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Safwat A. Ahmed Desmond Slade Ikhlas A. Khan Mahmoud A. ElSohly 《Tetrahedron letters》2008,49(42):6050-6053
Three new cannabichromanone derivatives were isolated from high potency cannabis, along with the known cannabichromanone. Full spectroscopic data, including the use of electronic circular dichroism and Mosher ester analysis to determine the absolute configuration of these compounds, are reported. All isolates were tested for antimicrobial, antimalarial, antileishmanial, and anti-oxidant activities. 相似文献
34.
Substitute Effect on the Structure,Stability of Valence Isomers and Aromaticity of 1‐H‐Boratabenzene
Density functional theory (B3LYP) calculations were performed on the Me and F substituted valence isomeric forms of 1‐H‐boratabenzene. The calculations revealed that the planar benzene analog is the lowest energy isomer. Its aromaticity is analyzed in the light of the nucleus‐independent chemical shift (NICS) and shows that aromaticity increases in F substituted, but decreases in Me substituted. These calculations indicate substitution of BH with BMe and BF doesn't cause significant variation in bond length. 相似文献
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Pulsed 7Li NMR relaxation time measurements are reported for the intercalate Li0.40MoO3 in the temperature range 200K < T < 460K at 20 MHz. Temperature dependences of T1 and T2 indicate translation of Li+ with EA = 23 kJ mol-1. The data lead to an estimate for the Li+ self-diffusion coefficient at 300K of D1300K ? 4 x 10-12 cm2 sec-1. 相似文献
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We report the polarized infrared reflectance of (-methylphenazinium)x (phenazine)1-x(tetracyanoquinodimethanide), (NMP)x(Phen)1-x(TCNQ) for 0.5≤x≤1.0. We demonstrate that the “Drude edge” in TCNQ salts is related to the conduction electron charge density. An anomalous rapid red shift of the plasma frequency, observed for , may signal the emptying of the conduction electrons from half of the chains and/or a crossover from small U/W (coulomb repulsion/bandwidth) to large U/W behavior. 相似文献
38.
Beheshti N Bu H Zhu K Kjøniksen AL Knudsen KD Pamies R Hernandez Cifre JG García de la Torre J Nyström B 《The journal of physical chemistry. B》2006,110(13):6601-6608
The formation of associative networks in semidilute aqueous solutions of hydrophobically modified hydroxyethylcellulose (HM-HEC) is dependent on intermolecular hydrophobic interactions. Addition of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) monomers to the system provides decoupling of these associations via inclusion complex formation with the polymer hydrophobic tails. Results from viscosity, polymer NMR self-diffusion, and dynamic light scattering (DLS) measurements show that the hydrophobic interactions in HM-HEC solutions are effectively suppressed when the level of HP-beta-CD addition increases. Small-angle neutron scattering (SANS) results reveal that the large-scale association complexes in HM-HEC solutions are strongly diminished when the concentration of HP-beta-CD rises. The time correlation data obtained from the DLS experiments unveiled the existence of two relaxation modes: one single exponential at short times followed by a stretched exponential at longer times. The fast mode is always diffusive, whereas the slow mode exhibits progressively stronger wavevector dependence as the intensity of the hydrophobic interactions increases. This feature, as well as the accompanying drop of the stretched exponential beta as the HP-beta-CD concentration decreases, is attributed to enhanced hydrophobic interactions and can be well rationalized in the framework of the coupling model of Ngai. 相似文献
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Qamar Salamat Yadollah Yamini Morteza Moradi Abolfazl Farahani Neda Feizi 《Journal of separation science》2019,42(8):1620-1628
In the present study, a supramolecular solvent was formed from reverse micelle aggregates of octanol. The proposed supramolecular solvent was used for rapid extraction of some antidepressants drugs including amitriptyline, imipramine, desipramine, maprotiline, sertraline, and doxepin from biological samples. Alkanol‐based supramolecular solvents have a unique array of physicochemical properties, making them a very attractive alternative to replace organic solvents in analytical extractions. The parameters affecting the extraction of target analytes (i.e., the volume of tetrahydrofuran and octanol as the major components comprising the supramolecular solvent, chain length of alkanols, sample solution pH, salt addition, and ultrasonic time) were investigated and optimized by factor by factor optimization method. Under the optimum conditions, preconcentration factors of 470, 490, 460, 385, 370, and 430 were obtained for amitriptyline, doxepin, imipramine, desipramine, maprotiline, and sertraline, respectively. The linear ranges and coefficients of determination (R2) were obtained in the range of 0.01–100 μg/L and 0.9974–0.9991, respectively. Also the limits of detection (S/N = 3) of 0.003–0.03 μg/L, and precisions (n = 5) of 4.9–8.9% were calculated. Finally, the method was successfully applied for the extraction of antidepressant drugs in biological samples, and relative recoveries in the range of 91–102% were obtained. 相似文献
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Molecular Diversity - In this research, QSAR modeling was carried out through SMILES of compounds and on the basis of the Monte Carlo method to predict the antioxidant activity of 79 derivatives of... 相似文献