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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 550 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Simultaneous temporally and spatially resolved measurements of the phase change and reflectivity of S- and P-polarized femtosecond laser probes are obtained from hot expanded states produced by femtosecond laser heating of a solid aluminum target. The combined set of data provides an integral test of equation-of-state models in a regime up to 10 Mbar and densities of 0.01–1 times solid. The results suggest that target stoichiometry at the few Å level should be considered in the analysis of phase and reflectivity measurements in such experiments. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact grazing-incidence spectrometer was implemented on the Livermore electron beam ion trap facility for spectral measurements in the extreme ultraviolet spectral region. The spectrometer employed a 1200 l/mm grating designed for flat-field focusing and a charge coupled device camera for readout. The instrument was used to measure line emission in the range from 25 to 220 Å with a resolving power as high as 600. The performance and calibration of the instrument is described and spectra from highly charged nitrogen and iron ions are presented. Measurements of the K-shell spectrum of He-like N5+ are presented that confirm earlier wavelength determinations and illustrate the accuracy achievable with the instrument. Our measurement suggests a change in the line identifications of the forbidden He-like N5+ transition 1s2s 3S1→1s2 1S0 and of the Li-like N4+ collisional satellite transition 1s2s2p 2P3/2→1s22s 2S1/2 observed on the Alcator C-Mod tokamak. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 74 (1970), S. 236-240 
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Den nach wöchentlicher Applikation von 1,2-Diemthylhydrazin im Dünn- und Dickdarm der Ratte sich entwickelnden Carcinomen sind Veränderungen an der Schleimhaut vorgeschaltet, die durch eine Entdifferenzierung und Proliferationssteigerung charakterisiert sind. Im Autoradiogramm finden sich dabei nach Applikation von 3-H-Thymidin in der Dickdarmschleimhaut Herde, in denen bei völligem Fehlen der Becherzellen die Proliferationszone bis an die Schleimhautoberfläche heranreicht. Im Dünndarm verbreitert sich die Indifferenzzone über die gesamte Zotte hinweg. Vor allem die Veränderungen am Dickdarm sind in jeder Beziehung denen ähnlich, die man bei der Schleimhautregeneration beobachtet.
    Notes: Summary Weekly s. c. injections of 21 mg 1,2-dimethylhydrazine/kg body weight induced in rats papillomas and carcinomas of the small and large intestine. In 12 of a total of 77 rats adenocarcinomas arose in the large intestine between the 10th and 16 th week after starting the injections. In the same groups 3 carcinomas and 21 papillomas of the small intestine were detected histologically. Autoradiographic investigations after application of 34S-sulphate and 3H-thymidine showed between the 5th and 12 th weeks alterations of the mucosa of the large intestine characterized by a decrease in the number of mucous secreting cells. The differentiation of basal epithelial cells to mucous secreting cells was inhibited. In the same regions the number of DNA synthesizing cells increased, producing an enlargement of the proliferation zone which reached from the bottom of the crypts up to the surface of the mucosa. The labelling index increased 3 fold compared to the normal. Also in the small intestine the “indifferenzzone”, being normally identical with the crypts of Lieberkühn, extended the length of the villi. The epithelial cells of the tips of the villi showed a high proliferating activity. Papillomas developed in those areas closely related to the proliferation activity of the epithelia. As in the large intestine the areas with enlarged proliferation zones showed a loss of cellular differentiation.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1084
    Keywords: Key words: Colon – CT – Three-dimensional CT – Virtual endoscopy – Image processing – Radiation exposure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pig's colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and “fly through” sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 87 (1994), S. 657-667 
    ISSN: 1432-2242
    Keywords: Transposable elements ; Mutation ; Evolution ; DNA repair ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mobile DNAs of the Mutator system of maize (Zea mays) are exceptional both in structure and diversity. So far, six subfamilies of Mu elements have been discovered; all Mu elements share highly conserved terminal inverted repeats (TIRs), but each sub-family is defined by internal sequences that are apparently unrelated to the internal sequences of any other Mu subfamily. The Mu1/Mu2 subfamily of elements was created by the acquisition of a portion of a standard maize gene (termed MRS-A) within two Mu TIRs. Beside the unusually long (185–359 bp) and diverse TIRs found on all of these elements, other direct and inverted repeats are often found either within the central portion of a Mu element or within a TIR. Our computer analyses have shown that sequence duplications (mostly short direct repeats interrupted by a few base pairs) are common in non-autonomous members of the Mutator, Ac/Ds, and Spm(En) systems. These duplications are often tightly associated with the element-internal end of the TIRs. Comparisons of Mu element sequences have indicated that they share more terminal components than previously reported; all subfamilies have at least the most terminal 215 bp, at one end or the other, of the 359-bp Mu5 TIR. These data suggest that many Mu element subfamilies were generated from a parental element that had termini like those of Mu5. With the Mu5 TIRs as a standard, it was possible to determine that elements like Mu4 could have had their unusual TIRs created through a three-step process involving (1) addition of sequences to interrupt one TIR, (2) formation of a stem-loop structure by one strand of the element, and (3) a subsequent DNA repair/gene conversion event that duplicated the insertion(s) within the other TIR. A similar repair/conversion extending from a TIR stem into loop DNA could explain the additional inverted repeat sequences added to the internal ends of the Mu4 and Mu7 TIRs. This same basic mechanism was found to be capable of generating new Mu element subfamilies. After endonucleolytic attack of the loop within the stem-loop structure, repair/conversion of the gap could occur as an intermolecular event to generate novel internal sequences and, therefore, a new Mu element subfamily. Evidence supporting and expanding this model of new Mu element subfamily creation was identified in the sequence of MRS-A.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 77 (1989), S. 844-850 
    ISSN: 1432-2242
    Keywords: Evolution ; Restriction fragment length polymorphism ; Grasses ; Maize ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The structure and organization of the ribosomal DNA (rDNA) of sorghum (Sorghum bicolor) and several closely related grasses were determined by gel blot hybridization to cloned maize rDNA. Monocots of the genus Sorghum (sorghum, shattercane, Sudangrass, and Johnsongrass) and the genus Saccharum (sugarcane species) were observed to organize their rDNA as direct tandem repeats of several thousand rDNA monomer units. For the eight restriction enzymes and 14 cleavage sites examined, no variations were seen within all of the S. bicolor races and other Sorghum species investigated. Sorghum, maize, and sugarcane were observed to have very similar rDNA monomer sizes and restriction maps, befitting their close common ancestry. The restriction site variability seen between these three genera demonstrated that sorghum and sugarcane are more closely related to each other than either is to maize. Variation in rDNA monomer lengths were observed frequently within the Sorghum genus. These size variations were localized to the intergenic spacer region of the rDNA monomer. Unlike many maize inbreds, all inbred Sorghum diploids were found to contain only one rDNA monomer size in an individual plant. These results are discussed in light of the comparative timing, rates, and modes of evolutionary events in Sorghum and other grasses. Spacer size variation was found to provide a highly sensitive assay for the genetic contribution of different S. bicolor races and other Sorghum species to a Sorghum population.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0649
    Keywords: PACS: 42.65.Re; 52.40.Nk; 41.85.Ew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We have successfully developed a laser system to produce pulses with a wavelength centered at 800 nm, energies above 15 J, temporally compressed to 75 fs and focused to power densities beyond 1021 W/cm2. Enabling technologies include chirped-pulse amplification (CPA), 10 cm aperture Ti:Al2O3 crystals, large diffraction gratings, and an energetic Nd:glass laser for pumping the final two amplifiers. Measurements of the compressed pulse spectrum, frequency resolved optical gating (FROG) diagnostic, and focal spot are presented. We have also investigated and developed a technique for suppression of transverse parasitic lasing in large-aperture Ti:sapphire crystal amplifiers.
    Type of Medium: Electronic Resource
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