Le protée est-il équipé pour le magnétotactisme ?     

Hélène Bouquerel  Jean-Pierre Valet 《Comptes Rendus Geoscience》2005,337(9):806-813

It was suggested that the proteus blind cave salamander can sense the geomagnetic field using magnetic crystals (like magnetite). We attempted to check this hypothesis by measuring the magnetization and the magnetic mineralogy of proteus from the Moulis CNRS underground laboratory. The abdomen and the rear legs of the animals were the unique body parts that revealed a detectable saturation magnetization in the order of 10^?9 A?m². Because this magnetization was carried by magnetite crystals that have the same magnetic properties as the soil sampled in the cave, it is likely that they were ingested by the animals. Thus these experiments did not detect any crystal that would be responsible for magnetotactism. These results are in contrast with those published for the newt [J. Brassart, J.L. Kirschvink, J.B. Phillips, S.C. Borland, Ferromagnetic material in the eastern red-spotted newt, J. Exp. Biol. 202 (1999) 3155]. However the cryogenic magnetometers do not allow us to detect very small amounts of monodomain grains. This prevents us from any definite conclusion until the construction of a very sensitive cryogenic gradiometer. <em>To cite this article: H. Bouquerel, J.-P. Valet, C. R. Geoscience 337 (2005).em>  相似文献   

Saisonales Vorkommen von Arten der Saprolegniales und Leptomitales im Auesee und in der Fulda in Kassel (Hessen) unter Berücksichtigung fischpathogener Arten     

Alexandra Riethmüller  Ewald Langer 《洁净——土壤、空气、水》2005,33(6):622-634

Seasonal Occurrence of Species of Saprolegniales and Leptomitales in Lake Aue and the River Fulda in Kassel (Hesse) with Special Consideration of Fish Pathogenic Species In this study, we examined the occurrence of species of aquatic Oomycetes of Saprolegniales und Leptomitales in Lake Aue and the river Fulda in Kassel (Hesse, Germany) with special consideration of fish pathogenic species. We monthly collected water samples of both water bodies from July 2003 to June 2004. The baiting method was used to gain an insight into the specific seasonal occurrence of aquatic Oomycetes. Some species show a seasonal periodicity. Nine of 11 species of Saprolegniales isolated from the two water bodies, and Leptomitus lacteus (Roth) C. Agardh, one of the two species of Leptomitales, were already documented on fish according to references. Additionally, 7 of 10 species could according to references already be detected on fish species present in the two water bodies. Simultaneous measurements of limnological‐chemical parameters were done during the sampling of water for the isolation of aquatic Oomycetes. The results of some measurements, concerning the river Fulda, were additionally compared with the predetermined guideline values and limit values of water bodies of fish of the “Cyprinid region”.  相似文献   

Research on Radar Emitter Attribute Recognition Method     

GUAN Xin YI Xiao HE You 《地球空间信息科学学报》2006,9(1):45-48

Introduction Theprimarymissionofanelectronicwarfare dentificationsystemistodetectthepresenceof hostileemittersandidentifytheemittersas quicklyandaccuratelyaspossible[1,2].Thecur entrecognitionalgorithmsarebasicallymatc hingalgorithms.Theyperformasequenceo…  相似文献   

On age of Nazimovskaya and Khasan formations in the Paleogene succession of southwestern Primor’e     

B. I. Pavlyutkin  S. I. Nevolina  T. I. Petrenko  T. K. Kutub-Zade 《Stratigraphy and Geological Correlation》2006,14(4):444-457

Materials of previous studies and new original geological and paleobotanic data are used to substantiate synchronism (late Eocene) of the Khasan and Nazimovskaya formations, the key stratigraphic units of the Paleogene in Primor’e. Coal-bearing sediments of the units rest upon early-middle Eocene volcanics (Kraskino rhyolite tuffs, Zaisanovka basaltic andesites) being overlain by the lower Fatash Subformation of the lower Oligocene with flora of the Kraskino type. The Ust’-Davydovskaya Formation of the Rechnoi Peninsula (outskirts of Vladivostok) is the most probable analogue of the Khasan (=Nazimovskaya) Formation.  相似文献   

An Important Spreading Event of the Neo-Tethys Ocean during the Late Jurassic and Early Cretaceous: Evidence from Zircon U-Pb SHRIMP Dating on Diabase in Nagarze, Southern Tibet     

JIANG Sihong  NIE Fengjun  HU Peng  LIU Yan Institute of Mineral Resources  Chinese Academy of Geological Sciences  Beijing 《《地质学报》英文版》2006,80(4)

Widely distributed in Gyangze-Chigu area, southern Tibet, NW- and nearly E-W-trending diabase(gabbro)-gabbro diorite dykes are regarded as the product of the large-scale spreading of the late Neo-Tethys Ocean. In order to constrain the emplacement age of these dykes, zircons of two samples from diabases in Nagarze were dated by using the U-Pb SHRIMP method. Two nearly the same weighted mean 206Pb/238U ages were obtained in this paper, which are 134.9±1.8 Ma (MSWD= 0.65) and 135.5±2.1 Ma (MSWD=1.40), respectively. They not only represent the crystallization age of the diabase, but also documented an important spreading event of the Neo-Tethys Ocean during the late Jurassic and early Cretaceous. This dating result is of great significance to reconstruct the temporal framework of the late Neo-Tethys Ocean in the Qinghai-Tibet Plateau.  相似文献   

SEM–EDS analysis of western Mediterranean obsidians: a new tool for Neolithic provenance studies     

Franois-Xavier Le Bourdonnec  Grard Poupeau  Carlo Lugli 《Comptes Rendus Geoscience》2006,338(16):1150-1157

The contents of Na, Al, Si, K, Ca and Fe of 99 obsidians from the western Mediterranean islands of Lipari, Palmarola, Pantelleria and Sardinia were determined with the energy-dispersive spectrometer of a scanning electron microscope (SEM–EDS). The Na and in a lesser way other elements contents characterize any obsidian source-island. In Sardinia (80 samples), the four Monte Arci obsidian geochemical types can be discriminated from binary diagrams of element contents or by a discriminant analysis based on the six elements measured. It is concluded that SEM–EDS offers a new option for Neolithic obsidian provenance studies in this region. To cite this article: F.-X. Le Bourdonnec et al., C. R. Geoscience 338 (2006).  相似文献   

Les sondages électromagnétiques temporels comme outil de reconnaissance du gisement phosphaté de Sidi Chennane (Maroc) : apport à la résolution d'un problème d'exploitation     

Azzouz Kchikach  Pierre Andrieux  Mohammed Jaffal  Mostafa Amrhar  Mohammed Mchichi  Baadi Boya  Mbarek Amaghzaz  Thierry Veyrieras  Khadija Iqizou 《Comptes Rendus Geoscience》2006,338(5):289-296

Exploitation of the phosphatic layers in Sidi Chennane deposit (Morocco) collides frequently with problems bound to the existence, in the phosphatic series, of sterile bodies qualified as <em>derangementsem>. Our study shows that these bodies, masked by the Quaternary cover can be mapped using the Time-Domain ElectroMagnetic Soundings method (TDEM). It is based on the acquisition and the interpretation of a series of tests carried out above a visible <em>derangementem> in an old trench of exploitation and on 2500 TDEM soundings carried out in a virgin area of the deposit. The article concerns to the analysis of the results and of the proceeding for a possible large geophysics survey. <em>To cite this article: A. Kchikach et al., C. R. Geoscience 338 (2006).em>  相似文献   

Evaluation of stakeholder perspectives on the management of the stalked barnacles (Pollicipes pollicipes) resource in the Parque Natural do Sudoeste Alentejano e Costa Vicentina,Portugal     

《Marine Policy》2014

The stalked barnacle, <em>Pollicipes pollicipesem>, is a shellfish resource which has been traditionally harvested by the coastal communities of the Iberian Peninsula. However, in recent years <em>Pollicipesem> has attracted increased harvesting pressure due to its high market value. In a national park on the south-western coast of Portugal, legislation was formulated to address the overharvesting of this resource; however, its success has been limited due to lack of consensus among stakeholders. A Systems Approach Framework (SAF) was used to assess the socio-economic and cultural issues surrounding the harvest of <em>Pollicipesem>. As part of this, interviews and a questionnaire survey were undertaken in the municipality of Vila do Bispo, in order to explore the perspectives of the shell fishers, local residents and restaurateurs. The majority of the stakeholders believed that the resource was overharvested and that their needs should be considered as part of the legislation formulation process. The stakeholders also agreed that the local market should be re-established and that the temporal closure period should be reconsidered. Stakeholder opinions differed with regard to the level of coastal management enforcement required, the licence distribution process and the restrictions implemented by national park authorities. It is concluded that using information such as that gathered from local stakeholders, it should be possible to effectively extend the SAF to simulate scenarios for future management options.  相似文献   

山东东阿鱼山地质公园主要地质遗迹成因及评价     

吉龙江  赵红芬  刘文峰  韩亮  窦炳臣 《山东地质》2012,(3):12-14,18

地质公园是保护地质遗迹、维护生态环境、实现可持续发展战略的重要场所。通过对山东东阿鱼山省级地质公园的野外调查及研究分析,总结了鱼山地质公园内主要地质遗迹的形成原因并对其评价。认为：园内地质遗迹丰富、地学价值高、环境优美,能使人们更加直观的了解地壳的演变过程,又能够培养青少年对自然科学的爱好和兴趣。  相似文献   

Climatic Character of Marine Isotope Stage (MIS) 5e in the Representative Regions of the World: A Review     

Pei Qiaomin  Ma Yuzhen  Hu Caili  Li Dandan  Guo Chao  Liu Jierui 《地球科学进展》2016,31(11):1182-1196

The Last Interglacial or Marine Isotope Stage (MIS) 5e, is of great interest because it serves as an analog for the Holocene. The climate change and duration during Marine isotope stage (MIS) 5e are considerably well understood for recent and future climate. Despite great interest in this subject over many years, a number of issues concerning the climate circumstances of MIS 5e are by no means resolved. We analyzed 35 published palaeoclimate records with reliable chronologies and robust proxies in typical region of the world to evaluate climate change during MIS 5e. These data indicate that: ① The duration of this warm phase is thought to range from (128±2) ka to (116±2) ka. The climate of MIS 5e was likely relatively stable with a number of abrupt, weak amplitude, cool and/or arid events. And the difference between regions is noticeable for the occurrence, amplitude, onset and duration of these events. For example, marine records from the North Atlantic indicate that the climate of MIS 5e was relatively stable, however the records from Norwegian sea show that the climate of MIS 5e had a significant changes at the beginning and cold event in the Mid-Eemian; The &delta;¹⁸O, &delta;D and CH₄ in the ice cores from Greenland and Antarctica imply that climate was relatively stable during the last interglacial period, while in Europe from the north to the south the duration of this phase became shorter and the intensity of climatic events became stronger. In addition, the climatic conditions of MIS 5e reconstructed by climate proxy from China are various and have the subject of some controversy. ②The global climate response to the insolation forcing would have been uniform on suborbital timescale. Nevertheless, as a result of regional sundry climatic forcing factors, global millennial-scale/century-scale climate oscillations were marked by significant local features during stage 5e. ③ Based on the better chronological controls, the estimation of climate parameters, the high-resolution climate records, and precise knowledge of the phase relationship between climate changes in global, the earlier depiction for climate circumstances and environment change during Marine Isotope Stage 5e should be refined and our understanding of the climate dynamics and mechanism and climate modelling should be improved.  相似文献