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1.
A graphite electrode modified with cobalt hexacyanoferrate by mechanical immobilization was used for amperometric determination of hydrazine. The modified electrode exhibits good catalytic activity for the oxidation of hydrazine at a reduced overpotential with remarkable sensitivity. The modified electrode showed a linear response for hydrazine in the concentration range of 2.0 × 10–5 to 2.8 × 10–4 M. The detection limit was 9.8 × 10–6 M (S/N = 3). The proposed modified electrode was simple, sensitive, rapid, stable and promising.  相似文献   
2.
A new copper dispersed ceramic-graphite composite electrode was fabricated by the initial mixing of copper nitrate and (3-mercaptopropyl)trimethoxy silane (MPS) followed by stirring with graphite powder. The combination of the metal catalysis and the advantages of the ceramic composite favored the electrocatalytic reduction of hydrogen peroxide (H2O2) at a reduced overpotential of -0.2 V with good sensitivity, stability and reproducibility. The sensor showed a good linear response to H2O2 in the range from 8.3 x 10(-6) M to 2.0 x 10(-3) M with a correlation coefficient of 0.9989 and the detection limit was 6.2 x 10(-6) M (S/N =3).  相似文献   
3.
A hot vacuum extraction technique for the determination of hydrogen in metal and alloy samples has been standardised. After measuring the total pressure of the evolved gases, individual hydrogen and deuterium intensities are measured using an on-line quadrupole mass spectrometer. Synthetic mixtures of H2 and D2, in known concentrations, have been analysed by QMS and an analytical expression correlating the measured [D2]/[HD] intensity ratio with the mole fraction of deuterium in the synthetic mixture has been arrived at. The precision and accuracy in the measurement of hydrogen is about 10% at 50 ppmw level.  相似文献   
4.
A newly modified electrode was prepared by mechanical immobilization of copper hexacyanoferrate (CuHCF) on a graphite electrode. The modified electrode was characterized by cyclic voltammetric experiments. The effect of different background electrolytes, pHs and scan rates on the electrochemical behaviour of the electrode has been evaluated. In NH4Cl two reversible redox peaks were observed. The first redox peak corresponding to Cu+/Cu2+ is observed only in this medium. The second redox peak corresponds to the Fe(CN)6 4–/Fe(CN)6 3– couple. Both anodic peaks were used for catalytic oxidation of ascorbic acid. As the anodic current for catalytic oxidation was proportional to the amount of ascorbic acid, an analytical method was developed for the determination of ascorbic acid in commercial samples. Received: 26 May 1998 / Revised: 15 March 1999 / Accepted: 20 March 1999  相似文献   
5.
Recent concern on international terrorism and weapons of mass destruction demands the development of novel analytical methods for identification and quantification of explosive molecules. In this article, we describe the development of high-performance immunosensors for detection of 2,4,6-trinitrotoluene (TNT), a prime component of the landmines and bombs used by terrorist and military forces. The immunosensors were constructed by physical adsorption and self-assembly methods, and their binding interactions with a monoclonal anti-TNT antibody were evaluated for TNT detection using the surface plasmon resonance technique. A home-made 2,4,6-trinitrophenyl-keyhole limpet hemocyanine conjugate was used for physical adsorption. A poly(ethylene glycol) hydrazine hydrochloride thiolate was used in the construction of self-assembled monolayer surface and was immobilized with trinitrophenyl-β-alanine by the amide coupling method. The immunosensors were highly selective, regenerable, rapid, and exhibited remarkable sensitivity down to the parts-per-trillion level for TNT by the indirect competitive inhibition principle.  相似文献   
6.
Though a variety of methods2–5 are available for the synthesis of aldehydes, this area continues to attract attention6,7 since aldehydes are important intermediates in synthetic organic chemistry. In this communication we present a new route for the synthesis of aromatic aldehydes.  相似文献   
7.
Methodology to rapidly and efficiently assemble 8-trifluoromethyltetrahydro-6H-pyrido [1,2-a] pyrazine-6-one (11) has been developed and its general applicability has been demonstrated.  相似文献   
8.
A nickel hexacyanoferrate modified electrode was constructed by mechanical immobilization. A reversible peak with midpoint potential of 0.38 V was observed in cyclic voltammetry with 0.1 M NaNO3. Electrocatalytic oxidation of thiosulfate was effective on the modified electrode at a significantly reduced overpotential of 0.5 V and at broad pH range. The modified electrode can be used for the determination of thiosulfate in the concentration range of 7.0 × 10–4 to 5.6 × 10–3 M. It has been used for the amperometric determination of thiosulfate in photographic effluents. The results obtained were in good agreement with those obtained by other methods.  相似文献   
9.
The extraction of Am(III), Pu(IV) and U(VI) as representatives of tri-, tetra- and hexavalent actinides by dibutyl-N,N-diethylcarbamoylmethylenephosphonate (DBDECMP) from nitric acid solution has ben studied with an objective of understanding the extraction mechanism. The dependence of the distribution ratios of the actinide ions was studied as a function of the concentration of H+, DBDECMP and NO 3 . The extraction data revealed that all the three actinide ions are extracted as their neutral nitrate complexes solvated by DBDECMP which behaves as neutral extractant only. The absorption spectra of DBDECMP and TBP extracts of these actinide ions were recorded. From the close similarity of these spectra it is inferred that DBDECMP acts as a monodentate extractant in the present system.  相似文献   
10.
A synthesis of the “right-wing” equivalent 22 of the ionophore antibiotic indanomycin is described, wherein an unexpected retro hetero Diels-Alder/intramolecular Diels-Alder pathway gives the desired product of the planned Claisen [3,3]-shift.  相似文献   
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