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211.
Gold Surface Functionalization with S‐containing Organic Compounds and Gold Nanoparticles for Ethylene Glycol Electrooxidation 下载免费PDF全文
In this work a gold electrode modified with self‐assembled layers (SAMs) composed with organic S‐containing compound and gold nanoparticles was prepared. The electrode with SAMs endowed with gold nanoparticles gave the high catalytic effect for ethylene glycol (EG) electrooxidation in solution at pH 7. For this novel sensor a linear relationship between the current response of EG at the potential of peak maximum (jp) and the concentration of this compound in solution (cEG) was found over the range 0.1 µM to 0.7 M with the detection sensitivity jp/cEG equal to about 5 A cm?2 mol?1 dm3 (at v=0.1 V s?1) and the detection limit of 0.046 µM. 相似文献
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213.
Campaña AG Estévez RE Fuentes N Robles R Cuerva JM Buñuel E Cárdenas D Oltra JE 《Organic letters》2007,9(11):2195-2198
We describe how alkenes and alkynes can be hydrogenated under mild conditions by hydrogen transfer from water mediated by titanocene(III) and a substoichiometric quantity of one of the late transition metals usually employed as hydrogenation catalysts. This process proceeds presumably by H-atom transfer from TiIII-coordinated water to the late transition metal partner (depicted in the drawing above), a mechanism in support of which we provide theoretical and experimental evidence. 相似文献
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215.
An azido-metal-1,2,4-triazolate coordination polymer, [Cu(trz)(N(3))](n) (trz = 1,2,4-triazolate) was synthesized using hydrothermal methods; the complex has a rare three-dimensional non-interpenetrated utp or (10,3)-d topological network structure and exhibits spin-canted antiferromagnetism at low temperature. 相似文献
216.
Li JR Yu Q Tao Y Bu XH Ribas J Batten SR 《Chemical communications (Cambridge, England)》2007,(22):2290-2292
The in situ solvothermal reaction of 3,4-dicyano-1,2,5-thiadiazole with MCl(2) (M = Co, Ni) and NaOH afforded two isomorphous complexes, [M2(L)2(H(2)O)2]n (L = 2,1,3-thiadiazole-4,5-dicarboxylate), which exhibit a rare non-interpenetrated (10,3)-d (utp) network topology and interesting magnetic behaviors: spin-canted antiferromagnetism for the Co(II) complex, but simple antiferromagnetic coupling for the Ni(II). 相似文献
217.
A liquid chromatographic chiral stationary phase (CSP) based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6, which has been utilized in the resolution of alpha-amino acids, amines and amino alcohols, was treated with excess of n-octyltriethoxysilane to prepare a new improved CSP. The residual silanol groups of the original CSP were protected by n-octyl groups in the new CSP. The chiral recognition ability of the new CSP was superior to that of the original CSP in the resolution of alpha-amino acids, amines and amino alcohols. Retention factors (k1) for the resolution of alpha-amino acids were lower on the new CSP than on the original CSP while those for the resolution of amines and amino alcohols were higher on the new CSP than on the original CSP. The improved chiral recognition ability of the new CSP and the retention behaviors of the two enantiomers on the new CSP have been rationalized to stem from the removal of the non-enantioselective interactions between the analytes and the residual silanol groups of the original CSP and the improved lipophilicity of the CSP. 相似文献
218.
Controlled construction of uniform pompon-shaped microarchitectures self-assembled from single-crystalline lanthanum molybdate nanoflakes 总被引:1,自引:0,他引:1
Bu W Xu Y Zhang N Chen H Hua Z Shi J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(17):9002-9007
Uniform three-dimensional La2(MoO4)3 nanostructures with a pompon shape have been successfully constructed by a simple surfactant-free hydrothermal approach via self-assembly from single-crystalline nanoflakes. The formation of the uniform pompon-shaped La2(MoO4)3 microarchitectures is closely related to the presence of a proper amount of ammonium ions, and it is proposed that the pompon-shaped microarchitecture forms through an electrostatic attraction/repulsion effect between the oppositely charged flat surface and the edge of nanoflakes. Without the introduction of ammonium ions, no pompon-shaped microarchitectures can be formed, and while under the presence of excess ammonium ions, the nanoflakes on the micropompons become amorphous, twisted, and rugged. The novel microarchitectures of the product can be successfully modified from spherical to columelliform by using a mixed solvent of water/ethanol. This simple and efficient method may provide a practical reference to the controlled synthesis of other microarchitectures. 相似文献
219.
The structures and properties of the O2+O2− electron transfer system in the quartet state, both in the gaseous phase and in solution, were studied at the UMP2(full)/6-311+G* basis set level for the five selected coupling structures: two T-type, collinear, parallel, and crossing. The stabilities of these encounter complexes were compared. The activation barriers, coupling matrix elements, and the electron transfer rate at two theoretical levels (semiclassical and quantum mechanical) were also calculated for the quartet state, and the effect of the solvent medium evaluated at the self-consistent reaction field level. Results indicate that the structures and properties of the encounter complexes directly affect the mechanism and rate of the electron transfer reaction, the contact distances for this O2…O2− were generally large (3 Å), the interaction between the donor and the acceptor was weak, and the structures are floppy. The electronic transmission factor for the reacting system, O2+O2−, was less than unity (ca. 001–0.6), thus the electron transfer reaction was non-adiabatic in nature. Analysis of the dependence of relevant kinetic parameters on various influencing factors showed that the effect of the solvent medium on the coupling matrix element was small, but that on the electron transfer rate was very large, and the gaseous phase results for the molecular geometrical parameters and their contributions can directly transfer to solution. Among the five selected transition state structures, the electron transfer was more likely to take place via the T-type and the P-type structures, the rate values from two theoretical levels were in good agreement with each other and were also very close to the experimental findings. If the various anharmonic vibrational contributions, the effect of the solvent molecular electronic structures and the interaction between the reacting species and the solvent medium are taken into account, the results can be improved. 相似文献
220.
This paper presents liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) approaches for the rapid characterization of three urinary isomeric metabolites and their two precursor metabolites of SYN-2836, a novel antifungal agent, in dogs administered multiple oral doses of the agent (30 mg kg(-1) day(-1)). A collection of correlative data regarding the SYN-2836 metabolites was obtained by LC/MS and LC/MS/MS performed under complementary conditions such as the columns (C(18) vs cyano type), the mobile phase systems (acetonitrile-water-formic acid vs acetonitrile-water-ammonium acetate) and the electrospray ionization modes (positive vs negative). Metabolite identification was accomplished based on not only the LC/MS/MS data (product ion spectra) but also the LC/MS data indicating chromatographic behaviors of the metabolites. SYN-2836 and SYN-2869, an analog of the former, showed almost the same metabolic pathways following the same multiple-dose administration of the individual agents to the dogs. Therefore, correlation analysis in product ion spectra between corresponding metabolites of SYN-2836 and SYN-2869, and also in metabolic pathways between the two agents, was strategically used to facilitate the identification of the SYN-2836 (and SYN-2869 if necessary) metabolites. For the reason that various elucidation strategies were used complementarily, the chemical structures of the metabolites were unambiguously attained and the isomeric metabolites were explicitly differentiated without the use of other analytical methods. The methodologies used in this study may be applicable to metabolite screening of several structurally related agents simultaneously, promoting lead finding and optimization of drug candidates using a metabolism-based approach. 相似文献