全文获取类型
收费全文 | 256175篇 |
免费 | 12650篇 |
国内免费 | 3035篇 |
专业分类
化学 | 162283篇 |
晶体学 | 3623篇 |
力学 | 9339篇 |
综合类 | 58篇 |
数学 | 26076篇 |
物理学 | 70481篇 |
出版年
2021年 | 2236篇 |
2020年 | 3510篇 |
2019年 | 5037篇 |
2018年 | 4513篇 |
2017年 | 4004篇 |
2016年 | 7940篇 |
2015年 | 6123篇 |
2014年 | 7603篇 |
2013年 | 13804篇 |
2012年 | 10451篇 |
2011年 | 11253篇 |
2010年 | 9297篇 |
2009年 | 9108篇 |
2008年 | 10906篇 |
2007年 | 10266篇 |
2006年 | 9400篇 |
2005年 | 8800篇 |
2004年 | 7737篇 |
2003年 | 7044篇 |
2002年 | 7561篇 |
2001年 | 7378篇 |
2000年 | 6064篇 |
1999年 | 3999篇 |
1998年 | 3205篇 |
1997年 | 3209篇 |
1996年 | 3011篇 |
1995年 | 2465篇 |
1994年 | 2535篇 |
1993年 | 2541篇 |
1992年 | 2695篇 |
1991年 | 2714篇 |
1990年 | 2636篇 |
1989年 | 2593篇 |
1988年 | 2494篇 |
1987年 | 2469篇 |
1986年 | 2400篇 |
1985年 | 3077篇 |
1984年 | 3208篇 |
1983年 | 2577篇 |
1982年 | 2836篇 |
1981年 | 2708篇 |
1980年 | 2509篇 |
1979年 | 2722篇 |
1978年 | 2833篇 |
1977年 | 2859篇 |
1976年 | 2834篇 |
1975年 | 2688篇 |
1974年 | 2665篇 |
1973年 | 2810篇 |
1972年 | 1875篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
A. A. Solov’ev M. A. Pashina O. E. Lebedeva 《Russian Journal of Applied Chemistry》2007,80(2):275-278
The influence of inorganic salts on the kinetics of oxidation of 2,4-and 2,6-dinitrophenols by Fenton’s reagent, hydrogen peroxide, in the presence of iron(II) ions was studied. 相似文献
942.
Infrared difference spectroscopy has been used to study the association of p-nitrophenol (NP) with butyl acetate (BA) in CCl4 and in undiluted BA. It has been shown that in CCl4, an associate is formed, [NP·BA] ·BA (Ia), in which one molecule of BA is linked to the NP by a hydrogen bond, and the second BA molecule is linked to the H-complex NP·BA by outer-sphere (dipole-dipole) interaction. In undiluted BA with low concentrations of NP, (Ia) is formed; with high concentrations of NP, an associate [(NP)2BA] ·mBA is formed, in which two molecules of NP are bonded successively to each other and with a BA molecule; and the number of outer-sphere BA molecules may depend on the concentration of free BA molecules in the solutions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 593–599, March, 1991. 相似文献
943.
944.
945.
E. Beinrohr M. Németh P. Tsch?pel G. T?lg 《Fresenius' Journal of Analytical Chemistry》1992,344(3):93-99
Summary Flow-through electrochemical cells with porous working electrodes made of crushed reticulated vitreous carbon and plated with mercury were used for absolute analysis of trace amounts of lead by anodic stripping coulometry with collection (ASCWC) in a flow system. The role of mercury coating, flow rate and pH were investigated. The coulombic content of the collection peak corresponded to the theoretical values calculated by Faraday's law in a concentration range from about 10–9 to 10–6 mol/l. The relative error and the relative standard deviation was +0.15% and 0.8%, respectively for 2×10–6 mol/l analyte concentration. The absolute detection limit (3 s) was 0.1 ng of Pb, the linear response range 7×104.
One leave from: Department of Analytical Chemistry, Slovak Technical University, CS-812 37 Bratislava, Czechoslovakia 相似文献
946.
947.
E. S. Moskalenko M. Larsson K. F. Karlsson P. O. Holtz B. Monemar W. V. Schoenfeld P. M. Petroff 《Physics of the Solid State》2007,49(10):1995-1998
We report on low-temperature microphotoluminescence (μ-PL) measurements of InAs/GaAs quantum dots (QDs) exposed to a lateral
external electric field. It is demonstrated that the QDs’ PL signal could be increased severalfold by altering the external
and/or the internal electric field, which could be changed by an additional infrared laser. A model which accounts for a substantially
faster lateral transport of the photoexcited carriers achieved in an external electric field is employed to explain the observed
effects. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity
measured in our experiment—a finding which could be used to tailor the properties of QD-based optoelectronic applications.
The text was submitted by the authors in English. 相似文献
948.
N. B. Voznesensky E. V. Gavrilov A. P. Zhevlakov V. K. Kirillovskiĭ P. V. Orlov 《Technical Physics》2007,52(2):271-275
Methods and schemes to inspect the EUV mirror shape are developed on the basis of a point diffraction interferometer with computer processing of interferograms. A measurement accuracy to within 0.001 of a wavelength in the visual range is achieved. 相似文献
949.
The variation of the density functions on chaotic spheres in chaotic space-like Minkowski space time
A.E. El-Ahmady 《Chaos, solitons, and fractals》2007,31(5):1272-1278
In this article we introduce types of chaotic spheres in chaotic space-like Minkowski space time Mn+1. The variations of the density functions under the folding of these chaotic spheres are defined. The foldings restriction imposed on the density function are also discussed. The relations between the folding of geometry and pure chaotic manifolds are deduced. Some theorems concerning these relations are presented. 相似文献
950.