首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   493篇
  免费   28篇
化学   379篇
晶体学   7篇
力学   11篇
数学   9篇
物理学   115篇
  2023年   5篇
  2022年   6篇
  2021年   6篇
  2020年   10篇
  2019年   11篇
  2018年   4篇
  2017年   5篇
  2016年   18篇
  2015年   9篇
  2014年   16篇
  2013年   22篇
  2012年   21篇
  2011年   21篇
  2010年   13篇
  2009年   32篇
  2008年   25篇
  2007年   25篇
  2006年   35篇
  2005年   31篇
  2004年   32篇
  2003年   22篇
  2002年   15篇
  2001年   11篇
  2000年   8篇
  1999年   4篇
  1998年   6篇
  1996年   6篇
  1995年   5篇
  1994年   8篇
  1993年   6篇
  1992年   4篇
  1991年   9篇
  1990年   5篇
  1989年   6篇
  1988年   3篇
  1987年   4篇
  1986年   7篇
  1985年   2篇
  1984年   5篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1980年   7篇
  1978年   5篇
  1975年   1篇
  1974年   1篇
  1973年   4篇
  1972年   2篇
  1969年   1篇
  1966年   1篇
排序方式: 共有521条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
Synthesis of titanate nanotubes (TNTs) from sol–gel derived amorphous TiO2 thin films under moderate hydrothermal condition has been reported. TNTs from film possess a tubular morphology that is the same crystalline phase as one synthesized from TiO2 powder so far. TNTs obtained in this study are not entangled one another but oriented and isolated on the substrate. Growth of highly oriented TNTs is observed in micro grooves of amorphous TiO2 thin film. Their orientation is also maintained with the growth of TNTs.  相似文献   
35.
Novel tetra-cationic xanthene derivative (Flu) was synthesized. Its adsorption and photochemical behaviors on the clay surface were investigated. Fluorescence quantum yield (?f) and fluorescence lifetime were 0.50 and 2.9 ns for Flu/clay complex. ?f of Flu was enough high (>0.1) even at high density conditions (0.080 molecules nm−2). It is supposed that the strong interaction between clay and Flu by the ‘Size-Matching Effect’ realizes the highly emissive clay complexes at high density adsorption condition by a suppression of a molecular aggregation, which tends to decrease the photochemical activity.  相似文献   
36.
We study the temperature evolution of aluminum nanoparticles generated by femtosecond laser ablation with spatiotemporally resolved x-ray-absorption fine-structure spectroscopy. We successfully identify the nanoparticles based on the L-edge absorption fine structure of the ablation plume in combination with the dependence of the edge structure on the irradiation intensity and the expansion velocity of the plume. In particular, we show that the lattice temperature of the nanoparticles is estimated from the L-edge slope, and that its spatial dependence reflects the cooling of the nanoparticles during plume expansion. The results reveal that the emitted nanoparticles travel in a vacuum as a condensed liquid phase with a lattice temperature of about 2500 to 4200 K in the early stage of plume expansion.  相似文献   
37.
To introduce halogen‐bond interactions between a cation and an anion, a novel FeIII complex from iodine‐substituted ligands involving a paramagnetic nickel dithiolene anion was prepared and characterized. The compound exhibited the synergy between a spin‐crossover transition and a spin‐Peierls‐like singlet formation. The halogen‐bond interactions between the iodine and the sulfur atoms stabilized the paramagnetic state of π‐spins and played a crucial role in the synergistic magnetic transition between d‐ and π‐spins. In addition, the compound showed the light‐induced excited spin state trapping effect.  相似文献   
38.
The structure of palladium, platinum and zirconium in the liquid state has been studied by X-ray diffraction near the melting point. In all the cases the structure factor looks similar to those of liquid metals such as copper and silver in contrast to mercury, tin and bismuth which show the small hump or the large asymmetry of the first peak maximum in the structure factor. The atomic radial distribution function was evaluated from the structure factor and the interatomic distance and coordination number of each liquid metal were also obtained. The effective interionic potential was derived from the structural data obtained in this work using the Born-Green equation and applied to the estimation of self-diffusion coefficient and viscosity coefficient in these liquid metals by the kinetic theory of fluids.  相似文献   
39.
[structure: see text] Synthesis and fluorescence properties of pi-conjugated compounds having alternately an aromatic ring such as benzene, pyridine, and thiophene and an enediyne unit in the backbone are described.  相似文献   
40.
The observation of slow-wave sustained (SW) discharge in a whistler- or helicon-wave range of frequency is made using high-frequency and very-high-frequency bands of rf. The SW discharge occurs at an extremely low rf power and plasma density, which are lower than a capacitive-coupling discharge region.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号