全文获取类型
收费全文 | 89篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 53篇 |
力学 | 1篇 |
数学 | 20篇 |
物理学 | 18篇 |
出版年
2022年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1867年 | 2篇 |
排序方式: 共有92条查询结果,搜索用时 171 毫秒
91.
Cisse L Djande A Capo-Chichi M Delatre F Saba A Tine A Aaron JJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(3):428-436
The solvent effects on the electronic absorption and fluorescence emission spectra of several coumarins derivatives, containing amino, N,N-dimethyl-amino, N,N-diethyl-amino, hydroxyl, methyl, carboxyl, or halogen substituents at the positions 7, 4, or 3, were investigated in eight solvents with various polarities. The first excited singlet-state dipole moments of these coumarins were determined by various solvatochromic methods, using the theoretical ground-state dipole moments which were calculated by the AM1 method. The first excited singlet-state dipole moment values were obtained by the Bakhshiev, Kawski-Chamma-Viallet, Lippert-Mataga, and Reichardt-Dimroth equations, and were compared to the ground-state dipole moments. In all cases, the dipole moments were found to be higher in the excited singlet-state than in the ground state because of the different electron densities in both states. The red-shifts of the absorption and fluorescence emission bands, observed for most compounds upon increasing the solvent polarity, indicated that the electronic transitions were of π-π* nature. 相似文献
92.
Adamou R Coly A Abdoulaye A Soumaila M Moussa I Ikhiri K Tine A 《Journal of fluorescence》2011,21(4):1409-1415
An analytical method based on the use of UV-irradiation to produce fluorescent derivatives from Etofenprox a non-fluorescent
pyrethroid insecticide is described. The impact of cetyltrimethylammonium chloride (CTAC) micellar medium on the Etofenprox
photochemically-induced fluorescence (PIF) is reported. Parameters influencing the sensitivity and repeatability of the PIF
method have been optimized. The alkaline medium (NaOH 6 × 10−2 M) + CTAC surfactant molecules (3.84 mg/ml) in acetonitrile is found to be very suitable for this pyrethroid insecticide
analysis in environment matrices. Linear dynamic range is established over more than two orders of magnitude. The limit of
detection is lower than 5 ng/ml. The method seems to be suitable for environmental matrices quality control. Application to
the analysis of spiked natural waters gave recoveries rate ranged from 94 to 104% and 107 to 115% respectively for river and
pound water. 相似文献