全文获取类型
收费全文 | 3905篇 |
免费 | 28篇 |
国内免费 | 2篇 |
专业分类
化学 | 2415篇 |
晶体学 | 14篇 |
力学 | 57篇 |
综合类 | 1篇 |
数学 | 517篇 |
物理学 | 931篇 |
出版年
2016年 | 29篇 |
2015年 | 40篇 |
2014年 | 31篇 |
2013年 | 72篇 |
2012年 | 66篇 |
2011年 | 97篇 |
2010年 | 52篇 |
2009年 | 51篇 |
2008年 | 62篇 |
2007年 | 101篇 |
2006年 | 64篇 |
2005年 | 65篇 |
2004年 | 67篇 |
2003年 | 49篇 |
2002年 | 42篇 |
2001年 | 36篇 |
1999年 | 27篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 38篇 |
1992年 | 26篇 |
1991年 | 26篇 |
1990年 | 27篇 |
1987年 | 30篇 |
1986年 | 26篇 |
1984年 | 34篇 |
1983年 | 35篇 |
1982年 | 35篇 |
1981年 | 39篇 |
1980年 | 31篇 |
1979年 | 32篇 |
1978年 | 36篇 |
1976年 | 34篇 |
1959年 | 90篇 |
1958年 | 149篇 |
1957年 | 187篇 |
1956年 | 51篇 |
1936年 | 31篇 |
1935年 | 29篇 |
1933年 | 33篇 |
1932年 | 31篇 |
1931年 | 29篇 |
1930年 | 53篇 |
1929年 | 56篇 |
1928年 | 74篇 |
1927年 | 48篇 |
1926年 | 32篇 |
1925年 | 33篇 |
1904年 | 24篇 |
1889年 | 26篇 |
排序方式: 共有3935条查询结果,搜索用时 31 毫秒
61.
The influence of the oxygen content on the saturation magnetic moment and the Curie temperature was studied experimentally on non-stoichiometric manganese ferrites having a varying excess of manganese. Taking into consideration the results of studying the electrical conductivity and magnetic relaxation effects, a model was elaborated for the distribution of ions in these ferrites, which starts out from the distribution of ions in stoichiometric manganese ferrite. The experimental results obtained by us and those of other authors confirm the justification of this model.
In conclusion the authors thank members of their technological department for preparing the samples and M. Mikulá for carefully carrying out the chemical analyses. 相似文献
II. Mn1+xFe2-xO4+y
. , . .
In conclusion the authors thank members of their technological department for preparing the samples and M. Mikulá for carefully carrying out the chemical analyses. 相似文献
62.
A model for the distribution of cations in the spinel lattice of manganese ferrites MnFe2O4+
was elaborated on the basis of the experimental studies of the basic magnetic quantities, electrical conductivity and magnetic relaxation of the given ferrites, taking into consideration their crystallographic properties. The conclusions following from this model are in good agreement with the experimental results obtained by us and by other authors both for stoichiometric manganese ferrite and for a ferrite where 0.
I. MnFe2O4+
, MnFe2O4+ . , , , , , 0.相似文献
63.
64.
D. Drijard H. G. Fischer W. Geist P. G. Innocenti V. Korbel A. Minten A. Norton S. Stein O. Ullaland H. D. Wahl G. Fontaine C. Ghesquière G. Sajot P. Hanke W. Hofmann M. Panter K. Rauschnabel J. Spengler D. Wegener H. Frehse M. Heiden E. E. Kluge A. Putzer M. Della Negra D. Linglin R. Gokieli R. Sosnowski 《Zeitschrift fur Physik C Particles and Fields》1981,9(4):293-303
Inclusive production of ?0,f, andg 0 mesons and ofK s 0 ,K *0 (892), ? andK *0(1430)mesons has been measured at <y>~2.6 and <p T >~1.1 GeV/c in proton-proton interactions at \(\sqrt s = 52.5\) GeV. The negative particle from the two-body decays of these resonances were identified by a threshold Cerenkov counter and used for triggering. Starting from the measured differential cross section, total inclusive cross sections for the vector and tensor mesons were determined using various parametrizations for they andp T dependence of the differential cross section. The experimental results are discussed in the framework of production models based on the parton picture. The strangeness suppresion factor λ=(0.30±0.10) due toSU(3) symmetry breaking of the quark sea is derived. 相似文献
65.
66.
Zero-temperature magnetic phase transitions exhibit an abundance of nearly critical magnetic fluctuations that allow to probe
the traditional concepts of the metallic state. For the prototypical heavy-fermion compound, CeCu6−x
Au
x
, a breakdown of the Fermi-liquid properties may be tuned by Au concentration, hydrostatic pressure, or magnetic field. The
d-electron weak itinerant ferromagnet ZrZn2, on the other hand, was recently found to display superconductivity in coexistence with ferromagnetism. 相似文献
67.
Summary Let W(t) be a standard Wiener process with occupation density (local time) (x, t). Paul Lévy showed that for each x, (x, t) is a.s. equal to the mesure du voisinage of W, i.e., to the limit as h approaches zero of h
1/2 times N(h, x, t), the number of excursions from x, exceeding h in length, that are completed by W up to time t. Recently, Edwin Perkins showed that the exceptional null sets, which may depend on x, can be combined into a single null set off which the above convergence is uniform in x. The main aim of the present paper is to estimate the rate of convergence in Perkins' theorem as h goes to zero. We also investigate the connection between N and in the case when we observe a Wiener process through a long time t and consider the number of long (but much shorter than t) excursions.Research partially supported by a NSERC Canada grant 相似文献
68.
Quantum systems whose classical counterpart have ergodic dynamics are quantum ergodic in the sense that almost all eigenstates are uniformly distributed in phase space. In contrast, when the classical dynamics is integrable, there is concentration of eigenfunctions on invariant structures in phase space. In this paper we study eigenfunction statistics for the Laplacian perturbed by a delta-potential (also known as a point scatterer) on a flat torus, a popular model used to study the transition between integrability and chaos in quantum mechanics. The eigenfunctions of this operator consist of eigenfunctions of the Laplacian which vanish at the scatterer, and new, or perturbed, eigenfunctions. We show that almost all of the perturbed eigenfunctions are uniformly distributed in configuration space. 相似文献
69.
Calculations on Rydberg states are performed using quantum Monte Carlo methods. Excitation energies and singlet-triplet splittings are calculated for two model systems, the carbon atom (3P and 1P) and carbon monoxide ((1Sigma and 3Sigma). Kohn-Sham wave functions constructed from open-shell localized Hartree-Fock orbitals are used as trial and guide functions. The fixed-node diffusion quantum Monte Carlo (FN-DMC) method depends strongly on the wave function's nodal hypersurface. Nodal artefacts are investigated for the ground state of the carbon atom. Their effect on the FN-DMC results can be analyzed quantitatively. FN-DMC leads to accurate excitation energies but to less accurate singlet-triplet splittings. Variational Monte Carlo calculations are able to reproduce the experimental results for both the excitation energies and the singlet-triplet splittings. 相似文献
70.
Benfatto M Della Longa S Hatada K Hayakawa K Gawelda W Bressler C Chergui M 《The journal of physical chemistry. B》2006,110(29):14035-14039
A full multiple theoretical model (MXAN) is applied to fit picosecond difference X-ray absorption spectra at the ruthenium L(3) edge upon photoexcitation of aqueous [RuII(bpy)3]2+. We show that fitting difference spectra allows an increase in sensitivity, such that slight structural changes can be retrieved, which are not detected in fitting full spectra. The Ru-N bond distances of the excited complex in the (3)MLCT state are in good agreement with recently published values. The implementation of the present approach to L-edge spectra and its high sensitivity opens opportunities for its extension to a large class of experiments where difference X-ray absorption spectra are recorded. 相似文献