全文获取类型
收费全文 | 354403篇 |
免费 | 3558篇 |
国内免费 | 1160篇 |
专业分类
化学 | 184680篇 |
晶体学 | 5928篇 |
力学 | 16062篇 |
综合类 | 4篇 |
数学 | 38211篇 |
物理学 | 114236篇 |
出版年
2020年 | 2800篇 |
2019年 | 3083篇 |
2018年 | 4047篇 |
2017年 | 4013篇 |
2016年 | 6015篇 |
2015年 | 3689篇 |
2014年 | 5933篇 |
2013年 | 15154篇 |
2012年 | 11519篇 |
2011年 | 14209篇 |
2010年 | 10130篇 |
2009年 | 10080篇 |
2008年 | 13349篇 |
2007年 | 13142篇 |
2006年 | 12635篇 |
2005年 | 11491篇 |
2004年 | 10535篇 |
2003年 | 9461篇 |
2002年 | 9344篇 |
2001年 | 11614篇 |
2000年 | 8675篇 |
1999年 | 6758篇 |
1998年 | 5276篇 |
1997年 | 5292篇 |
1996年 | 5013篇 |
1995年 | 4603篇 |
1994年 | 4548篇 |
1993年 | 4466篇 |
1992年 | 5042篇 |
1991年 | 5255篇 |
1990年 | 4893篇 |
1989年 | 4832篇 |
1988年 | 4827篇 |
1987年 | 4724篇 |
1986年 | 4432篇 |
1985年 | 5841篇 |
1984年 | 6037篇 |
1983年 | 4822篇 |
1982年 | 4997篇 |
1981年 | 4798篇 |
1980年 | 4693篇 |
1979年 | 5046篇 |
1978年 | 5231篇 |
1977年 | 5111篇 |
1976年 | 5135篇 |
1975年 | 4722篇 |
1974年 | 4715篇 |
1973年 | 4803篇 |
1972年 | 3287篇 |
1971年 | 2709篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Correlation between the particles from the proton-nucleus interactions in emulsion at 70 GeV/c is presented through the study of the rapidity gap analysis and compared with the two-particle rapidity correlations. It is observed that the strength of correlation decreases as the size of cluster increases. Asymmetry between the forward and backward components were also studied.Authors are thankful to Prof. K. D. Tolstov, JINR, Dubna, USSR for sending the exposed emulsion plates. Thanks are also due to UGC for financial assistance. We sincerely acknowledge the encouragement from Prof. T. Roy. 相似文献
992.
993.
994.
This paper presents results of studies on dc electrical conductivity and transference number measurements on potassium bromate
(KBrO3) complexed polyvinyl chloride (PVC) films prepared by solution cast technique. Temperature dependence of dc electrical conductivity
and transference number data indicated the dominance of ion type charge transport in these specimens. The magnitude of conductivity
increased with increase in concentration of the salt and temperature. Using this (PVC + KBrO3) electrolyte, solid-state electrochemical cells were fabricated, and their discharge profiles were studied under a constant
load of 100 kΩ. Several cell profiles such as open circuit voltage, short circuit current, power density, and energy density
associated with these cells were evaluated and were reported. The features of complexation of the electrolytes were studied
by X-ray diffraction and Fourier transform infrared spectroscopy.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006 相似文献
995.
A. G. Zhdanov A. K. Zvezdin A. P. Pyatakov T. B. Kosykh D. Viehland 《Physics of the Solid State》2006,48(1):88-95
The specific features of the “incommensurate-commensurate” phase transitions induced by a magnetic field in multiferroics
(materials with coexisting magnetic and electric ordering) are considered. These materials are ferroelectromagnets, for example,
bismuth ferrite BiFeO3 and BiFeO3-based compounds, which have spatially modulated spin structures. It is shown that the interaction between the electric and
magnetic subsystems of the multiferroic material can lead to an electric-field-induced shift of the critical magnetic field
corresponding to the transition from a spatially modulated state to a homogeneous antiferromagnetic state. According to the
theoretical estimates obtained for material parameters characteristic of the bismuth ferrite, this shift is of the order of
0.5 T in an electric field of 50 kV/cm. The phase diagrams are constructed in the “electric field-magnetic field” coordinates.
The results of calculations performed in the harmonic incommensurate structure approximation are compared with the exact soliton
solution. 相似文献
996.
A. P. Suponina L. G. Kolzunova M. A. Karpenko 《Russian Journal of Applied Chemistry》2006,79(6):924-929
The effect of coatings based on a copolymer of acrylamide, N,N′-methylenebisaxcrylamide and formaldehyde deposited by electrochemical polymerization on the corrosion resistance of 08Kh18N10T stainless steel (field studies at sea) and low-carbon steel (laboratory experiments) was examined. 相似文献
997.
T. Yu. Gumerov A. F. Dobrynina R. A. Yusupov V. P. Barabanov 《Russian Journal of Applied Chemistry》2006,79(12):1935-1939
The behavior of real disperse systems with organic impurities was examined under conditions of destabilization by inorganic coagulants. A number of physicochemical methods of analysis and a simulation method were used to identify the character and type of the complexes formed and to calculate their stability constants. 相似文献
998.
999.
Using ultra-high vacuum scanning tunneling microscopy (UHV-STM), we show that copper-phthalocyanine (CuPc) grows in a well ordered manner on hydrogen passivated vicinal silicon surfaces. CuPc grows one-dimensionally parallel to the monatomic steps on the vicinal silicon surface. Surprisingly, elongated clusters of the CuPc parallel to the step directions are formed even on the middle of the terraces well away from the step edges. The one-dimensional growth mode continues even after the full monolayer coverage on the substrate which results in strongly oriented growth mode of a thin film of CuPc on the vicinal silicon surfaces. 相似文献
1000.
H. Kim R.C.Y. Auyeung M. Ollinger G.P. Kushto Z.H. Kafafi A. Piqué 《Applied Physics A: Materials Science & Processing》2006,83(1):73-76
Low-temperature laser sintering has been successfully demonstrated to improve the overall conversion efficiency of dye-sensitized solar cells. Mesoporous TiO2 electrodes were prepared from a colloidal solution of TiO2 nanopowders by a laser direct-write technique and then sintered by a quasi-continuous-wave UV laser (λ=355 nm) for the fabrication of dye-sensitized solar cells. The overall conversion efficiency of the cells based on the laser-sintered TiO2 electrodes was double that of the devices with non-laser-treated TiO2 electrodes. This enhancement is attributed to both the removal of organic additives and the improved inter-nanoparticle electrical contacts induced by the laser-sintering process, which led to an increase in porosity and dye-absorption sites in the TiO2 electrodes. PACS 61.80.Ba; 61.46.+w; 73.22.-f; 84.60.Jt 相似文献