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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 4587-4593 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 1 (1950), S. 237-247 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Summary The travelling-wave tube (T. W. T.) is recomputed by means of an equivalent circuit giving the characteristic impedance for purposes of comparison with the klystron and the triode. With the klystron and the T. W. T. a shot effect is induced in the amplifier input, but not with the triode, so that increasing the transconductance of the two former tubes does not result in a reduction of the noise figure as with the triode. For the same beam current the noise figure of the T. W. T. and the klystron are approximately the same. The T. W. T. is, however, superior to the klystron in that, for the same beam length, the gain is greater, due to the fact that it increases exponentially for the former and linearly for the klystron. It is therefore concluded that it should be possible considerably to improve the signal-to-noise ratio of the klystron-type of amplifier by suitably increasing the beam length (e. g. by magnetic means). An advantage accruing would be that the input and output are decoupled; in the case of the T. W. T. this leads to oscillation if the helix is not matched so as to avoid reflections.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 2 (1923), S. 1742-1744 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 148 (1985), S. 291-312 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Boraginaceae ; Microparacaryum gen. nov. ; Paracaryum ; Mattiastrum ; Taxonomy ; distribution maps ; heteromericarpy ; fruit polymorphism ; Flora of Western Asia (Turkey, U.S.S.R., Iran, Iraq, Afghanistan, Pakistan)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microparacaryum (M. Pop. exH. Riedl)Hilger & Podlech is described as a new genus of theBoraginaceae-Cynoglosseae. It comprises the annual species hitherto included inParacaryum (DC.)Boiss. andMattiastrum (Boiss.)Brand. Distribution maps are given for all 3 genera.Microparacaryum consists of two species,M. salsum (Boiss.)Hilger & Podlech (M. s.) andM. intermedium (Fresen.)Hilger & Podlech (M. i.). ParticularlyM. i. is a very variable species, and most of the species formerly recognized belong here. Scattered all over the range of the genus, plants occur with nutlets exhibiting flat or incurved marginal wings, often in mixed populations. This fruit polymorphism is taxonomically treated by recognizing “formae”. In addition, the following new infraspecific taxa and combinations are described:M. i. var.intermedium formaparacaryoides Hilger & Podlech,M. i. var.stellatum (H. Riedl)Hilger & Podlech,M. i. var.stellatum formamattiastroides Hilger & Podlech,M. s. formamattiastroides Hilger & Podlech.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 221 (2000), S. 253-258 
    ISSN: 1615-6110
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 29 (1974), S. 109-114 
    ISSN: 1573-5052
    Keywords: Aeluropus lagopoides ; Cyperus laevigatus ; Maharlu-Salzsee (Iran) (Maharlu salt lake) ; Potamogeton pusillus ; Salicornia europaea ; Salzböden (saline soils) ; Salzkonzentration (salt concentration) ; Strandvegetation (salt marsh vegetation) ; Süßwasserquellen (fresh water sources) ; Vegetationszonierung (vegetation zonation)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Description de la répartition des zones de végétation autour de trois sources d'eau douce situées sur les bords du lac salé de Maharlu au Sud de l'Iran. La succession spatiale des familles végétales fait fonction de la diminution de la salinité à partir du bord du cône deltaique jusqu'aux sources. Sur les sols salins du lac de Maharlu domineJuncus maritimus. Là où s'exerce l'influence de l'eau douceJuncus maritimus est en régression et c'estAeluropus lagopoides qui prend sa place. Près des sources elles-mêmes s'installent des espèces qui sont tributaires de l'eau douce, par exemplePotamogeton pusillus etSpirogyra fluviatilis. Entre les effluents et la ligue d'eau du lac domineCyperus laevigatus. On peut distinguer là trois zones intermédiaires: près des sources apparaissent des espèces fortement tributains de l'eau douce commeSpirogyra fluviatilis. Puis viennent des groupes compacts deChara tomentosa, qui regressent au fur et à mesure qu'on se rapproche du large. Avant la zone deSalicornia, composée en parti d'espèces deSalicornia europaea et deSpergularia marina, baignées d'eau marine, on ne trouve plus queCyperus laevigatus etMougeotia cf.crassa ainsi que quelques algues bleues.
    Notes: Summary Vegetation zonation around three fresh water sources along the salt lake Maharlu, S. Iran, is described. Spatial distribution of vegetation types is a function of the decrease in salinity within the delta-like area between lake border and sources.Juncus maritimus dominates on the saline soils of the lake shore. On places under influence of fresh waterJuncus maritimus is replaced byAeluropus lagopoides. Near the sources species from fresh water conditions establish, e.g.Potamogeton pusillus andSpirogyrafluviatilis. Between the drainage streams of the sources and the shorelineCyperus laevigatus dominates. Here three subzones can be distinguished. Nearest to the sources species likeSpirogyra fluviatilis are found, further away a compact mat ofChara tomentosa. In front of theSalicornia zone withSalicornia europaea andSpergularia marina onlyCyperus laevigatus withMougeotia cf.crassa and blue algae occur.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1615-6110
    Keywords: Musci ; Hypopterygiaceae ; Lopidium concinnum ; Palaeoaustral taxon ; genetic similarity ; chloroplast DNA ; trnTUGU —trnLUAA intergenic spacer ; trnLUAA intron ; trnLUAA —trnFGAA intergenic spacer ; non-coding region ; stenoevolutionary taxon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolutionary relationship between disjunct populations of the palaeoaustral moss taxonLopidium concinnum (Hypopterygiaceae) from New Zealand and southern South America were studied using non-coding chloroplast DNA sequences. No or only slight changes could be observed within the sequences oftrnTUGU —trnLUAA 5′exon intergenic spacer,trnLUAA intron andtrnLUAA 3′exon —trnFGAA intergenic spacer. This indicates nearly no genetic divergence between extant New Zealand and Chilean populations, i.e. no significant differing pathways of evolution within the 80–60 million years of disrupted areas with interrupted gene flow. Molecular data support the idea of an old Gondwanan relict species of stenoevolutionary character. Ecological data on short-range dispersal strengthen this assessment.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-193X
    Keywords: Cycloadditions ; Dehydrochlorination ; Cycloheptenones ; Tropones ; Tropolones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Pentachloroacetone (1) reacts with several conjugated dienes in the presence of sodium trifluoroethoxide/trifluoroethanol to form cycloadducts of a tetrachlorooxyallyl intermediate 6, mainly in the [4+3] mode. Representative [4+3] cycloadducts, i.e. α,α,α′,α′-tetrachlorocycloheptenones 9, have been dehalogenated and dehydrohalogenated, furnishing α,α′-dichlorotropones 15 in high yields.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 22 (1939), S. 673-683 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 28 (1998), S. 231-240 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Sengende Sonnenglut, heftige Sandstürme, Kälte bei Nacht und extremer Wassermangel, so stellen wir uns Wüsten vor. Es sind lebensfeindliche Räume, in denen Moose, die wir im allgemeinen als an Feuchtigkeit angepaßte Organismen kennen, denkbar schlechte Lebensbedingungen vorfinden. Aufgrund der extrem hohen Sonneneinstrahlung und dem Fehlen von Wasser galten Trockenwüsten daher als an Moosen verarmte Grenzlebensräume (Abbildung 1).Unsere eigenen Forschungen der letzten zehn Jahre im altweltlichen Trockengürtel (Judäische Wüste, Wadi Arava/Jordanien, zentrales Saudi Arabien [5-10]) lassen die Moosflora der Wüsten aber in einem neuen Licht erscheinen. Es gibt hier eine ganze Reihe trockenadaptierter, oft nur einige Millimeter großer Spezialisten, die aufgrund der Selektion spezieller morphologischer, anatomischer und ökophysiologischer Differenzierungen ein hohes Evolutionspotential besitzen und eigenständige, oft nur lokal verbreitete (endemische) Arten hervorgebracht haben. Diese sind am Aufbau charakteristischer Moosgesellschaften beteiligt (Abbildung 2), die sich durch spezifische Standortbedingungen und eine konstante Artengarnitur auszeichnen.Die überraschende Vielfalt und Differenzierung in der Moosflora der Wüsten führte uns zu der zentralen Frage: Welche Mechanismen und Lebensstrategien sind es, die Wüstenmoosen die Konstitution verleihen, um sich unter solch lebensfeindlichen Bedingungen behaupten zu können?
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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