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排序方式: 共有213条查询结果,搜索用时 15 毫秒
11.
This paper presents results of measurements of the specific heat and electrical resistivity of a 53%Ni-47%Ti superconducting alloy. Both properties were measured by a contact variant of the millisecond-resolution pulse calorimeter. W5%Re/W25%Re thermocouple thermometry enabled study from ambient temperature to 2000 K. Results are discussed, and their uncertainty is estimated. 相似文献
12.
Marko Hrovat Darko Belavič Zoran Samardžija Janez Holc 《Journal of Materials Science》2001,36(11):2679-2689
Some commercial thick film resistors with sheet resistivities from 1 kohm/sq. up to 1 Mohm/sq. were evaluated for strain gauge applications. Temperature coefficients of resistivity, noise indices and gauge factors (GFs) were measured. For the same resistor series GFs and noise indices increase with increasing sheet resistivity. However, both GFs and noise indices are different for resistors with the same nominal sheet resistivity but from different resistor series. The results indicated that the microstructure rather than the different chemical composition of the conductive phase in thick film resistors is the primary reason for the different gauge factors. 相似文献
13.
Darko B. Mitić Goran S. Jovanović Mile K. Stojčev Dragan S. Antić 《International Journal of Electronics》2013,100(3):362-375
Phase-synchronisers have many applications in VLSI circuit designs. They are used in CMOS RF circuits including phase (de)modulators, phase recovery circuits, multiphase synthesis, etc. In this article, a phase-synchroniser based on gm-C all-pass filter chain with sliding mode control is presented. The filter chain provides good controllable delay characteristics over the full range of phase and frequency regulation, without deterioration of input signal amplitude and waveform, while the sliding mode control enables us to achieve fast and predetermined finite locking time. IHP 0.25 µm SiGe BiCMOS technology has been used in design and verification processes. The circuit operates in the frequency range from 33 MHz up to 150 MHz. Simulation results indicate that it is possible to achieve very fast synchronisation time period, which is approximately four time intervals of the input signal during normal operation, and 20 time intervals during power-on. 相似文献
14.
Darko Makovec Miha Drofenik rej nidari 《Journal of the American Ceramic Society》1999,82(5):1113-1120
Manganese zinc (MnZn) ferrite powders were prepared via the hydrothermal treatment of a homogeneous mixture of the raw oxides (i.e., Fe2 O3 , ZnO, and Mn3 O4 or MnO) at temperatures of 220°-320°C in air or an inert atmosphere. The final results of the hydrothermal reactions between the raw oxides were fine powders with a heterogeneous phase composition. In addition to lower concentrations of the residual reactants (Fe2 O3 , Mn3 O4 ), two types of spinel-structure-based reaction products-ferrite ((Mn2+ ,Zn)Fe2 O4 ) and manganate ((Zn,Mn2+ )Mn2 3+ O4 )-were detected after the synthesis. The composition of the ferrite products, as well as the ratio of ferrite products to manganate products, were mainly functions of the oxidation state of the manganese that was present during treatment. The oxidation state of manganese during reaction was dependent on the valence of the manganese in the starting manganese oxide and on the atmosphere in the autoclave during reaction. When the hydrothermal reaction was conducted in air, almost-pure zinc ferrite was identified, whereas during reaction in an inert atmosphere, MnZn ferrite was formed. The kinetics of the hydrothermal reactions also were dependent on the oxidation state of manganese, as well as the temperature and specific surface area of the starting Fe2 O3 . 相似文献
15.
16.
Carl W. Brown III Dr. Matthew R. Lakin Dr. Darko Stefanovic Dr. Steven W. Graves 《Chembiochem : a European journal of chemical biology》2014,15(7):950-954
Chemical reactions catalyzed by DNAzymes offer a route to programmable modification of biomolecules for therapeutic purposes. To this end, we have developed a new type of catalytic DNA‐based logic gates in which DNAzyme catalysis is controlled via toehold‐mediated strand displacement reactions. We refer to these as DNAzyme displacement gates. The use of toeholds to guide input binding provides a favorable pathway for input recognition, and the innate catalytic activity of DNAzymes allows amplification of nanomolar input concentrations. We demonstrate detection of arbitrary input sequences by rational introduction of mismatched bases into inhibitor strands. Furthermore, we illustrate the applicability of DNAzyme displacement to compute logic functions involving multiple logic gates. This work will enable sophisticated logical control of a range of biochemical modifications, with applications in pathogen detection and autonomous theranostics. 相似文献
17.
Magnetic maghemite nanoparticles in the form of nanosheets were prepared by a topotactic transformation during the dehydroxylation of a γ-FeO(OH) precursor. The precursor was synthesized from tetrapyridin Fe(II) chloride (Fe(py)4Cl2). The nanosheets are several hundreds of nanometers wide, and less than 5 nm thick; they frequently bend and curl at the edges; they are nanocrystalline; and they are composed of smaller maghemite nanostructured domains, from a few nanometers up to several tens of nanometers wide. 相似文献
18.
Darko Makovec Zoran Samardzija Drago Kolar 《Journal of the American Ceramic Society》1997,80(12):3145-3150
Incorporation of Nd into the BaCeO3 perovskite structure was studied by quantitative wavelength dispersive spectroscopy-electron probe microanalysis (WDS/EPMA) in combination with scanning electron microscopy (SEM) and X-ray powder diffractometry (XRPD). Highly Nd-doped BaCeO3 specimens, synthesized by mixed oxide technology, were sintered at 1400°C in ambient air. Concentrations of cations obtained by microanalysis were calculated to the ABO3 perovskite formula, considering incorporation of Nd at Ba as well as at Ce sites. Nd-BaCeO3 solid solutions may be represented by the general formula Ba1− X Nd X Ce1− Y NdY O3−( Y-X )/2 ( V O )( Y-X )/2 . The ratio between Nd incorporated at Ba sites and at Ce sites ( X/Y ) is a function of the starting composition, changing from 1 in the CeO2 -rich part of the BaO-CeO2 -Nd2 O3 system, to ~0.1 in the BaO-rich part of the system. 相似文献
19.
20.
Darko Makovec Zoran Samardija Uro Delalut Drago Kolar 《Journal of the American Ceramic Society》1995,78(8):2193-2197
Incorporation of La3+ into the BaTiO3 lattice was studied on samples of various composition, using quantitative WDS microanalysis (EPMA) in combination with scanning electron microscopy (SEM) and X-ray powder diffractometry (XRPD). Direct determination of solid-solution formulas by microanalysis supports the structure model of a solid solution with La3+ on Ba2+ sites and a deficient Ti4+ sublattice, independent of the starting composition. Solid solution extends on the tie line, which points from BaTiO3 to La4 Ti3 O12 , to the composition of approximately Ba0.70 - La0.38 Ti0.925 ( V "")0.075 O3 . On the basis of these results, the BaTiO3 -rich part of the BaO-La2 O3 -TiO2 phase diagram was constructed. 相似文献