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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 80 (1958), S. 2659-2662 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 69 (1947), S. 1410-1415 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 157 (2000), S. 435-448 
    ISSN: 1420-9136
    Keywords: Key Words: Attenuation, surface contamination, partially saturated cracks, dime-shaped.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —We have examined the effect of surface contamination on the attenuation and stiffness of compressional seismic waves in artificial cylindrical glass cracks that are partially saturated with water. The compression of the gap perpendicularly to its plane reduces the gap volume and forces the water to redistribute within the gap (conservation of volume of an incompressible liquid). On clean surfaces, the water can flow without significant resistance across the glass. This leads to a very low and almost constant attenuation over a wide frequency range (approx. 3 mHz to 10 Hz), while the sample stiffness is constant. In the case of propanol contaminated surfaces, both the attenuation and the stiffness are considerably higher than in the clean case, and display a considerable frequency dependence. Both effects can be explained with the Restricted Meniscus Motion Model. In this model, the redistribution of the liquid in the gap first leads to a change (increase) of the contact angle. The change of the meniscus curvature results in an increase of the pressure in the liquid and thus to a stiffening of the sample. When the resistive force, that prevents the contact line from sliding along the surface, is finally overcome, the contact line starts moving across the contaminated surface. The motion against the resistive force dissipates energy and increases the attenuation. The calculated data are in good agreement for both the clean and the contaminated case; the model parameters fall in the range that was established by independent experiments (e.g. ).
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Kipptisch ; Autoregulation ; Doppler–Sonographie ; Säuglinge ; Halothannarkose ; Keywords Tilting test ; Autoregulation ; Infants ; Doppler sonography ; Halothane anesthesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Halothane causes impairment of cerebrovascular reactivity and autoregulation. We used transcranial Doppler sonography (TCD) to investigate the reaction patterns of cerebral blood flow velocities (CBFV) during a standardized orthostatic maneuver after premedication and during halothane anesthesia in infants. After premedication orthostasis led to no significant changes in CBFV. During halothane anesthesia CBFV was significantly higher than after premedication, and orthostasis induced a significant decrease in CBFV compared to values obtained in horizontal position. Heart rate and mean blood pressure were significantly lower than before medication during halothane anesthesia. The observed changes in CBFV during halothane anesthesia represent a characteristic pattern of impaired cerebral autoregulation. The changes in CBFV and heart rate demonstrate that neither systemic nor cerebral hemodynamics compensate for hydrostatic inducement during halothane anesthesia. The tilting test is a useful tool for determining cerebral autoregulation capacity in infants.
    Notes: Zusammenfassung Halothan führt zu einer Hemmung der Vasomotorenreaktivität und verursacht so eine Einschränkung der zerebralen Autoregulation. Wir untersuchten bei Säuglingen mittels transkranieller Dopplersonogaphie (TCD) die Reaktionsmuster der zerebralen Blutflussgeschwindigkeiten (zBFG) im Rahmen eines standardisierten Orthostasetests (Kipptischtest) unter Prämedikation und in Halothannarkose. Unter der alleinigen Prämedikation kam es in vertikaler Körperposition (Orthostase) zu keinen signifikanten Veränderungen der zBFG. Unter Halothannarkose kam es bereits in horizontaler Körperposition im Vergleich zur Prämedikation zu einem signifikanten Anstieg der zBFG. In Orthostase kam es im Vergleich zu den Ausgangswerten in horizontaler Lage zu einem signifikanten Abfall der zBFG. Im Vergleich zur Prämedikation waren unter Haloththannarkose das Niveau der Herzfrequenz und der mittleren Blutdruckwerte signifikant niedriger. Die Veränderungen der zBFG und der Herzfrequenz zeigen, dass unter Halothannarkose sowohl systemische als auch zerebrale Kreislaufparameter nicht kompensatorisch auf die Orthostase als hydrostatischen Provokationsreiz reagieren. Die beschriebenen Veränderungen der zBFG im Orthostasetest während der Halothannarkose stellen ein typisches Muster dar, das bei eingeschränkter Autoregulation zu erwarten ist. Der Orthostasetest ist ein brauchbarer Test zur Beurteilung der zerebralen Autoregulation bei Säuglingen.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 243 (1996), S. 171-174 
    ISSN: 1432-1459
    Keywords: Brainstem function ; Obstructive sleep apnoea ; Brainstem lesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Phasic inspiratory genioglossus activity prevents pharyngeal airway collapse in healthy subjects during sleep and is diminished or absent in obstructive sleep apnoea syndrome (OSAS), thus leading to pharyngeal obstruction. Case reports of OSAS after pontomedullary lesions indicate that impaired inspiratory genioglossal activity may result from brainstem lesions. We therefore investigated brainstem functions in 18 awake patients with OSAS using brainstem auditory evoked potentials, blink reflex, masseter reflex, masseter inhibitory reflex (in 11 of 18 patients), magnetic evoked potentials of the tongue and electrooculography with vestibular testing. Fifteen of 18 patients showed no electrophysiological abnormalities. One patient had a left pontine and two patients a bilateral pontomesencephalic lesion, although a causal connection with OSAS was not conclusively confirmed. Our results do not support the assumption of a relevant structural brainstem lesion in OSAS patients with normal neurological findings.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract Modern microsystem application is concentrated on the development of microstructured sensors and actuators in integrated devices. Examples of that approach are microoptical components for endoscopic surgery, sensors and micropumps in integrated liquid analysers for pollution measurements. Often microsystems replace normal systems like commercially available piston pumps by silicon made liquid pumps in the hope of reducing costs but there is a lack of finding new applications. In contrast our approach of combining special developed microcompartments constructed with transparent membranes or microsieves and microdosing systems based on the ink jet principle together with optical devices like CCD cameras allow to overcome a real bottleneck in the new field of evolutionary biotechnology, the problem of screening a huge number of samples at a reasonable price. The goal of this approach is to design new molecules like enzymes by means of Darwinian evolution i.e. mutation and selection. In applying the selection principle to self amplifying entities like cell populations, viruses or self-replicating molecules under controlled selection pressures there is an absolute need to process large numbers of these entities in parallel. Preferentially this can be done in arrays of different microstructured compartments. The selection process is designed that it leads to products which are optimized in regard of specific applications. Within the scope of this approach chemical products are deterministically synthesized in spatially adressable compartments by multihead microdrop systems.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract Photolithographic preparation of thin films and stacks of them were combined with anisotropic silicon etching and free standing film technology in order to realize three dimensional micro components for studies in detection and optimization of biomolecules. A polymer based SFM sensor was developed and tested in the measurement of thin film roughness and in the detection of holes in molecular films as well as in the detection of single DNA molecules. This “novolever” shows surprisingly high mechanical stability and provides high resolution SFM images of sensible molecules. Experimental arrangements of miniaturized chemical parallel processing for combinatorial and evolutionary synthesis strategies including silicon micro compartment arrays with free standing optical membranes and thin film filters have been proposed and the manufacturing of micro compartment arrays is described.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract  Microsystems recently have been introduced as tools for screening in modern chemistry, biochemistry and biology. It has been shown that new microsystems can be implemented in the biomedical laboratory by using the microsystemic approach for the sample carrier – the miniaturized microtiter plate (“the nanotiter plate”) – or the production of nanodroplets with ink jetters and to integrate those systems in macrodevices like xyz tables and detection devices like CCD-cameras. We show in this paper that decisive problems of the approach – the evaporation problem and the problem of chemical/biochemical/biological compatibility of the assays and the used materials can be solved successfully. It is possible to realize chemical synthesis in miniaturized flow systems and to perform isothermal amplification of RNA in silicon wafers. Furthermore real high throughput screening with in vivo systems can be performed and all relevant parameters as evaporation, pipetting and detection can be controlled on reasonable time scales.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 20 (1996), S. 210-217 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In order to investigate the temporal behavior of dynamic flow processes, a movie version of particle image velocimetry (PIV) with a high framing capability has been developed. The experimental setup includes a copper vapor laser capable to produce pulse sequences with more than 100 pulses with a repetition rate of up to 30 kHz and a rotating drum camera to record the Mie scattering signals from the particles seeded to the flow. With this setup, image sequences with a number of consecutive images (40–70 depending on the image size) of a dynamic process can be taken on high resolution 36 mm film. To evaluate the 2-dimensional velocity vector fields, an algorithm based on the crosscorrelation of subareas in consecutive images has been developed and optimized in terms of computing time. The technique was applied to resolve the instationary flow field in a single cylinder spark ignition (SI) engine during the compression stroke.
    Type of Medium: Electronic Resource
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