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1.
H. Ant 《Plant Ecology》1969,18(1-6):374-386
Zusammenfassung Die Pflanzengesellschaften werden als objektive Einheiten der Erdoberfläche angesehen, die als Grundlage für biosoziologische Untersuchungen dienen können. Die verschiedenen bislang angewandten Untersuchungsverfahren zur quantitativen Erfassung des Tierartenbestandes eines einheitlichen Gebietes wereden angeführt und erörtert. Die eigenen Untersuchungen wurden in Probeflächen des Melico- und Carici-Fagetum durchgeführt. Dabei wurden mehrere Probequadrate von 25×25 cm abgesteckt und zu einer Probefläche zusammengefaßt. Zur Angabe der Frequenz und Abundanz wird ein Klassensystem benutzt (+, 1 bis 5). In Waldgesellschaften sind mindestens 8 Probequadrate erforderlich. Der Vergleich mehrerer einheitlicher Bestände ergibt die Konstanz (I bis V). Für das Carici-Fagetum lassen sich Abida secale, Clausilia parvula und Iphigena plicatula als Kenn-Arten ausscheiden. Die Artenzahl ist im Melico-Fagetum geringer. Einige Arten können evtl. als geographische Differentialarten angesehen werden.
Summary The plant associations are considered to be objective units of the earth surface which may be a basis for biosociological researches. The different methods used for quantitative studies of the animal species of a homogeneous area are recorded and discussed. Own studies of the Melico-Fagetum and Carici-Fagetum have been carried out in northwestern Germany. Several sample squares of 25×25 cm are marked out and treated as a whole called sample area. Frequency and abundancy are represented by five classes (1 to 5). In wood communities 8 sample squares are necessary. The constancy means the frequency within several homogeneous sites (I to V). Thus it was found that the Carici-Fagetum is characterized by Abida secale, Clausilia parvula and Iphigena plicatula as euconstant species. The number of species is less in the Melico-Fagetum. Some species may be defined as geographically differentiating species.相似文献
2.
Rui L. Mendes Helena L. Fernandes José A.P Coelho Joaquim M.S Cabral António M. F. Palavra Júlio M. Novais 《Journal of applied phycology》1994,6(3):289-293
Samples of the microalgaBotryococcus braunii were submitted to supercritical fluid extraction with carbon dioxide at 40 °C and pressures of 12.5, 20.0 and 30.0 MPa. The extraction yield and the fraction of the hydrocarbons in the extracts both increased with pressure and at 30 MPa these compounds were obtained rapidly. This behaviour is associated with the localization of the hydrocarbons outside the cell wall. In the extracts, which are fluid, golden and limpid, chlorophyll and phospholipids were not detected.Author for correspondence 相似文献
3.
Flavio Alexandre Carvalho Natália Valadares de Moraes Antônio Eduardo Miller Crotti Eduardo José Crevelin André Gonzaga dos Santos 《化学与生物多样性》2023,20(9):e202300492
Casearia species are found in the America, Africa, Asia, and Australia and present pharmacological activities, besides their traditional uses. Here, we reviewed the chemical composition, content, pharmacological activities, and toxicity of the essential oils (EOs) from Casearia species. The EO physical parameters and leaf botanical characteristics were also described. The bioactivities of the EOs from the leaves and their components include cytotoxicity, anti-inflammatory, antiulcer, antimicrobial, antidiabetic, antioxidant, antifungal, and antiviral activities. The main components associated with these activities are the α-zingiberene, (E)-caryophyllene, germacrene D, bicyclogermacrene, spathulenol, α-humulene, β-acoradiene, and δ-cadinene. Data on the toxicity of these EOs are scarce in the literature. Casearia sylvestris Sw. is the most studied species, presenting more significant pharmacological potential. The chemical variability of EOs components was also investigated for this species. Caseria EOs have relevant pharmacological potential and must be further investigated and exploited. 相似文献
4.
Xavier Isaac M. de Pádua Antônio Moraes Fernando De Miranda-Neto J. A. 《Molecular Engineering》1997,7(3-4):283-291
Starburst dendrimers are highly branched oligomers. A rigid dendritic hydrocarbon, C1134H1146, has recently been synthesized. It consists of 94 phenylacetylene units displayed in a self-similar two-dimensional skeleton
isomorphous to the three-coordinated Bethe lattice. The three-dimensional representation of phenylacetylene dendrimer shows
a globular architecture with large voids and niches in its interior, characteristic of hyperbolic surfaces. This work investigates
the geometrical scaling behavior of this starburst dendrimer using the symmetry properties of a Bethe lattice embedded in
the hyperbolic plane. The results for C1134H1146 provide its density profile and an upper bound for its macromolecular size.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
6.
Marden A. de Alvarenga Raimundo Braz Fo Otto R. Gottlieb João P. de P. Dias Aderbal F. Magalhães Eva G. Magalhães Gouvan C. de Magalhães Mauro T. Magalhães José G.S. Maia Raquel Marques Anita J. Marsaioli Antônio A.L. Mesquita Anselmo A. de Moraes Alaide B. de Oliveira Geovane G. de Oliveira Gentil Pedreira Sebastião K. Pereira Sonildes L.V. Pinho Celira C. Santos 《Phytochemistry》1978,17(3):511-516
Wood samples, infested by fungi during storage, were shown to contain, besides the known 5-methyl-mellein, additional (3R)-8-hydroxy-3-methyl-3,4-dihydroisocoumarins substituted by 7-methyl, 5-formyl, 5-carboxy, 5-hydroxy, 5-methoxy, 6-methoxy-5-methyl and 6,7-dimethoxy-5-methyl groups, as well as 6-formyl-7-hydroxy-5-methoxy-4-methylphthalide. Several 2-methylchromanones were synthesized in order to show that this class of compounds can be distinguished from 3-methyl-3,4-dihydroisocoumarins by MS. 相似文献
7.
A NMR and magnetic susceptibility study of the oxidized and reduced states of three different oligomers (forms) of a [4Fe-4S] ferredoxin protein from Desulphovibrio gigas, FdI, FdI′, and FdII was carried out. FdI and FdI′ are different trimers and FdII a tetramer of the same basic subunit. A probable assignment of the contact shifted resonances is indicated. Since the temperature dependences of the contact shifted resonances associated with each [4Fe-4S] are not all similar a delocalized model for the spin densities on the 4Fe does not apply. The exchange rate between oxidized and reduced states is slow on the NMR time scale. The three oligomers are not magnetically equivalent. Using the “three state hypothesis” terminology it is shown that FdIox is predominantly in the C2? state and changes upon reduction into the C3? state, while FdIIox is in the C? state and changes into the C2? state. FdI′ does not easily fit into this classification. This study shows a similarity of magnetic behaviour between FdI and bacterial ferredoxins (e.g. Bacillus polymyxa) and between FdII and HiPIP from Chromatium sp.. The influence of the quaternary structure on the stabilization of the different oxidation states of ferredoxins as well as on their redox potentials is discussed. 相似文献
8.
Mireille Bruschi E.Claude Hatchikian Jean Le Gall JoséJ.G. Moura António V. Xavier 《BBA》1976,449(2):275-284
Three forms of ferredoxin FdI, FdI′, and FdII have been isolated from Desulfovibrio gigas, a sulfate reducer. They are separated by a combination of DEAE-cellulose and gel filtration chromatographic procedures. FdI and FdI′ present a slight difference in isoelectric point which enables the separation of the two forms over DEAE-cellulose, while FdII is easily separated from the two other forms by gel filtration. The three forms have the same amino acid composition and are isolated in different aggregation states. Molecular weight determinations by gel filtration gave values of 18 000 for FdI and FdI′ and 24 000 for FdII, whereas a value of 6000 is determined when dissociation is accomplished with sodium dodecyl sulfate. The electronic spectra are different and their ultraviolet-visible absorbance rations are 0.77, 0.87 and 0.68 respectively for FdI, FdI′ and FdII. Despite these differences, the physiological activities of the three forms are similar as far as the reduction of sulfite by molecular hydrogen is concerned. 相似文献
9.
Antônio A. Lins Mesquita Wanderley Gonçlves De Oliveira Rosa M. Taveira Neiva Otto R. Gottlieb 《Phytochemistry》1975,14(3):803-806
The wood of Tovomita pyrifolium (Guttiferae) contains the novel tovopyrifolins A [1,6-dihydroxy-7-methoxy-5-prenyl-6′,6′-dimethylpyrano (2′,3′:3,2)xanthone], B (1,5-dihydroxy-3,4-dimethoxyxanthone) and C (1,3,5-trihydroxy-2-methoxyxanthone) and also the known tovophyllins A and B [structure revised to 1,6-dihydroxy-5-prenyl-6′, 6′-dimethylpyrano(2′,3′:3,2)-6″,6″-dimethylpyrano(2″,3″:7,8)xanthone]. 相似文献
10.
The in vivo spontaneous release of enkephalin in the globus pallidus of the rat increases from noon to evening by 100%; during this period the local release of exogenous gamma-aminobutyric acid (GABA) decreases by 60%. These diurnal rhythms are more marked in the K+-stimulated release: enkephalin-induced output increases 6-fold while GABA decreases 10-fold during the afternoon and evening hours. Since pallidal enkephalin and GABA are involved in the control of locomotor activity we suggest that these rhythms may be linked to the circadian changes of activity in the rat. 相似文献