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121.
CdSe/ZnS QDs have demonstrated capacity to act as reducing agent in organic media such as acetonitrile and ethanol. By using fluorescence and Raman spectroscopy, it has been demonstrated that QDs reduce diquat herbicide to its monocation radical. The reaction is characterized to present a high reaction rate making possible to perform the reaction by simple filtration of the solution containing the herbicide through a QDs modified filter. The monocation radical presents a high fluorescence emission spectrum which was selected as the analytical signal to quantify the diquat herbicide. The method described here for the analysis of diquat herbicide in oat grains is simple and fast allowing the analysis of trace level of herbicide in only 6 min. The excellent sensitivity and reproducibility of the methods indicate that the reaction is favoured from both thermodynamic and kinetic point of view. The results presented open up the possibility to use QDs as redox agent. The sensitivity of the method expressed as detection limit was only of 0.01 mg kg(-1).The lineal range was between 0.05 and 0.5 mg kg(-1). The time of analysis per sample, including extraction, reaction and fluorescent measurement was only of 6 min. 相似文献
122.
Simonet Torres Guillermo Ferraudi Maria Jesus Aguirre Mauricio Isaacs Betty Matsuhiro Nancy P. Chandía Leonora Mendoza 《Helvetica chimica acta》2011,94(2):293-300
In contrast to the UV‐photoinduced ligand photoionization of the flavonoid complexes of FeIII, redox reactions initiated in ligand‐to‐metal charge‐transfer excited states were observed on irradiation of the quercetin ( 1 ) and rutin ( 2 ) complexes of CuII. Solutions of complexes with stoichiometries [CuIIL2] (L=quercetin, rutin) and [CuII2Ln] (n=1, L=quercetin; n=3, L=rutin) were flash‐irradiated at 351 nm. Transient spectra observed in these experiments showed the formation of radical ligands corresponding to the one‐electron oxidation of L and the reduction of CuII to CuI. The radical ligands remained coordinated to the CuI centers, and the substitution reactions replacing them by solvent occurred with lifetimes τ<350 ns. These are lifetimes shorter than the known lifetimes (τ>1 ms) of the quercetin and rutin radical's decay. 相似文献
123.
Sandra Benítez‐Martínez Bartolomé M. Simonet Miguel Valcárcel 《Electrophoresis》2013,34(17):2561-2567
The exceptional properties of graphene (G) were exploited here to facilitate capillary electrokinetic separations. Two types of commercially available G consisting of nanoparticles containing—one to three and—four to six G sheets, respectively, were compared for this purpose. Both proved effective in separating the arylpropyl derivatives of nonsteroidal anti‐inflammatory drugs. The highest resolution and shortest migration times were obtained with G containing high amount of single and double G nanosheets. G affords higher resolution than other types of nanoparticles; stable suspensions can be easily prepared and used as BGE without the need of adding an additional surfactant. This results in a high reproducibility in migration times and stability in background noise. The LOD and LOQ obtained by using G nanoparticles as pseudostationary phases spanned the range 0.29–1.18 mg/L and 0.95–3.95 mg/L, respectively, and the RSD was less than 4.7% in all instances. 相似文献
124.
This paper describes a simple approach to determine gold nanoparticles in liver and river water samples. The method of purification of nanoparticles from the matrix is based on the stabilization of gold nanoparticles with a cationic surfactant followed by a microliquid-liquid extraction in ionic liquid. Finally, the extracted nanoparticles can be analysed by UV/Vis detection or Raman spectroscopy. The precision of the proposed method for the analysis of liver tissue and river water samples was 9.7% and 18% respectively for UV/Vis analysis. The sensitivity was 1.17 × 10(-12) M for the analysis of 3 mL of liver homogenate or river water sample. 相似文献
125.
Jacques Simonet 《Electrochemistry communications》2009,11(1):134-136
The easy reaction of primary alkyl iodides RI with palladium metal is used to transport elemental palladium onto solid cathodes (Glassy carbon, gold, platinum, nickel, etc.). The principle is to create suspensions of palladium particles in solutions of RI’s in aprotic polar solvents. Electroactive species are [R–Pd+, I?] that cover palladium grains and may discharge (according to a one-electron process) at electrified substrates for liberating Pd. This procedure efficiently produces palladium nano-aggregates and easily yields chemically modified surfaces with a large palette of substrates. 相似文献