首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
In Mesogea, the Harpoceratinae were known asearly as the end of the Lower Carixian. They later reached the sub-boreal province through the Alps or the South of the Iberic Peninsula. The analysis of the populations met in four crosssections of the Lower Domerian (Causses, Mâconnais, Franche-Comté, Portugal) showed the settling down of the Protogrammoceras isseli group that set up and evoluated in a similar way in the different areas in spite of a certain originality.On the one hand, it gave the cladogenetic groupP. monestieri-nitescens by diminution of the ribing density, strengthening of the ribs and simplification of the suture.On the other hand, a slower evolution give, near the end of the Stokesi zone, P. normanianum in the Paris Basin and in Burgundy, and P. lusitanicum in Portugal. At the same time, a new invader, P. celebratum, arrived in the Causses (and in Portugal).  相似文献   

2.
3.
Melezitose [O-α-d-glucopyranosyl-(1→3)-β-d-fructofuranosyl α-d-glucopyranoside] monohydrate crystallizes in two polymorphic forms (I and II). The structure of form II, studied by X-ray crystallography, shows an orthorhombic cell having a 7.135 (4), b 15.362 (8), c 19.134 (8) Å, space group P212121, and Z 4. The structure, solved by direct methods, was refined to a final value of R 0.045. The molecule of form II seems to be more constrained by its crystalline environment than that of form I. These constraints imply not only little variations in glycosidic bonds, but also a change of conformation for the furanose ring, and a perceptible deformation of the sucrose pyranose ring. This study gives an example of estimation of oligosaccharide molecular-flexibility.  相似文献   

4.
5.
J. Rey  M. Bilotte  B. Peybernes 《Geobios》1977,10(3):369-393
The marine Albain from Estremadura is splited up into four Orbitolinidae zones, adjusted to biostratigraphic scales from mesogean province: zone with Orbitolina (Mesorbitolina) minuta (lower to middle Albian); zone with Neorbitolinopsis conulus (base of upper Albian); zone with Orbitolina (Orbitolina) concava (top of upper Albian) and zone with Orbitolina (Orbitolina) duranddelgai (Vraconian). The vertical extension of the main fossils is replaced in the framework of these zones. The most interesting species for biostratigraphy, paleoecology or taxinomy are summarily described.  相似文献   

6.
Bruno David 《Geobios》1981,14(6):795-799
Three species of irregular see-urchins form the settlement of a marly level (lower Hauterivian) of the Castellane area. Two of them are strongly smaller than the norm. Their stunting is prouved by ontogenic, mecanical, sedimentological and ecological arguments. The ecological grounds of stunting are discussed.  相似文献   

7.
The study of the traditional Cottard layer forthe first time allows the exact succession of lower and middle Carixian ammonites to be established.The most striking fact is the evolution of the Tropidoceras-Acanthopleuroceras lineage, a regular modification of the ribbing density and L1 structure, an iterative variation of section and tuberculization.Precisions are given on Polymorphites and Beaniceras and three new species are described: Polymorphites evolutus, Beaniceras cottardiense, Acanthopleuroceras alisiense.  相似文献   

8.
Michel Brunet 《Geobios》1979,12(5):653-673
A screen washed and hand sorted sample of six tons sediments from La Milloque (Lot-et-Garonne) has yielded to the author several thousand micromammal's teeth. Among the Rodents, four extinct species of Cricetids have been recognized: Eucricetodon praecursor (Schaub, 1925); Adelomyarion viretiHugueney, 1969; Pseudocricetodon cf. thaleri (Hugueney, 1969); Melissiodon quercyiSchaub, 1920. The fossil remain's study affords many paleontological informations more particularly for E. praecursor, a previously poorly known species. About the upper Oligocene biochronology the four species' evolution degrees prove the statute of reference locality attributed to La Milloque, «mammalian timemark just below the reference locality of Coderet (Allier). Moreover it's pointed out that the locality of Rickenbach (Switzerland) is slightly older than La Milloque, whereas an intermediate age between La Milloque and Coderet can be suggested for the locality of Dicupentale (Tarn-et-Garonne).  相似文献   

9.
Evolutionary lineages of several limnic gastropod genera (Viviparus, Melanopsis, Theodoxus) from the Neogene of Kos island (Dodecanese, Greece) are described and interpreted. The attempt is made to analyse the paleoecological development of a limnic sedimentary basin in the eastern portion of Kos by means of Diatoms. Obviously, there is no relation between the chemical parameters of the water of the former lake and the morphological development of the gastropods. The lineages of Viviparus brevis, Theodoxus doricus and Melanopsis gorceixi are suggested to be caused by phyletic transformations and not by changing environmental conditions. It is, thus, possible to establish a local biostratigraphy based on subspecies, and moreover, a more regional one based on longer ranging species.  相似文献   

10.
The cytokinin activities of various 6-acylaminopurines, 6-alkylaminopurines, 6-acylamino-9-benzyl-purines as well as a series of isosteric-nitrogen derivatives of N6-(γ, γ-dimethylallyl)adenine (I6Ade) have been tested using the tobacco pith and the pea bud bioassays. The interactions between active, slightly active and inactive compounds have been studied with the last assay. Acylation decreases the biological activity; e.g., N6-benzoyl and N6-furoyladenines are less active than Na6-benzyladenine and kinetin. Substitution at the 9-position reduces (tobacco-pith assay) or suppresses (pea-bud assay) the phytohormonal activity of otherwise active 6-acylaminopurines. In isosteric derivatives, maximum activity occurs when the side chain has the same length as in 16Ade. After the analysis of interactions between more or less active compounds, it is suggested that the differences in cytokinin activity could be related to unequal affinities for a hypothetical receptor site.  相似文献   

11.
Tomato alcohol dehydrogenase has been purified 99-fold by affinity chromatography on Blue Sepharose CL-6B with 37% yield. The enzyme so obtained is homogenous in polyacrylamide gel electrophoresis. By adding 20% glycerol to the extraction and purification buffers, an enzyme is obtained which is stable for several months at 4°. The molecular weight values determined by gel filtration (Sephadex G 200) and polyacrylamide gradient gel electrophoresis on one hand and by polyacrylamide gel electrophoresis in sodium dodecyl sulfate on the other, show that the enzyme exists in dimeric form.  相似文献   

12.
13.
14.
Besides quercetin, kaempferol and isorhamnetin, at least three other flavonoids can be obtained from the leaves of Hymenosporum flavum after acid hydrolysis. One of these, a kaempferol derivative: p-hydroxyphenyl,(3,4′,5,7 -tetrahydroxy)-8-flavonyl, methylmethane or 8-α-methyl-C-(p-hydroxybenzyl)kaempferol has been identified by study of its spectral properties. It is probably an artifact formed during hydrochloric acid treatment of the leaves.  相似文献   

15.
Véra Eisenmann 《Geobios》1975,8(2):125-IN14
The fauna yielded by the Nihowan lower pleistocene lacustrine deposits includes two species of Equus beside one Hipparion. Equus sanmeniensis was described in 1930 by Teilhard de Chardin and Piveteau; this species is characterized by its large size and the presence of cups on all incisors. Equus teilhardi nov. sp. is smaller and its lower incisors are devoid of cups. It is the first time that such an absence is noted among eurasiatic Equus; till now only some californian, south-american and african species were known to have lowers incisors without cups. The finding of several Equids in the same deposits and the significance of the lack of cups are briefly discussed.  相似文献   

16.
Electrograms of the thoracic pulsatile organs and of the heart during emergence and expansion of the wings have been made. The mesotergal and metatergal organs function in a similar way: active periods are interrupted by short periods of rest, but the two organs contract with different but apparently independent rhythms. During emergence and expansion, the rate of contraction of the pulsatile organs increases twofold, and the resting periods disappear during the entire period of expansion of the wings. When the wings are removed or cut short, the activity of the pulsatile organs is inhibited.  相似文献   

17.
According to the classical stratigraphical conceptions, the Belgian Heersian was classified in the Landenian, and assigned to the basal Lower Eocene. It is composed of marine Sands of Orp-le-Grand, which contain a riche selacian fauna, also of Gelinden Marls covering and interpenetrating the Sands.Among the vertebrate remains recently discovered at Maret en Brabant in the marl facieswithin the Sands was a small tooth which represents the first mammalian remain from the Heersian, and attests the occurence of the insectivorous genus Adapisorex, hitherto known from the paleocene localities of Cernay-les-Reims and Walbeck. The specimen from Maret en Brabant reopens the question of the age of the Belgian Heersian and supports its classification within the Paleocene, according to paleobotanical data and indications obtained from the selacian fauna.  相似文献   

18.
Latex lutoids constitute a polydispersed vacuole with lysosomal character. Lutoids possess a membrane which retains ATP-ase and acid phosphatase activity. Acid phosphatase may be inhibited by ammonium molybdate or phosphate, making it possible to characterize an ATP-ase with an optimum pH of between 7·5 and 8·0. This ATP-ase is Mg2+ dependent, does not require K+ specifically but is affected by the ionic concentration of the medium.  相似文献   

19.
20.
A new succession of about fifteen coal seams has been discovered, in overturned position, between the “faille du Midi” and the classical Kilits Series in the Caydamar mines, Heraclee Basin, Turkey (gallery ?200/3400A). These beds, on the basis of plant spores, are Westpphalian A in age. The flora too is listed. Sixty-eight microspore and eighteen megaspore species were found. Comparison is made with spore assemblages from northern France.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号