全文获取类型
收费全文 | 3294篇 |
免费 | 31篇 |
国内免费 | 13篇 |
专业分类
化学 | 1924篇 |
晶体学 | 16篇 |
力学 | 59篇 |
数学 | 775篇 |
物理学 | 564篇 |
出版年
2022年 | 30篇 |
2021年 | 29篇 |
2020年 | 21篇 |
2019年 | 23篇 |
2018年 | 33篇 |
2017年 | 32篇 |
2016年 | 54篇 |
2015年 | 52篇 |
2014年 | 59篇 |
2013年 | 114篇 |
2012年 | 97篇 |
2011年 | 691篇 |
2010年 | 76篇 |
2009年 | 94篇 |
2008年 | 111篇 |
2007年 | 89篇 |
2006年 | 102篇 |
2005年 | 93篇 |
2004年 | 84篇 |
2003年 | 55篇 |
2002年 | 78篇 |
2001年 | 68篇 |
2000年 | 76篇 |
1999年 | 47篇 |
1998年 | 52篇 |
1997年 | 56篇 |
1996年 | 50篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 39篇 |
1992年 | 31篇 |
1991年 | 38篇 |
1990年 | 55篇 |
1989年 | 38篇 |
1988年 | 39篇 |
1987年 | 41篇 |
1986年 | 37篇 |
1985年 | 56篇 |
1984年 | 59篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 20篇 |
1980年 | 28篇 |
1979年 | 25篇 |
1978年 | 22篇 |
1977年 | 31篇 |
1976年 | 29篇 |
1975年 | 16篇 |
1974年 | 19篇 |
1973年 | 31篇 |
排序方式: 共有3338条查询结果,搜索用时 15 毫秒
61.
V. Slugeň J. Lipka I. Tóth J. Haščík M. Lehota I. Smieško 《Czechoslovak Journal of Physics》2001,51(9):909-916
Magnetic phases of corrosion products from nuclear power plant WWER-440 (Jaslovské Bohunice) steam generators and secondary circuit pipes were investigated using transmission Mössbauer spectroscopy technique. The main components of secondary circuit’s corrosion products are magnetite (Fe3O4) and hematite (α-Fe2O3) in different ratios. The results can be used for optimal control and maintenance of WWER-440 nuclear reactors as well as for optimisation of water chemistry regime. 相似文献
62.
用于摄像机定位的单目视觉方法研究 总被引:4,自引:1,他引:4
利用单目视觉算法确定摄像机相对于被测点的聚焦位置的方法 ,提出了一种新的能量谱 熵函数图像聚集锋利性测度评价函数以及新的单目视觉测量方法 ,即将单目视觉方法中的离焦法和聚焦法结合起来 ,进行聚焦位置的测量。并给出了用于摄像机定位的单目视觉离集法和聚焦法的计算模型。实验验证结果证明了算法的稳定性和可靠性 相似文献
63.
The motion of a pair of uniform interacting spherical mesoscopic particles situated in a viscous fluid under the influence of a rotating magnetic field was studied. The coupling interactions between the particles were chosen as a superposition of steric and dipolar pair potentials (for the dipoles parallel to the external field). The model dynamics consisting of particular rotation and vibration modes is the result of the interplay of viscous and interaction forces. The transition from the synchronous to the asynchronous regime of dimer rotation has been found. The results were discussed from a synergetic point of view. A qualitative picture of behaviour of the effective magnetoviscosity and permittivity for dimerized magnetorheological suspension has been given. 相似文献
64.
I. Alfter E. Bodenstedt B. Hamer J. van den Hoff W. Knichel H. Münning S. Piel R. Sajok J. Schüth 《Zeitschrift für Physik A Hadrons and Nuclei》1993,345(3):273-283
Theg-factors of the four lowest states of the ground state rotational band of158Dy have been determined asg(2 1 + )=+0.362(23),g(4 1 su+ )=+0.340(20),g(6 1 su+ )=+0.207(36) andg(8 1 su+ )=+0.21(11). Theg-factors of the 2+ and 4+ states were measured by the IPAC method with radioactive samples of 2.4 h158Er in external magnetic fields. To investigate the higher states, for the first time an on-line γ—γ IPAC experiment was performed with the reaction156Gd(α, 2n)158Dy by use of the static hyperfine field of DyGd. 相似文献
65.
Á. Nemcsics L. Tóth L. Dobos Ch. Heyn A. Stemmann A. Schramm H. Welsch W. Hansen 《Superlattices and Microstructures》2010
Self-assembled strain-free quantum dot (QD) structures were grown on AlGaAs surface by the droplet epitaxal method. The QDs were developed from pure Ga droplets under As pressure. The QDs were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Both techniques show that the QDs are very uniform in size and their distribution on the surface is also homogeneous. The high resolution cross-sectional TEM investigation shows perfect lattice matching between the QD and the substrate, and also the faceting of the side walls of QD can be identified exactly by lattice planes. Analytical TEM (elemental mapping by EELS) unambiguously identifies the presence of Al in the QD. 相似文献
66.
67.
W. N. Polyzou Ch. Elster W. Gl?ckle J. Golak Y. Huang H. Kamada R. Skibi��ski H. Wita?a 《Few-Body Systems》2011,49(1-4):129-147
We review the construction and applications of exactly Poincaré invariant quantum mechanical models of few-degree of freedom systems. We discuss the construction of dynamical representations of the Poincaré group on few-particle Hilbert spaces, the relation to quantum field theory, the formulation of cluster properties, and practical considerations related to the construction of realistic interactions and the solution of the dynamical equations. Selected applications illustrate the utility of this approach. 相似文献
68.
69.
70.
Jos�� Fl��vio Marcelino Borges Marlon Luiz Hneda Andr�� Maur��cio Brinatti Jo?o Batista Marimon da Cunha Jadir Aparecido Rosa Jos�� Domingos Fabris 《Hyperfine Interactions》2011,203(1-3):9-15
A sample of the coarse sand fraction from the soil material of the A-horizon (0?C0.2 m from the soil surface) of a dusky red magnetic Oxisol was submitted to high-energy mechanical milling for different times. This assay aimed mainly at (a) monitoring the individualization of strongly aggregated mineral particles, and (b) measuring the effect of the milling pressure on the mineralogy changes of the material. These data are also intended to experimentally subside any physical model describing the mechanical behavior of the superficial soil layer that is subjected to intensive machine management, in agriculture fields. Powder X-ray data reveal that some mineralogical phases, notably gibbsite, disappear soon after the first few hours milling. The 298 K-transmission Mössbauer spectrum for the non-milled sand sample shows a qualitatively typical pattern for the sand fraction of basalt derived soils, with magnetically ordered sextets, assignable mainly to hematite and maghemite, and an intense central (super)paramagnetic Fe3?+? doublet. For the milled samples, spectra revealed progressive spectral reduction of the magnetic hyperfine structure, with concomitant increase of relative subspectral areas due to (super)paramagnetic phases, as the milling time increased. This result is consistent with the reduction of measured saturation magnetization, from 4.96(8) J T???1 kg???1, for the non-milled sample, to 3.26(7) J T???1 kg???1, for the sample milled for 8 hours. 相似文献