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Nanosized Fe0.2Ni0.8 particles were prepared by reducing their salts with sodium borohydride (NaBH4) in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-amonium bromide (CTAB) and n-butanol/isooctane at 25 °C. According to the TEM and X-ray diffraction analyses, the synthesized particles were around 4–12 nm in size. Due to their nanodimensions, the particles had a primitive cubic (pc) structure rather than the body-centered cubic (BCC) structure of the bulk material. An examination of the synthesis from the reverse micelle reveals that the morphology of the iron–nickel alloy nanoparticles depends mainly on the microemulsion's composition. The magnetization of the nanoparticles was much lower than that of the bulk material, reflecting the influence of the nanodimensions on the particles’ magnetizations. 相似文献
3.
Darko P. Aanin Sneana Rajkovi Dora Molnar-Gabor Milos I. Djuran 《Monatshefte für Chemie / Chemical Monthly》2004,135(12):1445-1453
Summary. Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H2O)2]2+ in which L is ethylenediamine (en), 1,2-propylenediamine (1,2-pn), isobutylenediamine (ibn), 1,2-diaminocyclohexane (1,2-dach), N-methylethylenediamine (Meen), N,N,N,N-tetramethylethylenediamine (Me4en), S-methyl L-cysteine (MeS-L-HCys), L-methionine (L-HMet), and 2,5-dithiahexane (dth) and dipeptide N-acetylated L-methionylglycine (MeCOMet-Gly) were studied by 1H NMR spectroscopy. The reactions were carried out in the pH range 2.0–2.5 and at 50°C. In all these reactions, palladium(II) complex bound to a methionine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of methionine. We found that the rate of hydrolysis and mechanism of this reaction are strongly dependent from the nature of the chelate ligand L in palladium(II) complexes of the type cis-[Pd(L)(H2O)2]2+. 相似文献
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Summary The new concept of the resonance energy in conjugated hydrocarbons introduced by Jiang Y, Zhang H (1989) Theor Chim Acta 75:279 is further developed. This model is based on expansion of the -electron energy in terms of moments which are also equal to numbers of closed walks in a molecular graph. The reference system is established by counting only acyclic walks, i.e. those tracing only on acyclic subgraphs. Because acyclic walks could be counted only up to some finite length, the energy of the reference system has been evaluated by truncating higher terms in the expansion. In this paper a finite expression for the energy of the same reference system is derived, thus allowing its exact evaluation. The exact values differ significantly from the truncated ones. This difference, as well as the discrepancy between exact results and chemical experience, are discussed. 相似文献
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J. K. Gbadago E. O. Darko C. Schandorf 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):587-599
Studies have been carried out on the distribution of major and trace elements concentrations in oxide and sulphide feed ores
at various stages of milling and processing of gold in a goldmine at Bogoso in the western region of Ghana. The studies evaluated
concentration enhancements at various stages of treatment with emphasis on understanding the typical processes leading to
enhancement of concentration at each stage and ultimately the impact from discharges into the surrounding environment. The
feed ore samples were analyzed using energy dispersive X-ray fluorescence spectrometry. The results show concentration enhancements
of a significant number of elements at some stages of processing in the two processing plants with the highest number of elements
with enhanced concentrations coming from chemically treated media of both plants. Though there are relatively high concentrations
of V (max.: 284 ppm), Cr (max.: 149 ppm), Co (max.: 84 ppm), and U (max.: 26.8 ppm) at the discharge points, the concentrations
of most of the toxic elements in the slurries discharged into the tailings dam are mostly within their respective world averages.
The enrichment indices computed for the slurries being discharged into the tailings dam suggests that the dam is not enriched
with the toxic elements Cr, Co, Ni, Zn, Cu and Pb. The enrichment index of the slurries discharged into the tailings dam decreases
in the order of oxide plant > sulphide plant. Principal component analyses performed suggest that Al2O3, K2O, Co, Zn, Cu, Y and Zr are geochemically associated. Results from the studies also suggest that the discharge of these elements
into the tailings dam may contribute insignificant pollution of the surrounding area. 相似文献
9.
A new facile synthesis of aminobisphosphonate was reported. Dibenzylamine bisphosphonate (1) is prepared from dibenzylamine, triethyl orthoformate and diethyl phosphite. Deprotection by hydrogen transfer reaction and acid hydrolysis afforded aminobisphosphonate (2). 相似文献
10.
In order to calculate the structural and compositional characteristics of microemulsions, used as eluents in the investigation of HPLC separation of simvastatin and its six impurities, predictive molecular thermodynamic approach is developed. For calculating fundamental interfacial properties of microemulsions, from pure component properties, the lattice fluid self-consistent field theory (SCF), in conjunction with new classical thermodynamic expressions, was applied. Calculation of predicted radii (PR), area per surfactant (ApS) and film thickness (FT), as well as is interfacial tension and bending moment enabled better understanding of separation of such a complex mixture. The microemulsion, which contained 1% (w/w) of diisopropyl ether, 2% (w/w) of sodium dodecyl sulphate (SDS), 6.6% (w/w) of co-surfactant such as n-butanol and 90.4% (w/w) of aqueous 25 mM disodium phosphate pH 7.0 enabled appropriate chromatographic separation between investigated compounds. It has been proved that this microemulsion had the smallest droplet radii and film thickness, which enabled optimal separation. Also the interfacial tension is the smallest, so the free energy change associated with dispersing the drops favoured a large number of small droplets. Hydrophobic interactions between solutes and stationary phase, as well as the microstructural characteristics of microemulsion eluents had a significant influence on chromatographic behavior of simvastatin and its six impurities. 相似文献