全文获取类型
收费全文 | 197篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
化学 | 141篇 |
晶体学 | 10篇 |
数学 | 1篇 |
物理学 | 51篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 6篇 |
2011年 | 20篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 20篇 |
2007年 | 6篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有203条查询结果,搜索用时 0 毫秒
21.
Soda-lime-silicate glasses doped with different rare-earth oxides (La2O3, CeO2, Nd2O3, Gd2O3 and Y2O3) of 1 mol% content were prepared with the traditional melting-quenching methods. In order to reveal the effects of rare-earth elements on the behavior of soda-lime-silicate glass, the structure of soda-lime-silicate glasses doped with different rare-earth oxides were determined with Fourier transform infrared spectrometer using the KBr method, and viscosity of glass melts were measured by the rotating crucible viscometer, the melting temperature of the studied glasses were derived on the basis of Arrhenius Equation, moreover the density, bending strength and molar volume were measured and calculated. The effect of rare-earth dopants on the structure of soda-lime-silicate was analyzed by a shift of peak position and variation in the full-width at half-maximum. The effect of doping rare-earth oxides into glass on the viscosity, density and bending strength was interpreted by changing in structure of soda-lime-silicate glasses doped with rare-earth oxides. 相似文献
22.
(9−x)CaO·xMgO·15Na2O·60SiO2·16CaF2(x=0, 2, 4, 6, and 9) oxyfluoride glasses were prepared. Utilizing the Raman scattering technique together with 29Si and 19F MAS NMR, the effect of alkaline metal oxides on the Q species of glass was characterized. Raman results show that as magnesia is added at the expense of calcium oxide, the disproportional reaction Q3→Q4+Q2 (Qn is a SiO4 tetrahedron with n bridging oxygens) prompted due to the high ionic field strength of magnesia, magnesium oxide entered into the silicate network as tetrahedral MgO4, and removed other modifying ions for charge compensation. This reaction was confirmed by 29Si MAS NMR. 19F MAS NMR results show that fluorine exists in the form of mixed calcium sodium fluoride species in all glasses and no Si–F bonds were formed. As CaO is gradually replaced by MgO (x=6, 9), a proportion of the magnesium ions combines with fluorine to form the MgF+ species. Meanwhile, some part of Na+ ions complex F− in the form of F–Na(6). 相似文献
23.
24.
25.
Hans E. Miltner Christophe Block Guy Van Assche Kurt Van Durme Bogdan Bogdanov 《European Polymer Journal》2010,46(5):984-996
A comprehensive overview of available methods for assessing nanofiller dispersion is presented for a wide range of layered silicate-based poly(ε-caprolactone) (PCL) nanocomposites. Focusing on their respective strengths and weaknesses, rheological, mechanical and thermal characterization approaches are evaluated in direct relation to morphological information. Pronounced changes in the rheological and mechanical properties of the materials are only observed for nanocomposites displaying the highest nanofiller dispersion levels, as confirmed by an innovative and highly reliable thermal analysis approach based on quasi-isothermal crystallization. As such, the data obtained from the different methods also allow a detailed investigation of the crucial factors affecting nanofiller dispersion, evidencing the importance of specific matrix/filler interactions and the need for proper melt processing conditions when targeting significant property enhancements. Finally, the wide potential of the developed methodologies for the characterization of polymeric nanocomposites in general is illustrated by an extension to carbon nanotube-based PCL composites, unambiguously demonstrating their complementarity and broad applicability. 相似文献
26.
27.
28.
29.
Christian Bocker Francisco Muñoz Christian Rüssel 《Journal of solid state chemistry》2011,184(2):405-410
The transparent glass-ceramics obtained in the silicate system Na2O/K2O/SiO2/BaF2 show homogeneously dispersed BaF2 nano crystals with a narrow size distribution. The X-ray diffraction and the nuclear magnetic resonance spectroscopy were applied to glasses and the respective glass-ceramics in order to clarify the crystallization mechanism and the role of fluorine during crystallization. With an increasing annealing time, the concentration and also the number of crystals remain approximately constant. With an increasing annealing temperature, the crystalline fraction increases until a saturation limit is reached, while the number of crystals decreases and the size of the crystals increases. Fluoride in the glassy network occurs as Al-F-Ba, Al-F-Na and also as Ba-F structures. The latter are transformed into crystalline BaF2 and fluoride is removed from the Al-F-Ba/Na bonds. However, some fluorine is still present in the glassy phase after the crystallization. 相似文献
30.
白光电致发光二极管(LED)是固体照明的重要光源.荧光体转换是获取白光LED的主要途径之一.当前,转换用荧光体的研究在发光材料领域中最活跃.本文对近年来白光LED用发光材料新体系的研究进展作了评述. 相似文献