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  • 1
    ISSN: 1435-1536
    Keywords: Proton-NMR ; spin-spin-relaxation ; lineshape analysis ; multicomponent polimeric systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Abstract A method is presented to study the proton spin-spin-relaxation of one and two phase polymeric systems in a time range of 10−6 to 10−1 s, using a logarithmic time scale. Observing the line shape of the free induction decay (FID), an extensive description of the relaxation behaviour is possible in case of one phase systems in the temperature range from the rigid solid to the melt, and in case of two phase systems (in the temperature range between the glass temperatures of each phase) for each phase separately. By a combination of serveral pulse methods known from the literature, the true shape of the FID's is measured. The FID's are analyzed by comparison with simple mathematical line shapes. Several examples of measurements and analyses are discussed.
    Notes: Zusammenfassung Als Grundlage von Polymeruntersuchungen wird ein Meßverfahren vorgestellt, das die Beobachtung der Protonen-Spin-Spin-Relaxation von Ein- und Zweiphasensy steinen in einem Zeitbereich von 10−6 bis 10−1 s unter Verwendung einer logarithmischen Zeitachse gestattet. Hierdurch wird eine einwandfreie Kennzeichnung der Einphasensysteme hinsichtlich der Kettenbeweglichkeit vom Festbis in den Schmelzzustand und der Zweiphasensysteme für jede Phase separat ermöglicht. Durch die Kombination einer Reihe von in der Literatur beschriebener Meßverfahren werden Störeffekte, die die Relaxationskurve verzerren, ausgeschaltet. Die gemessenen Relaxationskurven werden durch Vergleich mit geeigneten Kurvenprofilen mathematisch analysiert. Einige Anwendungsbeispiele werden diskutiert.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 240 (1984), S. 43-48 
    ISSN: 1434-4726
    Keywords: Biochemical analysis ; Perilymph ; Sources of error ; Cerebrospinal fluid ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Contamination of perilymph with other fluids (cerebrospinal fluid, tissue fluid, blood, endolymph) together with sampling, anaesthesia, surgical intervention or food intake of the animals may considerably affect the analytical result. The numerous possible artefacts seem to be the main reason why varying values are given in the literature for the same chemical component of perilymph. This is also partly true of cerebrospinal fluid and blood. The effect of some sources of error on selected chemical components of perilymph, cerebrospinal fluid and blood is briefly summarized.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 143 (1984), S. 35-40 
    ISSN: 1432-1076
    Keywords: Chronic intrahepatic cholestasis ; Biliary lipid composition ; Bile acids ; Gallstones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Biliary lipid composition, standard liver function tests, serum lipids and faecal fat excretion were studied in 15 children with chronic intrahepatic cholestasis (severe intrahepatic cholestasis, n=6; paucity of intralobular bile ducts, n=4; benign recurrent cholestasis, n=5) and compared to 15 children without gastrointestinal diseases. Severe and benign intrahepatic cholestasis were associated with normal or moderately elevated serum lipids. Biliary lipid concentrations were extremely reduced, bile acid concentrations were below the critical micellar concentration. This may account for the high incidence of gallstone formation in these patients. Remission periods in patients with benign recurrent cholestasis were not followed by complete normalisation of biliary lipid concentrations, indicating a primary defect in hepatic excretory function. Children with paucity of intralobular bile ducts showed markedly increased serum lipids, but only a two-fold reduction in biliary lipid concentrations. Cholic acid was the predominant bile acid in bile of all cholestatic children even during remission. Neither increased levels of monohydroxy bile acids nor unusual bile acids could be identified in notable amounts.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 143 (1984), S. 41-44 
    ISSN: 1432-1076
    Keywords: Chronic intrahepatic cholestasis ; Biliary lipid composition ; Bile acids ; Phenobarbital
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of phenobarbital (5.4–7.5 mg/kg body weight) for 14 days were studied in four children with severe intrahepatic cholestasis (group I) and in four with a syndromatic type of paucity of intralobular bile ducts (group II). Phenobarbital administration resulted in a moderate improvement of pruritus in all patients. There was a significant decrease of bilirubin in serum (group I: from 4.8 to 2.7 mg/dl; group II: from 6.1 to 2.1 mg/dl); total bile acids (group I: from 416 to 337 μmol/l; group II: from 156 to 123 μmol/l) and cholesterol (group I: from 248 to 207 mg/dl; group II: from 351 to 292 mg/dl). Alkaline phosphatase activity increased from 929 to 1126 U/l in group I and from 1751 to 2360 U/l in group II. SGOT and SGPT activities remained unchanged in both groups. In group I total biliary lipid concentration and bile acid output increased from 0.09 to 0.17 g/dl and from 3.9 to 7.2 μmol/kg per 30 min, respectively. Molar percentages of cholesterol, phospholipids and bile acids in bile remained unchanged. In group II total lipid concentrations and bile acid output increased from 1.62 to 2.0 g/dl and from 27.8 to 39.1 μmol/kg per 30 min, respectively. The molar percentage of cholesterol decreased from 5.6 to 3.5 mol%. The present results indicate that short term administration of phenobarbital has only minimal effects on biliary lipid metabolism in children with chronic intrahepatic cholestasis.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1574-4647
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The redistribution of conconavalin A (Con A) receptors on peripheral blood mononuclear cells was studied in young adult patients with Down’s syndrome (DS), and young-adult controls and aged normal volunteers. DS was included in the study as it shows many features of accelerated aging. The percentage of Con A capping was markedly lower in DS patients and aged individuals than in young-adult controls. Colchicine displayed a significant enhancing effect on Con A capping in DS patients and aged individuals, but a moderate inhibitory effect on Con A capping in the young adults. The enhancing effect in DS patients and aged volunteers suggests the possibility that an excess of polymerized tubulin (microtubules) may occur in lymphocytes during normal or accelerated aging.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 355 (1981), S. 549-549 
    ISSN: 1435-2451
    Keywords: Resection of the ileum ; Postoperative symptomes ; Ileumresektion ; Postoperatives Beschwerdebild
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zur Erfassung des klinischen Beschwerdebildes dünndarmresezierter Patienten wurden von 197 Patienten mit isolierter Dünndarmresektion aus den Jahren 1958-1978 der Chirurgischen Universitäts Klinik Bonn 68 Patienten befragt und die Ergebnisse ausgewertet. Von diesen wurde bei 14 Patienten weniger als 30 cm Ileum reseziert, bei 21 Patienten 30- 80 cm, bei 19 Patienten 80-150 cm und bei 9 Patienten mehr als 150 cm. Bei 5 Patienten wurden 80 cm Jejunum reseziert. 53 (77,9%) der befragten Patienten gaben z. Z. der Entlassung Durchfälle an. Bei 16 Patienten (23,5%) trat postoperativ keine Besserung ein, bei 26 Patiente (38,2%) dauerte die Adaptation 3 Monate bis zu 1 Jahr. Zwischen Resektatlänge und Stuhlfrequenz sowie allgemeinem Beschwerdebild fand sich bei fast allen Gruppen eine Korrelation.
    Notes: Summary To document the clinical symptoms after partial resection of the small intestine 68 patients of a total of 197 patients operated during the period of 1958-1978, Department of Surgery, University of Bonn, were evaluated for their postoperative symptoms. Of the 68 patients 14 had a resection of less than 30 cm of the ileum, 21 patients of 30–80cm, and 9 more than 150cm. Five patients had undergone a resection of 80 cm of jejunum. Of these patients 53 (78%) had diarrhea at the time of discharge from the hospital. A normalisation of the bowel movement appeared after 3 to 12 months in 26 patients (38%),16 patients (24%) experienced no improvement at all. A correlation between the length of intestinal resection and requency of bowel movements as well as general symptoms was found in all groups of patients.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 358 (1982), S. 471-471 
    ISSN: 1435-2451
    Keywords: Ileal resection ; Biliary secretion ; Cholesterol gallstone formation ; Ileumresektion ; biliäre Sekretion ; Cholesteringallensteinbildung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Patienten mit Resektion des terminalen Ileums weisen eine erhöhte Incidenz von Cholesteringallensteinen auf. Zur Aufklärung des Mechanismus der Steinbildung wurde bei 5 Patienten mit Ileumresektion (mehr als 120 cm) und bei 5 Kontrollpersonen die biliäre Lipidsekretion über 24 h gemessen. Die biliäre Sekretion von Gallensäuren (GS), Phospholipiden (PL) und Cholesterin (CH) war bei den resezierten Patienten um 52 %, 53 % bzw. 47 % erniedrigt. Die Reduktion der CH-Sekretion war nicht so ausgeprägt wie die von GS und PL. Aus diesem Grunde war die Galle bei Ileumresezierten 14 h am Tag mit CH übersättigt, im Gegensatz zu 7h bei den Kontrollpersonen (p 〈 0,0s1).
    Notes: Summary Patients with resection of the ileum are at increased risk of forming cholesterol gallstones. In order to investigate the underlying mechanism of stone formation, biliary lipid secretion was measured for 24 h in five patients after ileal resection (more than 120 cm) and five controls. The biliary secretion of bile acid (BA), phospholipids (PL), and cholesterol (CH) in ileal resected patients was reduced by 52%, 53%, and 47%, respectively. The reduction in cholesterol secretion rate was not as much as that of BA and Pl. As a result, the bile in patients with ideal resection was supersaturated with CH for 14h in contrast to 7 h in control subjects (p 〈 0.01).
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 354 (1981), S. 273-279 
    ISSN: 1435-2451
    Keywords: Duodenogastric reflux ; Quantification ; Gastric resection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der duoenogastrische Reflux wurde quantitativ bei den klassischen Magenresektionsverfahren (Billroth II — mit und ohne Enteroanastomose, Billroth I), sowie bei Magengesunden bestimmt. Insgesamt wurden 43 Magenresezierte und 6 Magengesunde untersucht. Die B II-Resezierten ohne Braunsche Enteroanastomose (n = 10) wiesen einen Reflux von 50,4 ± 4,1 % (SEM) der während der Untersuchung sezernierten Gallenmenge auf. Bei den B II-Resezierten mit Braunscher Enteroanastomose (n = 15) betrug der Reflux 21,5 ± 3,7 % (SEM), bei den B I-Resezierten (n =17) 23,1 ± 3,5 (SEM). Die magengesunden Kontrollpersonen (n = 6) wiesen einen Reflux von 0,5 ± 0,4% (SEM) auf.
    Notes: Summary The duodenogastric reflux was measured quantitatively in patients with classic gastric resections (Billroth I, Billroth II with and without enteroanastomosis) as well as in patients without gastric operations. A total of 43 patients with gastric resection and 6 without gastric operation were studied. Patients operated according to B II without Braun's enteroanastomosis (n = 10) had a bile reflux of 50.4 ± 4.1 % (SEM) during the study. Patients having been operated according to B II- with Braun's-enteroanastomosis (n = 15) and those having undergone B I-operation (n = 17) had a duodenogastric reflux of 21.5 ± 3.7 % (SEM) and 23.1 ± 3.5 % (SEM), respectively. In 6 control subjects without gastric operation bile reflux into the stomach averaged 0.5 ± 0.4 % (SEM).
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 259 (1981), S. 990-994 
    ISSN: 1435-1536
    Keywords: NMR ; proton spin-spin relaxation ; styrene-butadienestyrene block copolymer ; rubber crosslink density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Zur quantitativen Erfassung der Vernetzung eines Kautschuks ist es wünschenswert, die Vernetzungsdichte des Netzwerks zu bestimmen. Styrol-Butadien-Styrol Blockcopolymere können als Modellnetzwerke für einen Kautschuk mit einheitlichen Netzbogenlängen angesehen werden. Für die Modellnetzwerke wird die Beziehung zwischen der Protonen Spin-Spin-Relaxationszeit und der Vernetzungsdichte bestimmt. Unterhalb eines kritischen Molekulargewichts (M c = 40 000) des Kautschuks, das der Bildung von Verschlaufungen entspricht, ist die Spin-Spin-Relaxationszeit proportional zur Netzbogenlänge; oberhalb des kritischen Wertes ist sie nahezu unabhängig vom Molekulargewicht des Kautschuks.
    Notes: Summary For a quantitative description of rubber crosslinking it is desirable to determine the crosslink density of the network. Styrene-butadiene-styrene block copolymers can be regarded as model networks for a rubber with uniform chain lengths between the crosslinks. For these model networks the relation between the proton spin-spin relaxation time and the crosslink density is determined. Below a critical value for the molecular weight of the rubber segment (M c = 40 000) which corresponds to the formation of entanglements, the relaxation time is proportional to the crosslink spacing. Above the critical value the relaxation time is almost independent of the molecular weight of the rubber.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 15 (1982), S. 631-634 
    ISSN: 1612-1112
    Keywords: Gas Chromatography ; FID with integrated hydrogenation reactor ; Formaldehyde traces ; Automobile exhaust gases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the gas chromatographic determination of traces of formaldehyde is described. The formaldehyde is detected by means of a modified FID which contains a microreactor inside the jet for the hydrogenation of formaldehyde to methane. Only a slight modification to an ordinary FID is needed with no additional gas tubes and no alteration to the existing detector heater. The additional dead volume and peak broadening is negligible. The system is calibrated by means of a gas generator. The described method is used for determining the content of formaldehyde in the exhaust gases of methanol-driven cars.
    Type of Medium: Electronic Resource
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