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排序方式: 共有428条查询结果,搜索用时 93 毫秒
111.
We investigate an optimal control problem described by a second-order ordinary differential equation on the interval ]0,∞[
and an integral cost functional. The study of this problem is based on a variational approach. 相似文献
112.
Władysław Janusz Svetlana Khalameida Volodymyr Sydorchuk Ewa Skwarek Valery Zazhigalov Jadwiga Skubiszewska-Zięba Roman Leboda 《Adsorption》2010,16(4-5):333-341
Mechanochemical modification of vanadium phosphates doped with Bi, Zr, Mo has been studied. Milled samples have been investigated by means of XRD, DTA-TG, FTIR, nitrogen adsorption, electrokinetic measurements. It was found that phase composition of the phosphates does not change upon the mechanochemical modification process. Milling in water causes formation of porous materials. Modification of surface results in changes of the electrokinetic and adsorption properties of the milled samples. 相似文献
113.
Jadwiga Walczak Izabella Rychłowska-Himmel Elżbieta Mikos-Nawłatyna 《Journal of Thermal Analysis and Calorimetry》1995,43(2):427-431
The phase equilibria established up to the solidus line in the system Fe2V4O13−WO3, one of the intersections of the three-component system Fe2O3−V2O5−WO3, have been studied. The system appears not to be a real two-component system.
Zusammenfassung Es wurde eine Untersuchung des Phasengleichgewichtes durchgeführt, welches bezüglich der Solidus-Linie im System Fe2V4O13−WO3, einer der Zwischenbereiche im Dreikomponentensystem Fe2O3−V2O5−WO3, nachgewiesen wurde. Dieses System scheint kein echtes Zweikomponentensystem zu sein.相似文献
114.
Studies on the three-component system Fe2O3-V2O5-WO3 have shown the occurrence of a new, compound with molecular formula FeVW2O10. Its X-ray characteristics and its melting temperature, 865±10 °C, have been established.
Zusammenfassung Einleitende Untersuchungen am Dreikomponentensystem Fe2O3-V2 O5-WO3 zeigten das Auftreten einer neuen, noch nicht publizierten Verbindung der Formel FeVW2O10. Die Verbindung wurde röntgenographisch beschrieben, ihr Schmelzpunkt beträgt 865 ±10°C.相似文献
115.
Using DTA and X-ray phase diffraction methods, a diagram of phase equilibria established in two sections of a tricomponent
oxide triangle Fe2O3-V2O5-WO3was constructed, that is, in the sections: Fe8V10W16O85-Fe2O3and Fe8V10W16O85-Fe2WO6.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
116.
A simple GF-AAS method for speciation analysis of chromium in mineral waters and salinas was developed. Cr(VI) species were separated from Cr(III) by solid-phase extraction with APDC (ammonium pyrrolidinedithiocarbamate). The APDC complexes were formed in the sample solution under proper conditions, adsorbed on Diaion HP-2MG resin and the resin was separated from the sample. After elution with concentrated nitric acid Cr(VI) was determined by GF-AAS. Total chromium was determined by GF-AAS directly in the sample and Cr(III) concentration was calculated as the difference between those results.
The detection limit of the method defined as 3 s of background variation was 0.03 μg l−1 for Cr(VI) and 0.3 μg l−1 for total chromium. RSD for Cr(VI) determination at the concentration of 0.14 μg l−1 was 9%, and for total chromium at the concentration of 5.6 μg l−1 was 5%. The recovery of Cr(VI) was in the range of 94–100%, dependently on type of the sample.
The investigation of recovery of the spiked Cr(VI) showed that at concentration levels near 1 μg l−1 and lower recovery may be reduced significantly even by pure reagents that seem to be free from any reductants. 相似文献
117.
J. Walczak J. Ziołkowski M. Kurzawa L. Trzesniowska 《Journal of Thermal Analysis and Calorimetry》1984,29(5):983-988
Phase équilibria have been investigated in the FeVO4-Fe2(MoO4)3 system for the whole concentration range of the components. In this system there is one compound which melts incongruently: Fe4V2Mo3O20. The results are presented in the form of a phase diagram.
Zusammenfassung Phasengleichgewichte im System FeVO4-Fe2(MoO4)3 wurden über den ganzen Konzentrationsbereich der Komponenten hinweg untersucht. Eine Verbindung des Systems, Fe4V2Mo3O20, schmilzt inkongruent. Die Ergebnisse sind in Form eines Phasendiagramms angegeben.
FeVO4-Fe2(MoO4)3 . Fe4V2Mo3O20, . .相似文献
118.
Phase equilibria being established in the subsolidus area of the V2O5?Cr2(MoO4)3 system at the whole component concentration range have been studied basing on DTA and X-ray phase powder diffraction. It has been established that the system is not a real two-component system in the subsolidus area. The fact has been proved by the presence of fields in that area, where three solid phases remain in mutual equilibrium. 相似文献
119.
Leboda R Charmas B Skubiszewska-Zieba J Chodorowski S Oleszczuk P Gun'ko VM Pokrovskiy VA 《Journal of colloid and interface science》2005,284(1):39-47
Natural bentonite spent in the process of plant oil bleaching was used as an initial material for preparation of carbon-mineral adsorbents. The spent bleaching earth was treated using four procedures: T (thermal treatment); H (hydrothermal treatment); C (thermal treatment with addition of CCl4 vapor); M (modification of porous structure). Raw bentonite, RB (raw bleaching earth), and carbon materials prepared using plant oil were compared. The physicochemical characteristics of the adsorbents were determined using different methods: nitrogen adsorption/desorption, XRD, TEM, and MS-TPD. Carbon-mineral adsorbents contain from 5.23 to 19.92% C (w/w) and carbon adsorbents include from 84.2 to 91.18% C (w/w). Parallel processes of organic substance carbonization, porous structure modification, sublimation or evaporation of metal chlorides, and removal of hydrogen chloride take place during pyrolysis of waste mineral materials in the CCl4 atmosphere. 相似文献
120.
J. Walczak I. Rychlowska-Himmel P. Tabero 《Journal of Thermal Analysis and Calorimetry》1999,56(1):419-422
The reaction mechanism of the synthesis of Fe8V10W16O85 was studied by means of XRD, IR spectroscopy and DTA techniques. It was found that the intermediate in the reaction may be
either FeVO4 or FeVO4 admixed with an unidentified phase X, depending on the reaction temperature. The IR spectrum of the phase Fe8V10W16O85 is reported for the first time.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献