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  • Chemistry  (2)
  • Basilar artery  (1)
  • 1
    ISSN: 1433-8491
    Keywords: Ultrasonic Doppler ; Vertebral artery ; Basilar artery ; Vertebro-basilar insufficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have examined the vertebral and subclavian arteries in 1,205 patients using directional continuous-wave (c-w) Doppler sonography, and compared the sonographic findings with the results of unilateral or bilateral retrograde brachial arteriographies in the same patients. Doppler sonography revealed 33 false positives among 909 cases with normal angiographic findings. Some types of vertebral artery (VA) lesions allowed an excellent, others a fairly good differentiation by Doppler sonography: the complete subclavian steal syndrome with constant reversal of VA flow was reliably detected (16 cases). In the incomplete steal syndrome (5 cases) sonography was superior to angiography. Two bilateral distal VA occlusions and seven basilar artery occlusions — six in the proximal third and one in the rostral third — were detected sonographically; four basilar occlusions sparing the caudal third and one case exhibiting rete mirabile anastomoses were not identified by Doppler sonography. Our acoustically defined sonographic criteria did not permit an unequivocal assignment to an anatomical variant or a vascular lesion. The sensitivity in the detection of a severe stenosis at the VA origin amounted to 16 out of 31, and to 12 of 25 in cases with a proximal VA occlusion and reconstitution of the distal VA through cervical collaterals. Our results confirm that the conventional hand-held c-w Doppler sonography cannot replace angiography in the evaluation of vertebro-basilar insufficiency. It rather serves as an aid to the decision for or against angiography, and in the follow-up of angiographically proven lesions. However, several therapeutically important lesions are readily diagnosed by sonography.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1649-1654 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of polycondensation of hydroxyfunctional polydimethylsiloxane has been studied with a simple new inexpensive piece of equipment, i.e., the vibrating needle curemeter. The order of reaction with respect to crosslinker and catalyst concentration has been determined to be unity and 0.24, respectively. The activation energy of the reaction has been found to be zero. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-2313
    Keywords: Mono-, di-, and trinuclear tantalum and tantalum | niobium complexes with P4 and P2 ligands ; m̈-η2:1:1-P2 coordination mode ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Niobium and Tantalum Complexes with P2 and P4 LigandsThe photolysis of [Cp″Ta(CO)4] 1 (Cp″ = C5H3tBu2-1,3) and P4 affords Cp″(CO)2Ta(η4-P4) 2, [{Cp″(CO)Ta}2(m̈-η2:2-P2)2] 3 and [Cp3″(CO)3Ta3(P2)2] 4. In a photochemical reaction 2 and [Cp*Nb(CO)4] 5 form [{Cp*(CO)Nb}{Cp″(CO)Ta}(m̈-η2:2-P2)2] 6 and [{Cp*(CO)2Nb} {Cp*Nb}{Cp″(CO)Ta}(m̈3-η2:1:1-P2)2] 7, a compound with the novel m̈3-η2:2:1-P2-coordination mode. The reaction of 2 and [Cp*Co(C2H4)2] 8 leads to [{Cp*Co} {Cp″(CO)Ta}(m̈-η2:2-P2)2] 9, a heteronuclear complex with an „early“ and a „late“ transition metal. Complexes 2, 3, 7 and 9 have been further characterized by X-ray structure analyses.
    Notes: Die Photolyse von [Cp″Ta(CO)4] 1 (Cp″ = C5H3tBu2-1,3) und P4 ergibt [Cp″(CO)2Ta(η4-P4)] 2, [{Cp″(CO)Ta}2(μ-η2:2-P2)2] 3 und [Cp3″(CO)3Ta3(P2)2] 4. 2 reagiert photochemisch mit [Cp*Nb(CO)4] 5 zu [{Cp*(CO)Nb}{Cp″(CO)Ta}(m̈-η2:2-P2)2] 6 und [{Cp*(CO)2Nb}{Cp*Nb} {Cp″(CO)Ta}(m̈3-η2:1:1-P2)2] 7, einer Verbindung mit der neuen m̈3-η2:2:1-P2-Koordinationsvariante. Die Reaktion von 2 und [Cp*Co(C2H4)2] 8 führt zum heteronuklearen Komplex [{Cp*Co} {Cp″(CO)Ta}(m̈-η2:2-P2)2] 9 mit einem „frühen“ und „späten“ Übergangsmetall. Die Komplexe 2, 3, 7 und 9 wurden zusätzlich durch eine Röntgenstrukturanalyse charakterisiert.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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