全文获取类型
收费全文 | 532篇 |
免费 | 45篇 |
国内免费 | 26篇 |
专业分类
化学 | 82篇 |
晶体学 | 4篇 |
力学 | 6篇 |
数学 | 135篇 |
物理学 | 376篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 48篇 |
2015年 | 18篇 |
2014年 | 29篇 |
2013年 | 27篇 |
2012年 | 44篇 |
2011年 | 50篇 |
2010年 | 54篇 |
2009年 | 38篇 |
2008年 | 30篇 |
2007年 | 32篇 |
2006年 | 32篇 |
2005年 | 19篇 |
2004年 | 17篇 |
2003年 | 13篇 |
2002年 | 4篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 1篇 |
排序方式: 共有603条查询结果,搜索用时 0 毫秒
1.
Surface modifications were performed on the indium tin oxide (ITO) substrates for polymer light-emitting devices, using the different treatment methods including solvent cleaning, hydrochloric acid treatment and oxygen plasma. The influence of modifications on the surface properties of ITO electrodes were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle, and four-point probe. The surface energies of the ITO substrates were also calculated from the measured contact angles. Experimental results demonstrate that the surface properties of the ITO substrates strongly depend on the modification methods, and oxygen plasma more effectively improves the ITO surface properties compared with the other treatments. Furthermore, the polymer light-emitting electrochemical cells (LECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized. It is observed that the surface modifications on ITO electrodes have a certain degree of influence upon the injection current, luminance and efficiency, but hardly upon the turn-on voltages of current injection and light emission which are close to the measured energy gap of electroluminescent polymer. Oxygen plasma treatment on the ITO electrode yields the better performance of the LECs, due to the improvement of interface formation and electrical contact of the ITO electrode with the polymer blend in the LECs. 相似文献
2.
Da-Zhi Li Li Gan Zi-Qiang Yang Zheng Liang Jia-Yin Li 《International Journal of Infrared and Millimeter Waves》1997,18(10):1885-1896
The dispersion characteristic of the plasma-loaded relativistic backward wave oscillator has been analyzed. The theoretical
model has been established and the numerical calculations accord with the experimental results, which provides some useful
suggestions on the designing of slow-wave structure of BWO. 相似文献
3.
碳纳米管电极超大容量离子电容器交流阻抗特性 总被引:18,自引:0,他引:18
采用碳纳米管作为超大容量离子电容器的电极材料,应用交流阻抗频谱法,研究了超大容量离子电容器的频率响应特性.结果表明,用碳纳米管块作电极,超大容量离子电容器在频率250 mHz以下出现“电荷饱和”;而用活性炭块作电极, 超大容量离子电容器在频率为100 mHz时仍未出现“电荷饱和”,这说明碳纳米管电极超大容量离子电容器的频率响应特性优于活性炭电极超大容量离子电容器的频率响应特性.上述两类超大容量离子电容器的阻抗谱中均出现倾角约为45°的直线段,其相位角均远小于理想电容器的相位角90°. 相似文献
4.
5.
《Chemical physics》1986,108(3):417-428
The molcules NSF, NSO−, NSCl, HNSF+, HNSO, CH3NSF+, CH3NSO are investigated at the SCF level and partly with inclusion of electron correlation effects. Equilibrium geometries and relative stabilities of isomers and conformers are reported. Structure constants and relative energies are discussed in connection with the molecular electronic structure as characterized by the results of population analyses. 相似文献
6.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1986,42(7):781-783
The electronic absorption spectra of 5-and 6-fluoroindoles, corresponding to the λ2850 Å system of indole, have been recorded in the vapour phase and analysed, assuming Cs symmetry for the molecules. The observed band system in both the molecules which lies in the region λ3100–2680 Å has been identified as a π* ← π transition corresponding to a 1A′ ← 1A′ transition. The i.r. spectra of these molecules have also been recorded and analysed and the results are used in the analyses of the electronic spectra. These show that there is not much change in the shape and very little change in size of either of these molecules in the excited electronic states. 相似文献
7.
8.
9.
Dunhua Hong Taisong Pan Dayu Feng Zhenlong Huang Feiyi Liao XiaoMei Li Yin Zhang Min Gao 《Journal of Sol-Gel Science and Technology》2014,71(3):464-469
(LaBa)Co2O5+δ (LBCO) thin films were successfully fabricated on Si (001) substrates by polymer-assisted deposition method. Microstructures were examined by X-ray diffraction technique, which confirmed the films were a single phase, pseudo cubic structure. The electrical transport properties of the films were investigated by the temperature dependence of films resistance, which suggested that LBCO films have typical semiconductor properties. After circle tests, the oxygen–hydrogen response rate did not show obvious variation in the specific temperature environment of 580 °C. This demonstrates that the LBCO thin films have a superior stability in both oxygen and hydrogen (6 % H2, 94 % N2) environment. Simultaneously, the drastic changes of films resistance (from ~106 to ~102 Ω) with the switch of redox (O2–H2) environment within such a short time (~2.2 s) indicated that LBCO films have an excellent oxygen sensitive property and extraordinary fast surface exchange rate. 相似文献
10.
《Journal of Energy Chemistry》2017,26(1):193-199
In this paper In_2O_3 nanoshells have been synthesized via a facile hydrothermal approach.The nanoshells can be completely cracked into pony-size nanocubes by annealing,which are then used as a support of Pt catalyst for methanol and ethanol electrocatalytic oxidation.The prepared In_2O_3 and supported Pt catalysts(Pt/In_2O_3) were characterized by X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),field effect scanning electron microscopy(FESEM),and transmission electron microscopy(TEM).Cyclic voltammetry(CV),linear sweep voltammetry(LSV),chronoamperometry and electrochemical impedance spectroscopy(EIS) were carried out,indicating the excellent catalytic performance for alcohol electrooxidation can be achieved on Pt/In_2O_3 nanocatalysts due to the multiple active sites,high conductivity and a mass of microchannels and micropores for reactant diffusions arising from 3D frame structures compared with that on the Pt/C catalysts. 相似文献