全文获取类型
收费全文 | 151篇 |
免费 | 0篇 |
专业分类
化学 | 90篇 |
力学 | 10篇 |
数学 | 37篇 |
物理学 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 11篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有151条查询结果,搜索用时 18 毫秒
1.
Mohamed El Guendouzi Abderrahim Dinane Abdelfetah Mounir 《Journal of solution chemistry》2002,31(2):119-129
The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg– 1 for different ionic-strength fractions y of NH4Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions. 相似文献
2.
Abdelfetah Mounir Mohamed El Guendouzi Abderrahim Dinane 《Journal of solution chemistry》2002,31(10):793-799
Ternary aqueous solutions of MgSO4 and K2SO4 have been studied by the hygrometric method at 25°C. The relative humidity of this system is measured at total molalities from 0.35 mol-kg–1 to about saturation for three ionic-strength fractions (y = 0.25, 0.50, and 0.80 of MgSO4. The data allow calculation of water activities and osmotic coefficients. From these measurements, the Pitzer ionic mixing parameters are determined and used to predict the solute activity coefficients in the mixture. The results are used to calculate the excess Gibbs energy at total molalities for ionic-strength fraction y. 相似文献
3.
M. Smadhi R. Abderrahim 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2229-2232
The condensation of hexamethylphosphorotriamide and bis-(dimethylamino) methylphosphonate with amidrazones 1 constitutes a new route to the synthesis of 1,2,4,3-triazaphosphole-3-oxide derivatives 3. Structures of all the synthesized compounds have been established by NMR (1H, 13C, 31P) and IR spectroscopy, as well as by elemental analysis and MS spectral data for some products. 相似文献
4.
Tanguy Jousselin-Oba Masashi Mamada Karen Wright Jrome Marrot Chihaya Adachi Abderrahim Yassar Michel Frigoli 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202112794
We report the synthesis and optoelectronic properties of TIPS-peri-pentacenopentacene ( TIPS-PPP ), a vertical extension of TIPS-pentacene ( TIPS-PEN ) and a low-band-gap material with remarkable stability. We found the synthetic conditions to avoid the competition between 1,2- and 1,4-addition of lithium acetylide on the large aromatic dione. The high stability of TIPS-PPP is due to the peri-fusion which increases the aromaticity by generating two localized aromatic sextets that are flanked with 2 diene fragments, similar to two fused-anthracenes. Like TIPS-PEN , TIPS-PPP shows the archetypal 2D brickwall motif in crystals with a larger transfer integral and smaller reorganization energy. The high mobility of up to 1 cm2 V?1 s?1 was obtained in an organic field-effect transistor fabricated by a wet process. Also, TIPS-PPP was used as a near-infrared (NIR) emitter for NIR organic-light-emitting-diode devices resulting in a high external quantum efficiency at 800 nm. 相似文献
5.
Begaa Samir Messaoudi Mohammed Ouanezar Abdelkader Hamidatou Lylia Malki Abderrahim 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):1107-1112
Journal of Radioanalytical and Nuclear Chemistry - The objectives of this research were to study the elemental concentrations of Mentha spicata L., using a sensitive nuclear analytical technique... 相似文献
6.
Serdar Serdas Alexander Schwarz Jörg Schröder Stefan Turek Abderrahim Ouazzi Masoud Nickaeen 《PAMM》2014,14(1):623-624
In this contribution we present the least-squares finite element method (LSFEM) for the incompressible Navier-Stokes equations. In detail, we consider a non-Newtonian fluid flow, which is described by a power-law model, see [1]. The second-order problem is reformulated by introducing a first-order div-grad system consisting of the equilibrium condition, the incompressibility condition and the constitutive equation, which are written in residual forms, see [2]. Here, higher-order finite elements which are an important aspect regarding accuracy for the present formulation are investigated. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
Guyon F Hameau A Khatyr A Knorr M Amrouche H Fortin D Harvey PD Strohmann C Ndiaye AL Huch V Veith M Avarvari N 《Inorganic chemistry》2008,47(17):7483-7492
The dinuclear gold complexes [{Au(PPh 3)} 2(mu- dmid)] ( 1) ( dmid = 1,3-dithiole-2-one-4,5-dithiolate) and [{Au(PPh 3)} 2(mu- dddt)] ( 2) ( dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) were synthesized and characterized by X-ray crystallography. Both complexes exhibit intramolecular aurophilic interactions with Au...Au distances of 3.1984(10) A for 1 and 3.1295(11) A for 2. A self-assembly reaction between 4,5-bis(2-hydroxyethylthio)-1,3-dithiole-2-thione ( (HOCH 2 CH 2 ) 2 dmit) and [AuCl(tht)] affords the complex [AuCl{ (HOCH 2 CH 2 ) 2 dmit}] 2 ( 4), which possesses an antiparallel dimeric arrangement resulting from a short aurophilic contact of 3.078(6) A. This motif is extended into two dimensions due to intra- and intermolecular hydrogen bonds via the hydroxyethyl groups, giving rise to a supramolecular network. Three compounds were investigated for their rich photophysical properties at 298 and 77 K in 2-MeTHF and in the solid state; [Au 2(mu- dmid)(PPh 3) 2] ( 1), [Au 2(mu- dddt)(PPh 3) 2] ( 2), and [AuCl{( HOCH 2 CH 2 ) 2 dmit}] ( 4). 1 exhibits relatively long-lived LMCT (ligand-to-metal charge transfer) emissions at 298 K in solution (370 nm; tau e approximately 17 ns, where M is a single gold not interacting with the other gold atom; i.e., the fluxional C-SAuPPh 3 units are away from each other) and in the solid state (410 nm; tau e approximately 70 mus). At 77 K, a new emission band is observed at 685 nm (tau e = 132 mus) and assigned to a LMCT emission where M is representative for two gold atoms interacting together consistent with the presence of Au...Au contacts as found in the crystal structure. In solution at 77 K, the LMCT emission is also red-shifted to 550 nm (tau e approximately 139 mus). It is believed to be associated to a given rotamer. 2 also exhibits LMCT emissions at 380 nm at 298 K in solution and at 470 nm in the solid state. 4 exhibits X/MLCT emission (halide/metal to ligand charge transfer) where M is a dimer in the solid state with obvious Au...Au interactions, resulting in red-shifted emission band, and is a monomer in solution in the 10 (-5) M concentration (i.e., no Au...Au interactions) resulting in blue-shifted luminescence. Both fluorescence and phosphorescence are observed for 4. 相似文献
8.
Raoudha Abderrahim Khaled Boujlel 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):995-999
The imidates derived from 3-aminotriazole 1 react with isocyanates and isothiocyanates to give corresponding 1,2,4-triazolo-1,3,5-triazin-4-ones and 1,2,4-triazolo-1,3,5-triazin-4-thiones in a 60–75% overall yield. If the condensation is realized at r.t., then the intermediate 2 can be isolated. 相似文献
9.
Raoudha Abderrahim 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):581-585
The reaction of ethyl chloroformate with iminoesters derived from 3-aminotriazole, followed by amine or phenyl hydrazine condensation, leads to a variety of 1,2,4-triazolo-1,3,5-triazin-4-ones in a 60–85% overall yield. 相似文献
10.
Abderrahim A?t Adoubel Christophe J. Morin Nadine Mofaddel Georges Dupas Paul-Louis Desbène 《Analytical and bioanalytical chemistry》2009,394(2):597-608
Enantiomer separations of underivatised amino acids were carried out by using ligand exchange capillary electrophoresis (LECE).
Chiral discrimination is based on the formation of ternary complexes between copper(II), a chiral selector (L-proline or trans-4-hydroxy-L-proline) and an amino acid. All amino acids containing aromatic moieties or not were detected at 214 nm because
of their interactions with copper(II). In order to reduce copper(II) adsorption onto capillary walls, we used hexadimethrine
bromide to reverse the electroosmotic flow. Using this original strategy, the studied enantiomers migrated in the opposite
direction of the anodic electroosmosis. After optimising the analytical conditions taking into account the chiral resolution
and the detection sensitivity, we performed very satisfactory enantioseparations not only of aromatic amino acids (tryptophan,
tyrosine, phenylalanine and histidine) but also of aliphatic amino acids (threonine, serine, isoleucine and valine). These
enantioseparations were performed in a short analysis time at 35 °C. In order to rationalise the obtained results, we evaluated
the complexation constants corresponding to the formed ternary complexes by capillary electrophoresis and we used molecular
mechanics modelling. 相似文献