全文获取类型
收费全文 | 89篇 |
免费 | 1篇 |
专业分类
化学 | 37篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 25篇 |
物理学 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有90条查询结果,搜索用时 31 毫秒
21.
Mosbah Habib Chahdoura Hassiba Mannai Asma Snoussi Mejdi Aouadi Kaïss Abreu Rui M. V. Bouslama Ali Achour Lotfi Selmi Boulbaba 《Applied biochemistry and biotechnology》2019,187(3):1113-1130
Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various... 相似文献
22.
The bending responses of porous functionally graded (FG) thick rectangular plates are investigated according to a high-order shear deformation theory. Both the effect of shear strain and normal deformation are included in the present theory and so it does not need any shear correction factor. The equilibrium equations according to the porous FG plates are derived. The solution to the problem is derived by using Navier's technique. Numerical results have been reported and compared with those available in the open literature for non-porous plates. The effects of the exponent graded and porosity factors are investigated. 相似文献
23.
Amel?Ben Slimane Mohamed?M.?ChehimiEmail author Marie-Josèphe?Vaulay 《Colloid and polymer science》2004,282(4):314-323
Polypyrrole (PPy)-coated poly(vinyl chloride) (PVC) powder particles were prepared by the in situ chemical polymerisation of pyrrole in aqueous solutions in the presence of PVC powder particles. The PVC particles in suspension served as a hydrophobic substrate for the in situ polymerisation of pyrrole using iron chloride as the oxidising agent and sodium p-toluene sulfonate. In these conditions, tosylate-doped PPy (PPyTS) was obtained and chlorides were inserted as minor codoping species. In some cases, the pyrrole was polymerised after incubating the PVC particles with poly(N-vinyl pyrrolidone). Scanning electron microscope (SEM) micrographs showed that the PVC particles retained their initial, quasispherical shape after coating by PPy. At low magnification, the coated PVC particles appeared smooth, but at high magnification, they exhibited a decoration by elementary nanoparticles of about 200-nm size due to PPy bulk powder grains. Elemental analysis indicated a mass loading of PPy in the range 1–58% w/w. Specific surface analysis by X-ray photoelectron spectroscopy (XPS) resulted in the spectra of the PPy-coated PVC particles resembling those of bulk powder PPyTS even for low PPy mass loading. The surface fraction of PPy repeat units was found to vary in the 55–91% range. This result is consistent with the SEM observation of the PPy nanoparticles at the surface of PVC powder grains. However, despite the important loading of PPy, the XPS estimation of the overlayer thickness is in favour of a patchy coating rather than continuous coatings of PPy. 相似文献
24.
Corma A García H Moussaif A Sabater MJ Zniber R Redouane A 《Chemical communications (Cambridge, England)》2002,(10):1058-1059
Two solid catalysts in which a chiral copper(II) bisoxazoline has been covalently anchored on silica and MCM-41 have been prepared; the solids are enantioselective catalysts (up to 92% ee) for the Friedel-Crafts hydroxyalkylation of 1,3-dimethoxybenzene with 3,3,3-trifluoropyruvate. 相似文献
25.
26.
We characterize pointwise directional regularity by highly oriented multi-scaled wavelet coefficients. 相似文献
27.
Many natural mathematical objects, as well as many multi-dimensional signals and images from real physical problems, need to distinguish local directional behaviors (for tracking contours in image processing for example). Using some results of Jaffard and Triebel, we obtain criteria of directional and anisotropic regularities by decay conditions on Triebel anisotropic wavelet coefficients (resp. wavelet leaders). 相似文献
28.
29.
Dr. Julien Lieffrig Dr. Olivier Jeannin Arkadiusz Frąckowiak Dr. Iwona Olejniczak Roman Świetlik Dr. Slimane Dahaoui Dr. Emmanuel Aubert Prof. Dr. Enrique Espinosa Dr. Pascale Auban‐Senzier Dr. Marc Fourmigué 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14804-14813
Charge‐assisted halogen bonding is unambiguously revealed from structural and electronic investigations of a series of isostructural charge‐transfer complexes derived from iodinated tetrathiafulvalene and tetracyanoquinodimethane derivatives, (EDT‐TTFI2)2(TCNQFn), n=0–2, which exhibit variable degrees of ionicity. The iodinated tetrathiafulvalene derivative, EDT‐TTFI2, associates with tetracyanoquinodimethane (TCNQ) and its derivatives of increasing reduction potential (TCNQF, TCNQF2) through highly directional C? I???N≡C halogen‐bond interactions. With the less oxidizing TCNQ acceptor, a neutral and insulating charge‐transfer complex is isolated whereas with the more oxidizing TCNQF2 acceptor, an ionic, highly conducting charge‐transfer salt is found, both of 2:1 stoichiometry and isostructural with the intermediate TCNQF complex, in which a neutral–ionic conversion takes place upon cooling. A correlation between the degree of charge transfer and the C? I???N≡C halogen‐bond strength is established from the comparison of the structures of the three isostructural complexes at temperatures from 300 to 20 K, thus demonstrating the importance of electrostatics in the halogen‐bonding interaction. The neutral–ionic conversion in (EDT‐TTFI2)2(TCNQF) is further investigated through the temperature dependence of its magnetic susceptibility and the stretching modes of the C≡N groups. 相似文献
30.
Sébastien Aupetit Nicolas Monmarché Mohamed Slimane 《Journal of Mathematical Modelling and Algorithms》2007,6(2):175-193
In this work we consider the problem of Hidden Markov Models (HMM) training. This problem can be considered as a global optimization
problem and we focus our study on the Particle Swarm Optimization (PSO) algorithm. To take advantage of the search strategy
adopted by PSO, we need to modify the HMM's search space. Moreover, we introduce a local search technique from the field of
HMMs and that is known as the Baum–Welch algorithm. A parameter study is then presented to evaluate the importance of several
parameters of PSO on artificial data and natural data extracted from images. 相似文献