全文获取类型
收费全文 | 396236篇 |
免费 | 3931篇 |
国内免费 | 1029篇 |
专业分类
化学 | 213162篇 |
晶体学 | 5783篇 |
力学 | 17800篇 |
综合类 | 15篇 |
数学 | 44583篇 |
物理学 | 119853篇 |
出版年
2019年 | 3359篇 |
2018年 | 4358篇 |
2017年 | 4316篇 |
2016年 | 6644篇 |
2015年 | 4048篇 |
2014年 | 6401篇 |
2013年 | 16391篇 |
2012年 | 12443篇 |
2011年 | 15415篇 |
2010年 | 10748篇 |
2009年 | 10524篇 |
2008年 | 14272篇 |
2007年 | 14561篇 |
2006年 | 13686篇 |
2005年 | 12448篇 |
2004年 | 11252篇 |
2003年 | 10098篇 |
2002年 | 10017篇 |
2001年 | 10776篇 |
2000年 | 8397篇 |
1999年 | 6501篇 |
1998年 | 5674篇 |
1997年 | 5622篇 |
1996年 | 5294篇 |
1995年 | 4905篇 |
1994年 | 5054篇 |
1993年 | 4651篇 |
1992年 | 5315篇 |
1991年 | 5380篇 |
1990年 | 5159篇 |
1989年 | 5052篇 |
1988年 | 5058篇 |
1987年 | 4890篇 |
1986年 | 4648篇 |
1985年 | 6166篇 |
1984年 | 6481篇 |
1983年 | 5414篇 |
1982年 | 5719篇 |
1981年 | 5546篇 |
1980年 | 5454篇 |
1979年 | 5538篇 |
1978年 | 5972篇 |
1977年 | 5772篇 |
1976年 | 5883篇 |
1975年 | 5479篇 |
1974年 | 5583篇 |
1973年 | 5729篇 |
1972年 | 3961篇 |
1971年 | 3396篇 |
1970年 | 3085篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
N. F. Morozov Yu. K. Startsev Yu. V. Sud’enkov A. A. Suslikov G. A. Baranov A. A. Belyaev 《Technical Physics》2006,51(7):872-877
The radiation hardness and mechanical strength of single-and two-phase glasses are studied for the case when nanosecond laser pulses (λ= 1.06 μm, τ0.5 ≈ 12.5 ns) are focused inside the material. Laser interferometry is applied to measure the displacement of the free surface, find optical breakage thresholds, and carry out the fractographic analysis of damaged regions. It is shown that breakdown channels and damage regions develop in a nonlinear manner according to optical breakdown mechanisms, changing each other with an increase in the laser energy. The strength of the two-phase glass is found to be more than four times that of the single-phase glass, although their elastic properties differ insignificantly. Such a considerable difference in the hardness of these materials with chemically similar constitutents is attributed to the presence of the double-lattice nanometer-scale structure of the two-phase glass. 相似文献
992.
This paper presents an innovative application of Augmented Reality (AR) techniques in the field of industrial engineering
in which the user explores data from numerical simulations or the results of measurements and experiments, superimposed to
the real object that they refer to. The user observes the object through a tablet PC, used as a video see-through handheld
display. Data are visualized superimposed to the real object that represents a spatial reference relative to which the user
can refer to, so the exploration is more natural compared to a traditional visualization software. Moreover, we have developed
a new framework, called VTK4AR, that provides a set of useful software classes for the rapid development of AR applications
for scientific visualization. VTK4AR is built on top of VTK (an open source API for scientific visualization), so it will
be possible to employ a wide range of visualization techniques in many application fields, and moreover, it is possible to
interactively manipulate data-sets in order to achieve a more effective way of visualization. 相似文献
993.
N. G. Rachkova I. I. Shuktomova A. I. Taskaev 《Russian Journal of Applied Chemistry》2006,79(5):715-721
Sorption of U, Ra, and Th from multicomponent aqueous salt solutions on hydrolyzed wood lignin is studied. The mechanism of radionuclide sorption from saline solutions is suggested on the basis of the results of sequential extraction. 相似文献
994.
V. N. Kizhnyaev A. F. Pokatilov L. I. Vereshchagin L. V. Adamova A. P. Safronov A. I. Smirnov 《Russian Journal of Applied Chemistry》2006,79(7):1167-1173
Carbon-chain polymers with 1,3,4-oxadiazole rings were prepared by radical polymerization and polymer-analogous transformations. The kinetic relationships of the polymerization of vinyl-1,3,4-oxadiazole monomers and some properties of the resulting polymers were studied. The thermodynamics of interaction of poly-2-vinyl-5-methyl-1,3,4-oxadiazole, a nonionic water-soluble polymer, with water was examined. 相似文献
995.
V. M. Lembrikov V. V. Volkova G. P. Zhavoronkova L. V. Konyakhina 《Russian Journal of Applied Chemistry》2006,79(2):196-200
Data on the equilibrium distribution of phosphoric acid among the aqueous and organic phases in extraction of phosphoric acid with tri-n-butyl phosphate are presented for the system constituted by phosphoric acid produced from the Khibiny concentrate and by the extracting agent from the industrial system for purification of extraction phosphoric acid at 25–50°C. 相似文献
996.
P. K. Sazonov G. A. Artamkina I. P. Beletskaya 《Russian Journal of Organic Chemistry》2006,42(3):438-447
The nucleophilic aromatic and vinyl substitution using diaza-18-crown-6 as nucleophile afforded a number of its N,N’-diaryl-[aryl = 2,4-(NO2)2C6H3, 4-C5F4N, 4-CF3C6F4] and N,N’-dialkenyl-substituted derivatives [alkenyl = PhC(O)CH=CH, MeOCOCH=CH, (EtO2C)2C=C(Ph), etc.]. Arylation of diaza-18-crown-6 with nonactivated aryl bromides, such as 4-Me2NC6H4Br, 4-MeOC6H4Br, C6H5Br, and 4-CF3C6H4Br, was effected under catalysis by palladium complexes. N,N’-Diaryldiaza-18-crowns-6 having electron-acceptor substituents in the aromatic rings turned out to be incapable of forming complexes with metal cations, while their analogs containing electron-donor para-methoxy and para-dimethylamino groups gave complexes with barium perchlorate. 相似文献
997.
Within the framework of fractal analysis and percolation theory, an alternative model of reinforcement of filled polymers
is offered. Practically, this model can be used only to describe the reinforcement of nanocomposites, because, according to
the treatment considered, a pronounced reinforcement can be reached only at ratios of filler particle diameter to the statistical
segment length of about 10 and less. A theoretical calculation showed a good qualitative and quantitative agreement with experiments.
The type of reinforcement mechanism of composites is determined by the type of the space (fractal or Euclidean) in which the
structure of the polymeric matrix is formed.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 797–802, November–Decem ber, 2006. 相似文献
998.
B. D. Kabulov K. A. Akhundzhanov F. U. Yunusov O. A. Shpigun S. S. Negmatov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):354-356
The hydrolytic polycondensation of tetraethoxysilane in the presence of various polymers (polyacrylonitrile, polycaproamide, and chitosan) as templates was performed with the use of the sol-gel technology to obtain nanohybrid composite polymer-silica sorbents-nanofractals. 相似文献
999.
1000.
E. Baggio Saitovitch F. J. Litterst I. Souza Azevedo R. B. Scorzelli 《Hyperfine Interactions》1989,50(1-4):529-535
The Mössbauer spectra of YBa2(Cu1?x Fe x )3O7 at room temperature show several doublets attributed to Fe in Cu(1) sites with different oxygen configurations. Here we present a systematic study performed at 4.2 K forx=0.005, 0.01, 0.03, 0.05, 0.10, 0.15. To obtain information about the magnetic ordered state two samples, withx=0.005 andx=0.15, have been studied at 4.2 K underB ext=5 T. The Mössbauer spectra indicate that the iron moments are polarized forx=0.005, while in the ordered state (x=0.15) they have an antiferromagnetic or spin-glass-like arrangement with high anisotropy. 相似文献