全文获取类型
收费全文 | 216篇 |
免费 | 4篇 |
专业分类
化学 | 141篇 |
力学 | 3篇 |
数学 | 20篇 |
物理学 | 56篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 38篇 |
2012年 | 3篇 |
2011年 | 15篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1961年 | 1篇 |
1951年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
61.
Hirata N Lagref JJ Palomares EJ Durrant JR Nazeeruddin MK Gratzel M Di Censo D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(3):595-602
A [Ru(dcbpy)(2)(NCS)(2)] dye has been chemically modified by the addition of a secondary electron donor moiety, N,N-(di-p-anisylamino)phenoxymethyl. Optical excitation of the modified dye adsorbed to nanocrystalline TiO(2) films shows a remarkably long-lived charge-separated state, with a decay half time of 0.7 s. Semiempirical calculations confirm that the HOMO of the modified dye molecule is localised on the electron donor group. The retardation of the recombination dynamics relative to the unmodified control dye is caused by the increase in the spatial separation of the HOMO orbital from the TiO(2) surface. The magnitude of the retardation is shown to be in agreement with that predicted from the non-adiabatic electron-tunnelling theory. 相似文献
62.
Abstract— Total diffuse reflectance spectra of air-dried surfaces of free and neutralized amino acid preparations before and after irradiation in vitro are reported. It was found that some free or neutralized amino acid surfaces underwent modification which resulted in changes in the diffuse reflectance spectra after U.V. exposure. It is suggested that these reflectance changes result from transformations in the side chains of the amino acids and that the transformations may differ from those occurring when amino acids in solution are irradiated. Histidine, cystine, hydroxyproline and some protein surfaces showed changes in reflectance of 330–400 nm light similar to those reported in skin after U.V. irradiation in viuo. 相似文献
63.
William J. Bland Reg. Davis James L.A. Durrant 《Journal of organometallic chemistry》1982,234(2):C20-C22
1/1 complex formation between benzene-d6 and [Cr(CO)3(η6-arene)] (arene = C6H5R (R = H, Me, OMe, Cl), C10H8) has been observed by PMR spectroscopy. The equilibrium constant in the case of arene =C6H6 confirms earlier chemical evidence that the [Cr(CO)3] unit exerts an electron-with-drawing effect upon aromatic rings which is approximately equal to that of the nitro group. 相似文献
64.
65.
66.
67.
Three-phase displacement experiments for a water-benzyl alcohol-decane system are simulated. Literature experimental three-phase relative permeabilities for the system are used to describe the relative permeabilities in the three-phase region for different three-phase relative permeability models. Saturation trajectories and elliptical regions are mapped in the three-phase region. Simulations are performed to model displacement experiments including breakthrough and the formation of multiple shocks. The model can be used to predict the results for other displacements. In an experiment where significant gravity segregation is present, the displacement is more accurately modeled by assuming a uniform initial condition than by using the actual vertical saturation and assuming no cross flow. It is shown how different residual saturation values can be measured in the laboratory depending on the initial saturation conditions in the core. The experimental residual saturations can be significantly different than the ‘theoretical’ or model values. 相似文献
68.
Successful implementation of change in a complex enterprise requires a shared understanding of system interdependency. Otherwise, the architecture of those changes risk the emergence of otherwise unforeseen obstacles. A fundamental element is understanding how the system responds to stimuli. Given the complexity of that system, no single model would adequately represent the totality of the enterprise. As such, we have employed a structured approach based on soft systems methodology and reference models to develop common pictures. These heuristic models act as anchor points for achieving a shared understanding and as a basis for the development of more detailed models. The approach has been applied to defence preparedness; a system containing many levels of inter-dependency, contested by a range of differing viewpoints, multilayered with decisions and activity at a number of levels, and often seeking to rapidly transition to solutions. We present some examples of distinct but inter-related reference models for defence preparedness. 相似文献
69.
Transient photovoltage and photocurrent measurements have been employed to determine the recombination and transport kinetics in operating dye-sensitized photovoltaic cells as a function of potential and temperature. Photocurrent transients have been taken at the open circuit potential, as opposed to the standard measurement at short circuit. Kinetic results have been used to calculate the activation energy as function of the Fermi level position in the TiO(2). In the calculation of activation energies, we have explicitly taken into account the temperature dependence of the offset between the electrolyte redox potential and the conduction band edge. This new method gives activation energies that decrease linearly as the Fermi level position moves toward the conduction band edge, as expected, but not found in previous studies. The results are consistent with the presence of a distribution of traps below the TiO(2) conduction band, the detrapping from which limits both the transport and the recombination of electrons. 相似文献
70.
Laia Francs Shababa Selim Sacha Corby Dongho Lee Camilo A. Mesa Ernest Pastor Kyoung-Shin Choi James R. Durrant 《Chemical science》2021,12(21):7442
In this work, spectroelectrochemical techniques are employed to analyse the catalytic water oxidation performance of a series of three nickel/iron oxyhydroxide electrocatalysts deposited on FTO and BiVO4, at neutral pH. Similar electrochemical water oxidation performance is observed for each of the FeOOH, Ni(Fe)OOH and FeOOHNiOOH electrocatalysts studied, which is found to result from a balance between degree of charge accumulation and rate of water oxidation. Once added onto BiVO4 photoanodes, a large enhancement in the water oxidation photoelectrochemical performance is observed in comparison to the un-modified BiVO4. To understand the origin of this enhancement, the films were evaluated through time-resolved optical spectroscopic techniques, allowing comparisons between electrochemical and photoelectrochemical water oxidation. For all three catalysts, fast hole transfer from BiVO4 to the catalyst is observed in the transient absorption data. Using operando photoinduced absorption measurements, we find that water oxidation is driven by oxidised states within the catalyst layer, following hole transfer from BiVO4. This charge transfer is correlated with a suppression of recombination losses which result in remarkably enhanced water oxidation performance relative to un-modified BiVO4. Moreover, despite similar electrocatalytic behaviour of all three electrocatalysts, we show that variations in water oxidation performance observed among the BiVO4/MOOH photoanodes stem from differences in photoelectrochemical and electrochemical charge accumulation in the catalyst layers. Under illumination, the amount of accumulated charge in the catalyst is driven by the injection of photogenerated holes from BiVO4, which is further affected by the recombination loss at the BiVO4/MOOH interface, and thus leads to deviations from their behaviour as standalone electrocatalysts.Elucidating the role of charge accumulation and reaction kinetics in governing the performance of Ni/Fe oxyhydroxides as electrocatalysts and as co-catalysts on BiVO4 photoanodes water oxidation. 相似文献