全文获取类型
收费全文 | 86篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 28篇 |
力学 | 2篇 |
数学 | 30篇 |
物理学 | 29篇 |
出版年
2023年 | 1篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 31 毫秒
21.
Belkacem Belaabed Jean Luc Wojkiewicz Saad Lamouri Noureddine El Kamchi Nathalie Redon 《先进技术聚合物》2012,23(8):1194-1201
Composites based on conductive organic/inorganic fillers dispersed in insulating matrix have been widely investigated because of their widespread applications such as electromagnetic shielding, electrostatic discharge, and sensors. In this context, novel composite materials based on epoxy resin matrix charged with polyaniline (PANI)‐doped para‐toluene sulfonic acid were elaborated. Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy were used to check the structure and the morphology of the samples. Viscoelastic behavior and thermal stability of the composites were explored by dynamic mechanical thermal analysis and thermogravimetric analysis. It was shown that the PANI particles exhibited a partial crystalline structure and were homogeneously dispersed in epoxy matrix. Consequently, this structure affected the thermal stability and viscoelastic properties of the composites. Furthermore, the dielectric and electrical properties were investigated up to 1 MHz. Measurements of dielectric properties revealed that with loading fillers in matrix, the dielectric parameters increased to high values at low frequency then decreased at values around 40 and 32 of real and imaginary parts, respectively, at 1 MHz with 15% of PANI content. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
22.
Belkacem Benmerad Achoura Guehria‐Laïdoudi Grald Bernardinelli Fadila Balegroune 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):321-323
The title compound, [La2(C3H2O4)3(H2O)4]·H2O, forms a layer‐type polymeric structure. The layers, which contain infinite puckered four‐membered La—O—La—O rings in a pseudo‐ternary symmetry, are formed by the lanthanum and one independent malonate group. They are interconnected by the second independent malonate group, giving a three‐dimensional framework in which wide channels accommodate one disordered water molecule of crystallization. The La atom lies on a twofold axis and is ten‐coordinated by eight O atoms from carboxylate groups and two water molecules. One malonate group is monodentate and triply bridging chelating, whilst the other is doubly monodentate. The extensive network of hydrogen bonds and bridge bonds observed in this structure enhances the structural stability. Despite some identical subfeatures, this structure is quite different from that observed in [La2(C3H2O4)3(H2O)3]·2H2O. 相似文献
23.
Belkacem Bendiffalah 《Comptes Rendus Mathematique》2004,339(6):387-390
We construct a long exact sequence where the extensions modules of a triangular algebra are involved with extension modules of its diagonal algebras. This holds in two cases: either its bimodule is right-projective or it is left-flat. This completes a result of Palmér and Roos about the global dimension of triangular algebras. To cite this article: B. Bendiffalah, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
24.
Naziha Ladjal Belkacem Zidelkheir Smail Terchi 《Journal of Thermal Analysis and Calorimetry》2018,133(2):881-891
The thermal degradation of thermally cured vinyl ester resin systems is studied for different heating rates. The kinetic triplets, the activation energy, pre-exponential factor and the reaction model f(α) for the different reaction extent of conversions (α) are estimated using advanced isoconversional methods. Although the thermal degradation curves show the degradation occurs as a single stage, the kinetic parameters suggest the otherwise. The activation energy remains constant for α?=?0.3–0.575 but varies during the initial and final stages of conversion. Similarly, the pre-exponential factor shows considerable variation between the lower and higher reaction extent (α) values. This shows the complexity in the reaction. The probable reaction mechanism that the degradation follows has been explained. The complexity of the thermal degradation and the changes in reaction model f(α) over different reaction extent has been related. The appropriate working temperature for different thermal lifetime of the cured vinyl ester resin system for the failure of conversion α?=?0.2 has been predicted under the nitrogen atmosphere. 相似文献
25.
In this paper, we consider a Timoshenko system with a delay term in the feedback and prove a stability result. The beam is clamped at the endpoints and has, in addition to an internal damping, a feedback with a delay.Under an appropriate assumption on the weights of the two feedbacks, we prove the well-posedness of the system and establish an exponential decay result for the case of equal-speed wave propagation. 相似文献
26.
Jean-Jacques Aaron Belkacem Laassis M. Carmen Mahedro Arsenio Muñoz de la Peña F. Salinas 《Journal of inclusion phenomena and macrocyclic chemistry》1994,18(1):69-79
The photo-oxidation reaction of phenothiazine has been studied in the presence of-cyclodextrin (-CD) and 2-hydroxypropyl-cyclodextrin (HP -CD). The influence of these organized media on the formation of the oxidation photoproduct upon UV irradiation has been investigated. Phenothiazine forms an inclusion complex with the cyclodextrins. The stoichiometry and formation constant of the complex formed with 2-hydroxypropyl -CD have been calculated using the changes of the fluorescence emission signal and of the absorbance of the drug upon inclusion. An increase of the fluorescence intensity of the photogenerated product is attained when it becomes included inside the cyclodextrin cavity. 相似文献
27.
Gael Colomines Belkacem Otazaghine Cyrille Boyer Sophie Monge Jean‐Jacques Robin 《Journal of polymer science. Part A, Polymer chemistry》2008,46(2):433-443
Valorization of poly(ethylene terephthalate) (PET) waste has been achieved using glycolysis. The resulting diols were employed for the synthesis of triblock copolymers by atom transfer radical polymerization using copper (I) bromide and (1,1,4,7,10,10)‐hexamethyltriethylenetetramine as catalyst system. Macroinitiator was obtained after depolymerization of PET waste followed by functionalization of the obtained glycolysate with 2‐bromoisobutyrate bromide. Polymerization of styrene (S) and glycidyl methacrylate (GMA) has been achieved leading to PS‐b‐PETG‐b‐PS and (PS‐stat‐PGMA)‐b‐PETG‐b‐(PS‐stat‐PGMA) triblock copolymers. Best results were obtained at 100 °C. At this temperature, termination reaction were negligible and the measured number‐average molar mass of the product increased linearly with monomer conversion in agreement with the theoretical Mn with low polydispersity products achieved. Polymers were also characterized by 1H NMR. This work presents a original valorization of PET waste as (PS‐stat‐PGMA)‐b‐PETG‐b‐(PS‐stat‐PGMA) copolymer could be used as heat curable coatings. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 433–443, 2008 相似文献
28.
29.
Belkacem Benmerad Achoura Guehria‐Laidoudi Fadila Balegroune Henrik Birkedal Gervais Chapuis 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):789-792
The structure of the title compound, [La(C5H6O4)(C5H7O4)‐(H2O)]·H2O, consists of dense layers formed by chains of one‐edge‐sharing LaO9(H2O) polyhedra, linked together by the glutarate ligand. The three‐dimensional polymeric structure, built up through connection of these layers by the hydrogen glutarate ligand, exhibits cavities accommodating a guest water molecule. The lanthanum ion is tenfold coordinated by four glutarates, acting as bridging–chelating carboxylate groups, by three hydrogen glutarates, three times monodentate, and by one water molecule. Its coordination polyhedron is highly distorted and intermediate between a bicapped dodecahedron and a tetracapped trigonal prism. Hydrogen bonding links the two water molecules and the framework built up from this polynuclear coordination polymer. A very short hydrogen bond, D?A = 2.484 (3) Å, links the protonated with the deprotonated acid groups in the hydrogen glutarate. 相似文献
30.
In this work, we have prepared electrochemically and studied a composite materials based on an organic conducting polymer, polyaniline (PANI), in which inorganic semiconductor titanium dioxide (TiO2) particles were incorporated with different concentrations. The polyaniline/titanium dioxide composite material which had been deposited by cyclic voltammetry on substrates of indium tin oxide was then characterized. The cyclic voltammogram showed one redox couple characteristic of the oxidation and reduction states of the produced composite material. The impedance spectroscopy study showed that the resistance of the film increases with the TiO2 cocntent incorporated in the polymer. The incorporation of TiO2 in PANI covering the surfaces was confirmed by the scanning electron microscopy and the energy dispersive X-ray analysis. The morphological analysis of the film surfaces showed that the TiO2 nanoparticle increased the roughness. These observations allow to consider a new approach to improve the physicochemical properties of the interface between the organic and inorganic material. The I–V characteristics of PANI+TiO2 heterostructure diode showed the nonlinear nature of the I–V curve of PANI+TiO2 heterostructure device. 相似文献