全文获取类型
收费全文 | 1374840篇 |
免费 | 25946篇 |
国内免费 | 7848篇 |
专业分类
化学 | 693255篇 |
晶体学 | 20126篇 |
力学 | 75021篇 |
综合类 | 105篇 |
数学 | 245887篇 |
物理学 | 374240篇 |
出版年
2021年 | 13598篇 |
2020年 | 16052篇 |
2019年 | 16251篇 |
2016年 | 27869篇 |
2015年 | 20992篇 |
2014年 | 30796篇 |
2013年 | 75049篇 |
2012年 | 40322篇 |
2011年 | 37522篇 |
2010年 | 37329篇 |
2009年 | 39324篇 |
2008年 | 36637篇 |
2007年 | 32067篇 |
2006年 | 39566篇 |
2005年 | 30751篇 |
2004年 | 32114篇 |
2003年 | 30096篇 |
2002年 | 31299篇 |
2001年 | 30315篇 |
2000年 | 26042篇 |
1999年 | 23209篇 |
1998年 | 21459篇 |
1997年 | 21349篇 |
1996年 | 21357篇 |
1995年 | 19388篇 |
1994年 | 18835篇 |
1993年 | 18373篇 |
1992年 | 18501篇 |
1991年 | 18753篇 |
1990年 | 17911篇 |
1989年 | 17940篇 |
1988年 | 17520篇 |
1987年 | 17411篇 |
1986年 | 16408篇 |
1985年 | 22841篇 |
1984年 | 24015篇 |
1983年 | 20156篇 |
1982年 | 21881篇 |
1981年 | 21055篇 |
1980年 | 20387篇 |
1979年 | 20600篇 |
1978年 | 21873篇 |
1977年 | 21454篇 |
1976年 | 21216篇 |
1975年 | 19930篇 |
1974年 | 19624篇 |
1973年 | 20084篇 |
1972年 | 14543篇 |
1968年 | 12351篇 |
1967年 | 12676篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
851.
852.
The influence of the well width fluctuations on the dependence of the binding energy of excitonic complexes in quantum wells is studied by using the path-integral Monte-Carlo technique. The results are compared with available experimental data and a good agreement is found.Postdoctoral researcher of FWO-Vlaanderen 相似文献
853.
The composite comprised of zinc oxide quantum dots and poly(amic acid) (PAAc) was prepared and studied by X-rays diffraction, X-ray photoelectron spectroscopy, light scattering, UV absorbance and UV fluorescence. The UV absorbance of the ZnO/PAAc composite was found to be much larger than that of its components taken separately. The fluorescence of the ZnO/PAAc composite was found to be shifted to longer wavelengthes in comparison with pure ZnO. The presence of the dopant dodecylbenzenesulfonic acid was found to affect the observed fluorescence. 相似文献
854.
A short and highly efficient approach was applied for the total synthesis of the gypsy moth sex pheromone (+)-disparlure and its enantiomer from isopropylidene D- and L-erythrose, using a common strategy. 相似文献
855.
856.
C. Mattea N. Fatkullin E. Fischer U. Beginn E. Anoardo M. Kroutieva R. Kimmich 《Applied magnetic resonance》2004,27(3-4):371-381
Linear polyethylene oxides with molecular weightsM w of 1665 and 10170 confined in pores with variable diameters in a solid methacrylate matrix were studied by proton field-cycling nuclear magnetic resonance relaxometry. The pore diameter was varied in the range of 9–57 nm. In all cases, the spin-lattice relaxation time shows a frequency dependence close toT 1∞ v3/4 in the range ofv=3·10?1-2·101 MHz as predicted by the tube-reptation model. This protonT 1 dispersion essentially reproduces that found in a previous deuteron study (R. Kimmich, R.-O. Seitter, U. Beginn, M. Möller, N. Fatkullin: Chem. Phys. Lett. 307, 147, 1999). As a feature particularly characteristic for reptation, this finding suggests that reptation is the dominating chain dynamics mechanism under pore confinement in the corresponding time range. The absolute values of the spin-lattice relaxation times indicate that the diameter of the effective tubes in which reptation occurs is much smaller than the pore diameters on the time scale of spin-lattice relaxation experimens. An estimation leads to a valued *~0.5 nm. The impenetrability of the solid pore walls, the uncrossability of polymer chains (“excluded volume”) and the low value of the compressibility in polymer melts create the “corset effect” which reduces the lateral motions of polymer chains to a microscopic scale of only a few tenths of a nanometer. 相似文献
857.
J. Stankowski 《Applied magnetic resonance》2004,27(1-2):251-258
Microwave nonresonant dissipation observed around zero field makes a powerful method in characterizing superconducting state (to determineT C,H C1,H CJ parameters). This review shows several successful applications of magnetically modulated microwave absorption (MMMA). MMMA enables to study MgB2 superconducting nanoregions embedded in the Mg host structure. Application of MMMA to study intercalation of fullerence enabled the observation of a new superconducting phase. The pressure effect dT C/dp has been studied below the percolation threshold in YBaCuO/PST composites. The local temperature of the Josephson junction measured by the MMMA technique showed that a granular superconductor consists of two phases: host phase and Josephson junction system. MMMA has been applied lately to separate the giant magnetoresistance from the magnetization effect in differential hysteresis loops. 相似文献
858.
F. Meyer 《Fresenius' Journal of Analytical Chemistry》1885,24(1):617
Ohne Zusammenfassung 相似文献
859.
F. Klein 《Fresenius' Journal of Analytical Chemistry》1885,24(1):379-388
Ohne ZusammenfassungNieder-Ingelheim, 3. Mai 1885. 相似文献
860.
A method for preparing sulfate-oxalate chromium-plating solutions by reducing Cr(VI) from industrial chromium-plating electrolytes to Cr(III) with a Na2SO3 solution is proposed. 相似文献