent aquifers. In order to follow hydrodynamic processes between lake and groundwater, mixing patterns within the lakes as well as ages of lake and groundwater, water samples of ground- and lake water were collected at three occasions, representing summer and winter conditions in the aquatic systems. The water samples were analysed for stable isotopes (deuterium, oxygen-18) and tritium and sulphurhexafluoride (SF6 concentration). Lake water profiles of conductivity and 18O could validate the permanent stratification pattern of both the lakes. Groundwater data sets showed a heterogeneous local distribution in stable isotope values between rain and lake water. A two-component mixing model had been adopted only from 18O data to determine lake water proportions in the surrounding groundwater wells in order to correct measured tritium and SF6 concentrations in groundwater samples. This procedure had been hampered by upstream-located wells indicating strong 18O enrichment in groundwater samples. However, rough groundwater ages were estimated. For both study sites, Piston flow ages between 12.9 and 27.7 years were calculated. The investigations showed the good agreement between two different environmental dating tools, considering the marginal data sets. 相似文献
13.
Johann Summhammer 《Foundations of Physics Letters》1988,1(2):113-137
In quantum physics all experimental information is discrete and stochastic. But the values of physical quantities are considered to depict definite properties of the physical world. Thus physical quantities should be identified with mathematical variables which are derived from the experimental data, but which exhibit as little randomness as possible. We look for such variables in two examples by investigating how it is possible to arrive at a value of a physical quantity from intrinsically stochastic data. With the aid of standard probability calculus and elementary information theory, we are necessarily led to the quantum theoretical phases and state vectors as the first candidates for physical quantities. 相似文献
14.
Ramesh-Babu Adusumalli Rejin Raghavan Rudy Ghisleni Tanja Zimmermann Johann Michler 《Applied Physics A: Materials Science & Processing》2010,100(2):447-452
The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars
machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large
scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure.
With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure
mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio
embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging
because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear
or kink band. 相似文献
15.
Daniel S. Covita Dimitrios F. Anagnostopoulos Hermann Fuhrmann Hubert Gorke Detlev Gotta Alexander Gruber Albert Hirtl Tomoichi Ishiwatari Paul Indelicato Thomas S. Jensen Eric-Olivier Le Bigot Valeri E. Markushin Michael Nekipelov Vladimir N. Pomerantsev Vladimir P. Popov Joaquim M. F. dos Santos Philipp Schmid Leopold M. Simons Marian Theisen Martino Trassinelli Joao F. C. A. Veloso Johann Zmeskal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2018,72(4):72
16.
Nadine Werth Mathias S. Müller Johann Meier Alexander W. Koch 《Optics Communications》2011,284(9):2317-2322
Using Laser-based Speckle-Interferometers, the shape of optically rough surfaces can be measured precisely and contactlessly from variable measuring distances even in regions of difficult access. This work is concerned with the integration of a micromirror array (MMA) into an electronic Speckle-Pattern-Interferometer. With the adaptive optics, it is intended to adapt the phasefront of a reference wave to critical surface areas of the measurement object. Yet, due to the topography of the MMA, diffraction effects occur which affect the phase and intensity of the generated wavefront. We demonstrate how these diffraction effects can be efficiently modelled by a Fraunhofer diffraction method. We compare the results of this model to theoretical data obtained by a numerical Fresnel diffraction model and to measurement data obtained from a measurement setup incorporating a multi mirror array. 相似文献
17.
Johann Zmeskal 《Progress in Particle and Nuclear Physics》2008,61(2):512-550
Strong interaction processes were intensively studied at low energy with exotic atoms, touching one of the fundamental problems in hadron physic today — the still unsolved question of how hadron masses are generated. The question of the origin of the large hadron masses made up of light quarks, the current mass of the up (u) and down (d) quarks (mu,d≈5 MeV) is two orders of magnitude smaller than a typical hadron mass of about 1 GeV, will be discussed in the context with the experimental work done in the field of exotic atoms expanded to exotic nuclei.An overview of the properties of exotic hydrogen atoms made of pions and kaons are presented, using high precision experiments unrevealing the nature of strong interaction physics at low energy. A new field which contributes to the understanding of the origin of the large hadron mass is the study of the mass modification in a nuclear medium. Antikaon mediated bound nuclear systems would be an ideal tool, if they exist, to look for chiral restoration at high density and zero temperature or even more exotic to look for phase transitions. 相似文献
18.
H. Jara K. Boyer U. Johann T. S. Luk I. A. McIntyre A. McPherson C. K. Rhodes 《Applied physics. B, Lasers and optics》1987,42(1):11-15
The results of transient loss measurements performed in a self-sustained discharge KrF* amplifier are reported. Analysis of these results gives a minimum value of 20 for the effective gain to loss ratiog
0/eff, indicating that efficient extraction of energy in subpicosecond KrF* amplifiers in the 1 J range should be achievable. 相似文献
19.
In this brief review, an overview about recent efforts to simulate the spectroscopic signatures of chiral molecules is given with focus on real time propagation approaches to solve the time-dependent Schrödinger equation. In particular the simulation of electric circular dichroism spectra and vibrational Raman optical activity is discussed. In comparison to linear absorption spectra, where only the response of the electric dipole moment is necessary, the response of the magnetic dipole moment and electric quadrupole moment is more intricate. Issues such as gauge origin dependence, basis set dependence, non-local potentials and the dipole approximation are addressed. 相似文献
20.