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161.
Nanostructured Pyrophosphate Na2PdP2O7‐Catalyzed Suzuki‐Miyaura Cross‐Coupling Under Microwave Irradiation
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Karim Dânoun Younes Essamlali Othmane Amadine Rida Tabit Aziz Fihri Christophe Len Mohamed Zahouily 《应用有机金属化学》2018,32(4)
Nanostructured palladium pyrophosphate (Na2PdP2O7) catalyst was synthesized and well characterized by using different techniques (TGA, XRD, SEM, TEM....). This nanocatalyst exhibited excellent catalytic activity in the synthesis of biaryl compounds via Suzuki‐Miyaura cross‐coupling to produce their corresponding products in good to excellent yields under mild conditions. The catalyst is recyclable and was recycled for four runs for the reaction of 4‐bromoacetophenone with phenylboronic acid without appreciable loss of its catalytic activity. 相似文献
162.
Bulk and surface properties of the ionic liquids 1-alkyl-3-methyl-imidazolium iodides ([C(n)mim]I) were simulated by classical molecular dynamics using all atom non-polarizable force field (n = 4, butyl; 6, hexyl; 8, octyl). The structure of ionic liquids were initially optimized by density functional theory and atomic charges obtained by CHELPG method. Reduction of partial atomic charges (by 20% for simulation of density and surface tension, and by 10% for viscosity) found to improve the accuracy, while a non-polarizable force field was applied. Additionally, the simulation ensembles approach the equilibrium faster when the charge reduction is applied. By these refined force field parameters, simulated surface tensions in the range of 323-393 k are quite in agreement with the experiments. Simulation of temperature dependent surface tension of [C(4)mim]I well beyond room temperature (up to 700 K) permits prediction of the critical temperature in agreement with that predicted from experimental surface tension data. Simulated densities in the range of 298-450 K for the three ionic liquids are within 0.8% of the experimental data. Structural properties for [C(4)mim]I were found to be in agreement with the results of Car-Parrinello molecular dynamics simulation we performed, which indicates a rather well-structured cation-anion interaction and occurs essentially through the imidazolium ring cation. Diffusion coefficient changes with alkyl chain length in the order of [C(8)mim]I > [C(6)mim]I > [C(4)mim]I for the cation and the anion. Formation of a dense domain in subsurface region is quite evident, and progressively becomes denser as the alkyl chain length increases. Bivariate orientational analysis was used to determine the average orientation of molecule in ionic liquids surface, subsurface, and bulk regions. Dynamic bisector-wise and side-wise movement of the imodazolium ring cation in the surface region can be deduced from the bivariate maps. Atom-atom density profile and bivariate analysis indicate that the imidazolium cation takes a spoon like configuration in the surface region and the tilt of alkyl group is a function length of alkyl chain exposing as linear as possible to the vapor phase. 相似文献
163.
164.
Fahs Marwan Graf Thomas Tran Tuong Vi Ataie-Ashtiani Behzad Simmons Craig. T. Younes Anis 《Transport in Porous Media》2020,131(2):537-568
Transport in Porous Media - Natural convection in a porous enclosure in the presence of thermal dispersion is investigated. The Fourier–Galerkin (FG) spectral element method is adapted to... 相似文献
165.
Ksila Wafa Younes Mohamed Kadri Ghorbel Abdelhamid Rives Alain 《Journal of Sol-Gel Science and Technology》2021,99(2):376-390
Journal of Sol-Gel Science and Technology - Our work is focused on the research of new zirconia doped telluric acid catalysts prepared with sol–gel method. Optimization of different... 相似文献
166.
167.
Rafael Leite de Oliveira Hernane da Silva Barud Rosana M. N. de Assunção Carla da Silva Meireles Geandre Oliveira Carvalho Guimes Rodrigues Filho Younes Messaddeq Sidney José Lima Ribeiro 《Journal of Thermal Analysis and Calorimetry》2011,106(3):703-709
In this study, microcrystalline cellulose (MCC) was prepared from the acid hydrolysis of bacterial cellulose (BC) produced
in culture medium of static Acetobacter xylinum. The MCC-BC produced an average particle size between 70 and 90 μm and a degree of polymerization (DP) of 250. The characterization of samples was performed by thermogravimetric analysis, X-ray diffraction, and scanning electron
microscopy (SEM). The MCC shows a lower thermal stability than the pristine cellulose, which was expected due to the decrease
in the DP during the hydrolysis process. In addition, from X-ray diffractograms, we observed a change in the crystalline structure.
The images of SEM for the BC and MCC show clear differences with modifications of BC fiber structure and production of particles
with characteristics similar to commercial MCC. 相似文献
168.
Younes Valadbeigi 《International journal of quantum chemistry》2017,117(3):190-196
A new class of superacids was designed using enolic derivatives of fulvene. After deprotonation, bond rearrangement leads in a stable conjugate base with an aromatic cyclopentadienyl ring and a carboxyl group. The gas phase enthalpies ( ) of the deprotonation, as an index of acidity, were calculated employing the B3LYP method and 6‐311++G(d,p) and aug‐cc‐PVDZ basis sets. The acidity of these compounds without any electron withdrawing groups was more than H2SO4 in gas phase. The acidity increased by substituting electron withdrawing groups (? F, ? CN, and ?O) into the molecules so that we could achieve a cyano derivative of fulvene with = 250 kcal/mol. 相似文献
169.
Intramolecular H-transfer reactions in cis-HO3 and CH2OO were studied at the MP2 and B3LYP levels of theory. Activation energies (E a) and Gibbs free energies of activation (?G #) of the H-transfer reactions were calculated. The activation energies of the H-transfer in cis-HO3 and CH2OO were about 110 and 130 kJ/mol, respectively. Catalytic effects of some protic molecules including HCOOH, CH3OH, NH3, CH3NH2, HOCl, H2O2, and H2O, on the activation energies and transition state structures were studied. The more stable transition state structures were obtained in the presence of the protic molecules. Our calculations showed that the protic molecules decrease the activation energies of the H-transfer reactions about 50 kJ/mol. 相似文献
170.
Shaaban K. Mohamed Sabry H. H. Younes Eman M. M. Abdel‐Raheem Joel T. Mague Mehmet Akkurt Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(11):959-964
The wide diversity of applications of thiosemicarbazones and bis(thiosemicarbazones) has seen them used as anticancer and antitubercular agents, and as ligands in metal complexes designed to act as site‐specific radiopharmaceuticals. Molecules of 1,1′‐({[(ethane‐1,2‐diyl)dioxy](1,2‐phenylene)}bis(methanylylidene))bis(thiosemicarbazide) {alternative name: 2,2′‐[ethane‐1,2‐diylbis(oxy)]dibenzaldehyde bis(thiosemicarbazide)}, C18H20N6O2S2, (I), lie across twofold rotation axes in the space group C2/c, with an O—C—C—O torsion angle of −59.62 (13)° and a trans‐planar arrangement of the thiosemicarbazide fragments relative to the adjacent aryl rings. The molecules of (I) are linked by N—H...S hydrogen bonds to form sheets containing R24(38) rings and two types of R22(8) ring. In the N,N‐dimethylformamide disolvate, C18H20N6O2S2·2C3H7NO, (II), the independent molecular components all lie in general positions, but one of the solvent molecules is disordered over two sets of atomic sites having occupancies of 0.839 (3) and 0.161 (3). The O—C—C—O torsion angle in the ArOCH2CH2OAr component is −75.91 (14)° and the independent thiosemicarbazide fragments both adopt a cis‐planar arrangement relative to the adjacent aryl rings. The ArOCH2CH2OAr components in (II) are linked by N—H...S hydrogen bonds to form deeply puckered sheets containing R22(8), R24(8) and two types of R22(38) rings, and which contain cavities which accommodate all of the solvent molecules in the interior of the sheets. Comparisons are made with some related compounds. 相似文献