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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1944-1949 
    ISSN: 0392-6737
    Keywords: Studies of specific magnetic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si sono fatte misurazioni degli spettri di assorbimento di film sottili di HgCr2Se4 da 295 K a 25 K nell'intervallo di energia fotonica da 0.5 eV a 2.5 eV. Appare evidente che esiste un'ampia banda di assorbimento con un massimo a circa 0.93 eV a 295 K. Questa banda di assorbimento mostra uno spostamento nel rosso con la diminuzione della temperatura in corrispondenza della transizione dalla banda di valenza alla stretta banda di conduzione. Inoltre si trova che esistono altre transizioni con gap di energia di 1.20, 1.47 e 1.90 eV a 295 K. Come risultato di questa ricerca, si evidenzia la possibilità di costruire laser accordabili da questo materiale.
    Abstract: Резюме Проведены измерения спектров поглощения для тонких пленок HgCr2Se4 в области температур от 295 до 25 К с жнергией фотонов от 0.5 до 2.5 зВ. Показано, что существует сирокая полоса поглощения с максимумом вблизи 0.93 зВ при 295 К. Жта полоса поглощения обнаруживает явление красного смещения с уменьшением температуры, соответсвующей переходу из валентной зоны в узкую зону проводимости. Кроме того, мы обнаружили, что существуют другие переходы 1.20, 1.47, и 1.90 зВ при 295 К. На основе проведенного исследования мы указываем на возможность создания перестраиваемых лазеров на жтом материале.
    Notes: Summary Measurements of the absorption spectra for thin films of HgCr2Se4 were made from 295 K to 25 K in the photon energy range from 0.5 eV to 2.5 eV. It becomes evident that there exists a broad absorption band with a maximum at about 0.93 eV at 295 K. This absorption band shows a red-shift phenomenon with decreasing temperature corresponding to the transition from the valence band to the narrow conduction band. Furthermore, we find out that there exist other transitions with energy gaps of 1.20, 1.47 and 1.90 eV at 295 K. As a result of this investigation we point out the possibility of making tunable lases from this material.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1798-1802 
    ISSN: 0392-6737
    Keywords: Studies of specific magnetic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Film policristallini sottili di semiconduttore HgCr2Se4 sono stati preparati per la prima volta su substrati isolanti di cristalli singoli MgAl2O4 mediante deposizione a raggi molecolari e successiva tempra con HgSe. Si sono ottenute le condizioni ottimali per preparare film sottili a fase singola di HgCr2Se4. La resistenza magnetica e gli effetti di Hall di questi film sono stati misurati da 77 a 295 K in campi magnetici fino a 1.19·106 A/m. Diventa evidente che queste proprietà elettriche dei film sono influenzate da strati di interdiffusione nei film vicino ai substrati o dagli strati in disordine magnetico come i bordi amorfo o del grano in film.
    Abstract: Резюме Впервые приготовлены поликристаллические тонкие пленки ферромагнитных полупроводников HgCr2Se на непроводящих монокристаллических подложках MgAl2O4 с помощью осаждения молекулярного пучка и последующего отжига с HgSe. Определяются оптимальные условия для приготовления тонких пленок HgCr2Se4, имеющих единственную фазу. Измеряются, магниторезистивный эффект и эффект Холла для этих пленок в области температур от 77 до 295 К и при магнитных полях вплоть до 1.19·106 А/м. Отмечается, что на электрические свойства этих пленок влияют слои в пленках вблизи подложки или магнитноразупорядоченные слои, такие как аморфные или зернистые границы в пленках.
    Notes: Summary Polycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single-crystal substrates by molecular-beam deposition and subsequent annealing with HgSe. The optimum conditions for preparing single-phase thin films of HgCr2Se4 were obtained. The magnetoresistance and Hall effects of these films were measured from 77 to 295 K in magnetic fields up to 1.19·106 A/m. It becomes evident that these electrical properties of the films are affected by the interdiffusion layers in the films near the substrates or the magnetically disordered layers such as amorphous or grain boundaries in the films.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 21 (1981), S. 219-221 
    ISSN: 1432-1920
    Keywords: Sinus pericranii ; Diploic vein ; Superior sagittal sinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary sinus pericranii has been reported to be situated usually along the midline. Two cases of laterally situated sinus pericranii are presented. Venous blood was obtained by puncturing the tumors directly. Injection of contrast medium into the tumors demonstrated a communication between the tumors and the intracranialvenous sinuses through marked diploic veins.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Acta mathematica hungarica 35 (1980), S. 185-192 
    ISSN: 1588-2632
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 2 (1984), S. 791-798 
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Inclusion compounds of ferrocene(FcH) and its derivatives with cyclodextrins(CDs; α-CD, β-CD, and γ-CD) were prepared. CD-ferrocene inclusion compounds were obtained in a crystalline state in high yield. β-CD and γ-CD formed 1∶1 stoichiometric inclusion compounds with ferrocene and its derivatives. α-CD formed 2∶1 (CD:guest) complexes with ferrocene and the monosubstituted derivatives, but did not form complexes with 1,1′-disubstituted derivatives, α-CD-FcH and β-CD-FcH complexes are thermally stable and do not liberate ferrocene on heating at 100°C in vacuo. The cyclodextrin inclusion compounds were characterized by1H-NMR, IR, UV, and CD spectra. A large positive induced Cotton effect was observed in the case of β-CD-FcH complex, while the γ-CD-FcH complex showed a negative spectrum. The binding mode is discussed. β-Cyclodextrin was found to form inclusion complexes in ethylene glycol, diethylene glycol, triethylene glycol, methyl cellosolve, ethyl cellosolve, methyl alcohol, and glycerine solutions. γ-CD also formed complexes in ethylene glycol solution. The binding of ferrocene by β-CD is stronger in ethylene glycol than in dimethyl sulfoxide and dimethyl formamide.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl ester of trifluoroacetic acid was prepared by reaction with N,N′-dimethylformamide dimethylacetal and was successfully passed through a gas chromatograph. Trifluoroacetic acid was detected by the use of gas chromatography and low and high resolution gas chromatography mass spectrometry in an acidic extract of an incubation medium containing microsomes, reduced nicotinamide adenine dinucleotide phosphate, oxygen and halothane. However, trifluoroacetic acid could not be detected when nicotinamide adenine dinucleotide or oxygen was omitted from the incubation system. From these results, it was proved that halothane is oxidatively metabolized to trifluoroacetic acid by hepatic microsomes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 349-353 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 565-573 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-polyyne polymers consisting of palladium and conjugated acetylenic systems, where PD and R represent the  - Pd(PBu3)2 - moiety and alkyl groups, respectively, were prepared by polycondensation between palladium chlorides and α,ω-diethynyl compounds in amines using a catalytic amount of cuprous iodide. The molecular weights of the polymers formed were greatly affected by the basicity of the amines and the addition of free phosphines to the polymerization system. Under the optimum conditions, i.e., in the presence of CuI and PBu3 (in molar ratio 1/4) in piperidine at room temperature, polymer Ia (R1 = R2 = H) having M̄w = 29,000 was obtained.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 661-669 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metal-polyyne polymers consisting of transition metals and conjugated tetrayne systems where M represents —Pt(PBu3)2— or —Pd(PBu3)2— moiety were prepared by the oxidative coupling method and characterized by spectral analysis, associated with novel depolymerization giving binuclear transition metal complexes, and
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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