全文获取类型
收费全文 | 899636篇 |
免费 | 8872篇 |
国内免费 | 2572篇 |
专业分类
化学 | 470018篇 |
晶体学 | 13096篇 |
力学 | 43045篇 |
综合类 | 33篇 |
数学 | 118670篇 |
物理学 | 266218篇 |
出版年
2021年 | 7704篇 |
2020年 | 8447篇 |
2019年 | 9436篇 |
2018年 | 12087篇 |
2017年 | 12113篇 |
2016年 | 17904篇 |
2015年 | 10665篇 |
2014年 | 17035篇 |
2013年 | 40779篇 |
2012年 | 30937篇 |
2011年 | 37413篇 |
2010年 | 27074篇 |
2009年 | 26809篇 |
2008年 | 34761篇 |
2007年 | 34353篇 |
2006年 | 31810篇 |
2005年 | 28565篇 |
2004年 | 26360篇 |
2003年 | 23588篇 |
2002年 | 23253篇 |
2001年 | 25218篇 |
2000年 | 19553篇 |
1999年 | 15377篇 |
1998年 | 12925篇 |
1997年 | 12660篇 |
1996年 | 12141篇 |
1995年 | 11052篇 |
1994年 | 10908篇 |
1993年 | 10461篇 |
1992年 | 11592篇 |
1991年 | 11837篇 |
1990年 | 11474篇 |
1989年 | 11166篇 |
1988年 | 11115篇 |
1987年 | 10913篇 |
1986年 | 10371篇 |
1985年 | 13514篇 |
1984年 | 13889篇 |
1983年 | 11394篇 |
1982年 | 11795篇 |
1981年 | 11449篇 |
1980年 | 10755篇 |
1979年 | 11611篇 |
1978年 | 11969篇 |
1977年 | 11869篇 |
1976年 | 11641篇 |
1975年 | 10984篇 |
1974年 | 10843篇 |
1973年 | 10931篇 |
1972年 | 7846篇 |
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
971.
M. Tukhtasinov 《Ukrainian Mathematical Journal》2004,56(2):283-295
Within the framework of the theory of games, we consider the problem of starting control of oscillations of points of a string according to a given law. As control parameters for players, the initial position and the starting velocity of the string are taken. We determine the optimal control for players in both discrete case and continuous case. 相似文献
972.
The European Physical Journal C - The physics prospects of the LHCb experiment are presented here for precision CP violation measurements and rare decays. 相似文献
973.
O. A. Anikeenok 《Physics of the Solid State》2003,45(5):854-858
In solid-state physics, a crystal lattice is frequently approximated by an array of interacting ions. In this case, the wave functions of individual ions are assumed to be a fairly good zeroth approximation in calculating the matrix elements of the interaction Hamiltonian of electrons and nuclei of the lattice from first principles. Use of the second-quantization method is proposed for such calculations in the basis of these functions. As an example, the electron transition amplitude from a ligand to the central ion is estimated. The results agree well with the experimental data. 相似文献
974.
975.
A double monochromator is developed and manufactured on the basis of an acousto-optic filter made of a potassium dihydrogen phosphate (KDP) single crystal. The device has an operating range of 260–540 nm and improved optical characteristics: high aperture ratio (an angular aperture of 2° and a linear aperture of 6.5x15 mm), high polarization contrast (~108), and low level of transmission sidelobes (~103). The spectral resolution of the monochromator at the edges of the operating range is 0.5 and 3 nm, respectively. The control frequency band is 60–150 MHz. Experimentally, it is shown that, for sound beams with equivalent geometric parameters, the diffraction efficiency provided by the KDP-based acousto-optic filter is an order of magnitude higher than that obtained with a noncollinear acousto-optic filter fabricated on the basis of crystalline quartz. 相似文献
976.
977.
Polyphenols of Certain Plants of the Euphorbiaceae Family 总被引:1,自引:0,他引:1
N. G. Abdulladzhanova S. M. Mavlyanov D. N. Dalimov 《Chemistry of Natural Compounds》2003,39(4):399-400
978.
D. Kaneko T. Narita J. P. Gong Y. Osada J. Ando K. Yamamoto S. Ohnishi V. V. Yaminsky 《Journal of Polymer Science.Polymer Physics》2003,41(22):2808-2815
The effect of the shear flow on the thickness change of a polyelectrolyte membrane grafted onto a glass substrate was directly investigated with a flow cell combined with a confocal laser scanning microscope. The membrane thickness decreased proportionally to an increase in the shear stress of the flow when the shear rate exceeded a critical value of 1 s?1. The higher the ionic strength was of the fluid, the greater the thinning effect was. The correlation between the critical shear rate and the relaxation of the polymer in the gel membrane was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2808–2815, 2003 相似文献
979.
Summary The detachment of a rubber matrix from a rigid inclusion under monotonic loading and at subsequent relaxation is investigated within two dimensional analysis. Examined are stress–strain experimental data acquired with the help of a test bed equipped with a digital image-acquisition device. The influence of the interfacial bonding strength and the particle size on the detachment process is analyzed. The influence of the interfacial bonding strength is visible in the stress–strain diagram of loading and in the recorded images. The relaxation test reveals no influence of the bonding strength on the stress-relaxation. However, the image analysis indicates a secondary transient creep of the contour of detachment, which depends on the interfacial bonding. 相似文献
980.
A. Rusetsky 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):491-494
In the perturbative field-theoretical models we investigate the inclusion of the electromagnetic interactions into the purely strong theory that describes hadronic processes. In particular, we study the convention for splitting electromagnetic and strong interactions and the ambiguity of such a splitting. The issue of the interpretation of the parameters of the low-energy effective field theory in the presence of electromagnetic interactions is addressed, as well as the scale and gauge dependence of the effective theory couplings. We hope, that the results of these studies are relevant for the electromagnetic sector of ChPT.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.40.Ks Electromagnetic corrections to strong- and weak-interaction processes - 13.40.Dk Electromagnetic mass differences - 11.30.Rd Chiral symmetries - 11.10.Hi Renormalization group evolution of parameters 相似文献