全文获取类型
收费全文 | 216篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
化学 | 115篇 |
晶体学 | 6篇 |
力学 | 15篇 |
数学 | 60篇 |
物理学 | 29篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 18篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 13篇 |
2005年 | 2篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有225条查询结果,搜索用时 15 毫秒
101.
We study global regularity properties of invariant measures associated with second order differential operators in RN. Under suitable conditions, we prove global boundedness of the density, Sobolev regularity, a Harnack inequality and pointwise upper and lower bounds. 相似文献
102.
Secondary benzylic or allylic trimethylsilyl ethers are oxidized at room temperature to the corresponding ketones in good yields using aqueous 70% t-BuOOH and catalytic amounts of a mixture of Ph3SiOH and CrO3. 相似文献
103.
Djilani Imene Nouar Leila Madi Fatiha Haiahem Sakina Bouhadiba Abdelaziz Khatmi DjamelEddine 《Comptes Rendus Chimie》2013,16(8):696-703
The structural aspects for the complexation of ortho-anisidine (O-AN)/β-cyclodextrin were explored by using PM6, density function theory B3LYP/6-31G*, M05-2X/6-31G*, B3PW91/6-31G*, MPW1PW91/6-31G*, HF/6-31G* methods and several combinations of ONIOM2 hybrid calculations. Calculations were performed upon the inclusion complexation of β-cyclodextrin (β-CD) with neutral (O-AN1) and cationic (O-AN2) species of ortho-anisidine. The obtained results with PM6 method clearly indicate that the formed complexes are energetically favored, the complex of O-AN2/β-CD in B orientation is significantly more favorable than the others energetically. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital (NBO) analysis, employed to quantify the donor–acceptor interactions between ortho-anisidine and β-CD. 相似文献
104.
Bouhadiba Abdelaziz Nouar Leila Haiahem Sakina Djilani Imene Madi Fatiha Khatmi DjamelEddine 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):455-462
The inclusion complex of β-cyclodextrin (β-CD) and diphenylamine (DPA) was investigated by using PM3MM, DFT, HF and ONIOM2 methods. The most stable structure was obtained at the optimum position and angle. The results indicate that the inclusion complex formed by DPA entering into the cavity of β-CD from its wide side (the secondary hydroxyl group side) is more stable than that formed by DPA entering into the cavity of β-CD from its narrow side (the primary hydroxyl group side). The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital (NBO) analysis, employed to quantify the donor–acceptor interactions between diphenylamine and β-CD. A study of these complexes in solution was carried out using the CPCM model to examine the influence of solvation on the stability of the diphenylamine β-CD complex. 相似文献
105.
Abdelaziz Foul 《Operations Research Letters》2006,34(3):264-268
Center problems or minimax facility location problems are among the most active research areas in location theory. In this paper, we find the best unique location for a facility in the plane such that the maximum expected weighted distance to all random demand points is minimized. 相似文献
106.
A simple theoretical model is proposed in order to represent gas–liquid slug flows in inclined ducts of arbitrary shape. To cite this article: A. Dyment, A. Boudlal, C. R. Mecanique 332 (2004). 相似文献
107.
Koczkur KM Hamed EM Hesp CR Houmam A 《Chemical communications (Cambridge, England)》2011,47(44):12128-12130
The reduction of N-(p-fluorobenzenesulfonyl)phthalimide on polycrystalline gold and Au(111) was studied. Our key finding is the decomposition of the compound on the surface, leaving only sulfur behind. This was supported by X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and scanning tunneling microscopy (STM). The modification leads to observation by STM of well-known as well as new phases for the S modified Au(111) surface. 相似文献
108.
Houmam A Muhammad H Chahma M Koczkur K Thomas DF 《Chemical communications (Cambridge, England)》2011,47(25):7095-7097
4-Nitrophenyl sulfenyl chloride was used as a new precursor for the formation of densely packed aromatic SAMs on gold. The adsorption involves the reductive dissociation of the S-Cl bond. A well-ordered row structure corresponding to a √3 × 4 phase with a molecular area of 27.8 ?(2) is obtained. 相似文献
109.
El Bouzidi L Abbad A Fattarsi K Hassani L Leach D Markouk M Legendre L Bekkouche K 《Natural product communications》2011,6(10):1491-1494
The chemical composition and anticandidal properties of the essential oil of Moroccan Cotula cinerea aerial parts have been examined. GC-MS data were used to identify 24 constituents. Oxygenated monoterpenes constituted the main fraction with trans-thujone (41.4%), cis-verbenyl acetate (24.7%), 1,8-cineole (8.2%) and camphor (5.5%) as the major components. The anticandidal activity of the essential oil was evaluated using a panel of human pathogenic fungi (Candida albicans CCMM L4 and CCMM L5, C. krusei CCMM L10, C. glabrata CCMM L7 and C. parapsilosis CCMM L18). The oil showed high anticandidal activity against all investigated strains with minimal inhibitory concentrations of 3.2 to 4.7 mg/mL depending on the tested yeast and 5.9 mg/mL as a minimal candidicidal concentration value. These findings add significant information to the pharmacological activity of Cotula cinerea essential oil, which may present a good alternative to antibiotics for the treatment of resistant strains of Candida. 相似文献
110.
We introduce multiple Dedekind–Rademacher sums, in terms of values of Bernoulli functions, that generalize the classical Dedekind–Rademacher sums. The aim of this paper is to give and prove a reciprocity law for these sums. The main theorem presented in this paper contains all previous results in the literature about Dedekind–Rademacher sums. 相似文献