全文获取类型
收费全文 | 410篇 |
免费 | 16篇 |
国内免费 | 42篇 |
专业分类
化学 | 274篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 10篇 |
物理学 | 125篇 |
综合类 | 55篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 17篇 |
2012年 | 31篇 |
2011年 | 29篇 |
2010年 | 33篇 |
2009年 | 31篇 |
2008年 | 33篇 |
2007年 | 41篇 |
2006年 | 24篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有468条查询结果,搜索用时 15 毫秒
81.
82.
本文综合论述了在化学热处理过程中室温形变对间隙原子(C、N、B)扩散速度的影响.认为位错对扩散即有促进作用也有阻碍作用,其主要原因是温度的影响, 相似文献
83.
采用活性电沉积的方法共沉积硫化铁电极,并研究其在室温熔盐中的嵌锂行为.循环伏安及充放电结果表明,硫化铁电极在室温熔盐中具有较高的活性和稳定性.结果显示,硫化铁嵌锂过程分两步骤进行,第一步骤是一个可逆反应的过程,而第二步为不可逆过程. 相似文献
84.
Anne-Laure Revelli Fabrice MuteletJean-Noël Jaubert 《Journal of chromatography. A》2009,1216(23):4775-4786
Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55 K. The influence of gas–liquid and gas–solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model. 相似文献
85.
The detection of H2S was studied using several mediators in room temperature ionic liquids (RTILs) at a microelectrode. Each mediator was characterised voltammetrically, and H2S was added to observe if any mediation took place. A successful mediator was 3,5‐tert‐butyl‐obenzoquinone. Cyclic voltammetry was carried out in [C2mim][NTf2]. A reductive wave was observed and attributed to the two‐electron reduction of the mediator. No oxidative signal was observed. H2S was flowed through the system. Cyclic voltammograms showed a decrease in the reductive wave of the mediator and the onset of an oxidative signal due to the reaction between the mediator and H2S to form an adduct. This reaction is reversible and on purging the system with N2, the original reductive signal of the mediator was recovered. 相似文献
86.
A single electron transistor based on the ordered nanodot arrays was reported. The gold nanoparticles self-assembled in the ordered mesoporous silica thin films were used as the Coulomb islands. The Coulomb blockade and Coulomb oscillation are demonstrated at room temperature, and the SIMON simulations are consistent with the experimental results. 相似文献
87.
S. P. Perkins D. E. Shoosmith H. J. Coles 《Molecular Crystals and Liquid Crystals》2013,570(1):943-950
Abstract In this paper we present the results of mixing fluorinated and non-fluorinated organosiloxane materials based on ferroelectric and antiferroelectric low molar mass organosiloxane (LMMO) liquid crystals. None of the fluorinated materials exhibit a mesophase, however when mixed with the non-fluorinated analogues a ferroelectric phase is observed. We present the resultant phase diagrams together with the spontaneous polarisation curves of the mixtures. 相似文献
88.
Wen-Hui Bao Wei-Wei Ying Xu-Dong Xu Guo-Dong Zhou Xiao-Xiao Meng Wen-Ting Wei Yan-Yun Liu Qiang Li 《Tetrahedron letters》2019,60(1):55-58
Herein, metal-free radical Heck-type reaction of styrenes with sulfonyl hydrazides to synthesize vinyl sulfones is developed. The reaction is performed under economical TBAI/TBHP system on water in open air at room temperature, which proceeds through the radical addition to styrenes followed by hydrogen-abstraction. When compared to known approaches for the synthesis of vinyl sulfones from alkenes, this radical Heck-type strategy is practical, green and does not go through HI elimination process. Furthermore, this protocol can be expanded to the iodosulfonylation of alkynes for the synthesis of iodovinyl sulfones. 相似文献
89.
90.
Nano crystalline undoped (1Z) Zinc Oxide (ZnO) and 5, 10 and 15 Wt. % (1ZN, 2ZN and 3ZN) of Nickel doped ZnO based sensors were fabricated using the hydrothermal approach on Fluorine doped Tin Oxide (FTO) glass substrates. X-ray diffraction (XRD) analysis proved the hexagonal Wurtzite structure of ZnO. Parametric variations in terms of dislocation density, bond length, lattice parameters and micro strain with respect to dopant concentration were analysed. The prominent variations in the crystallite size, optical band gap and Photoluminescence peak ratio of devices fabricated was observed. The Field Emission Scanning Electron Microscope (FESEM) images showed a change in diameter and density of the nanorods. The effect of the operating temperature, concentration of ethanol and the different doping levels of sensitivity, response and recovery time were investigated. It was inferred that 376% of sensitivity with a very quick response and recovery time of <5 s and 10 s respectively at 150 °C of 3ZN sensor has better performance compared to other three sensors. Also 3ZN sensor showed improved sensitivity of 114%, even at room temperature with response and recovery time of 35 s and 45 s respectively. 相似文献