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  • 1995-1999  (8)
  • 1985-1989  (6)
  • 1970-1974  (2)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 3350-3352 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High-resolution commercial photomasks and x-ray masks are at present manufactured by a multistep process which involves the use of etching. This route imposes a limitation on the resolution that can be achieved. We describe here a new approach to the fabrication of x-ray masks involving the use of organometallic compounds which undergo direct conversion to metal under the influence of electron beam irradiation. This approach permits fabrication of both x-ray masks and extreme ultraviolet masks in essentially a single processing step. The attainable resolution is unaffected by any limitation incurred by etching processes and is dependent only on such factors as electron scattering and electron beam diameter. We describe here the production of a gold x-ray mask, which was used in conjunction with a compact laser plasma source to demonstrate the lithographic process. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 40 (1986), S. 311-336 
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 12 (1989), S. 0 
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Blindness developed in Atlantic menhaden, Brevoortia tyrannus (L.), within 4 weeks of captivity in an indoor open culture system. Ophthalmoscopic changes indicative of retinal degeneration were substantiated by the absence of retinal electrical activity as measured by conventional electroretinography. Results of histological evaluation suggest that photo-receptor degeneration, occurring initially in the rods of the central retina, was the primary abnormality. With chronicity, all retinal layers degenerated, and marked pigment proliferation developed. Other pathological changes included uveal vascular engorgement, vitreal and anterior chamber haemorrhage, and cataracts. With the exception of dermal hyperpigmentation, no systemic abnormalities were consistently observed. Phototoxicity is the suspected cause of this degenerative retinopathy.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 323-323 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 36 (1974), S. 275-303 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A pathway through the system of branching in the respiratory region of the lung is modelled by a circular cylinder, closed at one end, with partitions which define the component respiratory units. In this model the transport of O2 during inspiration, generated by diffusion is compared with that produced by diffusion together with convection and the importance of convection in the respiratory region in promoting oxygen uptake at the alveolar wall is discussed. For this discussion it is only necessary to consider inspiration. The equations are solved numerically for flow rates of 10, 85 and 200 liters/min. O2 uptake at the wall and curves of constant O2 concentration are shown to illustrate the influence of convection. It is found that after a 2 sec inspiration from an O2 tension of 98 mm Hg and a lung volume of 2300 ml, convection is about 12 per cent as important as diffusion at a flow rate of 85 liters/min, whereas at 10 liters/min convection is only about 0.4 per cent as important as diffusion.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 26 (1970), S. 1206-1207 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Da Guanidinosuccinsäure in der Urämie akkumuliert, wurde angenommen, dass dieses Stoffwechselprodukt bei Niereninsuffizienz die bekannte Glukoseintoleranz verursachen könnte. In-vitro-Versuche am Rattenzwerchfell haben diese Hypothese jedoch nicht bestätigen können, da Guanidinosuccinsäure in der Konzentration von 3 mg/100 ml keinen Einfluss auf die basale oder insulinstimulierte Glucoseaufnahme durch dieses Gewebe zeigte.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The diet of the collembolan Gomphiocephalus hodgsoni was investigated by microscopic examination of the contents of 197 faecal pellets and 32 guts collected at Cape Geology, Victoria Land, Antarctica. Animals came from nine contrasting microhabitats, ranging from mineral soils to bryophyte cushions. Thirty-two different types of ingested material were recognised. Detritus, filamentous cyanobacteria, eukaryotic microalgae and fungal hyphae were the most frequent. There were marked contrasts between individuals collected from different microhabitats, which probably reflected food availability. There was some selectivity in that neither living moss tissue nor the macroscopic chlorophyte alga Prasiola crispa was encountered in faeces or guts, despite their being abundant in some microhabitats. A comparison of active and inactive animals showed the latter to have a significantly higher proportion of empty guts and of guts containing fat globules.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 313 (1985), S. 821-822 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] REPORTS by Knight and Scrutton1 and from our laboratory2 have shown that thrombin enhances the sensitivity to Ca2+ of the secretion of serotonin from permeabilized platelets. This effect was mimicked by adding a synthetic diacylglycerol, loleoyl-2-acetylglycerol1, and was closely associated with an ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1106
    Keywords: Fornix ; Cingulate cortex ; Hippocampus ; Spatial memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study, together with a parallel study in rats (Markowska et al. 1988), attempted to relate the effects of hippocampal-system damage on similar tasks in both rats and monkeys. Not only were monkeys given a task (Experiment 1) which was of the sort usually used with rats, but in the companion study rats were given tasks (Experiment 2) like those usually used with monkeys. Experiment 1 examined the performance of rhesus monkeys with hippocampal-system damage on a spatial working memory task. Monkeys were trained preoperatively on delayed nonmatching-to-sample in a T-maze, placed into groups matched for their preoperative learning scores, and then received one of three treatments: 1) transection of the fornix; 2) ablation of the cingulate cortex; or 3) a sham operation. Monkeys with fornix transection were severely and significantly impaired, but monkeys with cingulate cortical ablations were not significantly impaired, relative to the controls. The results demonstrate that monkeys with fornix transection are severely impaired on a spatial working memory task requiring locomotion and, taken together with earlier work, suggest that the effect of fornix transection in both rodents and nonhuman primates is at least qualitatively similar (see Markowska et al. 1988). Experiment 2 assessed the role of the fornix and cingulate cortex in three conditional tasks in which the monkeys were provided with various spatial cues to indicate which one of two objects was rewarded. Both experimental groups were unimpaired, relative to the control group, on all three tasks, indicating that fornix transection does not produce a general impairment in place learning.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 142 (1999), S. 1-8 
    ISSN: 1432-2072
    Keywords: Key words Scopolamine ; Covert orienting ; Attention ; Monkey ; Reaction time ; Working memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cholinergic agonist nicotine facilitates visuospatial attention shifting, but the role of muscarinic cholinergic drugs in this behavior is unclear. In order to establish the generality of cholinergic action in attention shifting, we administered the muscarinic antagonist scopolamine to two rhesus monkeys trained to perform a cued target detection (Posner) task. In this task, monkeys signaled the detection of a peripheral visual target by releasing a switch and their reaction times were measured. The location of the target’s appearance was preceded by a cue that was either valid (target and cue in the same spatial location), invalid (target and cue to opposite hemifields), spatially uninformative (cues in both hemifields, target to one hemifield), or omitted altogether. Scopolamine produced a dose-dependent increase in all reaction times and a decrease in accuracy. The slowing was most prominent for valid cues in either visual field. However, slowing did not occur in trials whose cues lacked spatial information, or in tasks in which attention was directed to events at the fixation point, whether or not peripheral distractors were present. These results provide additional support for the hypothesis that acetylcholine plays a key role in reflexive attention shifting to peripheral visual targets.
    Type of Medium: Electronic Resource
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