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1.
Mamay , Sergius H. (U. S. Geological Survey, Washington, D. C.) Litostroma, a new genus of problematical algae from the Pennsylvanian of Oklahoma. Amer. Jour. Bot. 46(4): 283–292. Illus. 1959.—Litostroma oklahomense, gen. et sp. nov. is described on the basis of fossil plant material found in a Pennsylvanian marine limestone from the vicinity of McAlester, Oklahoma. Litostroma is a simple plant consisting of a small, irregularly shaped thallus 1 cell thick. Some thalli have small perforations and filament-like marginal outgrowths. The reproductive organs are not known. A marine fauna is intimately associated with Litostroma, and includes epiphytic Foraminifera preserved in actual growth positions on surfaces of the plants. The evidence indicates a marine habitat for Litostroma and, accordingly, algal affinity. Without information bearing on its reproductive organs or pigmentation, however, Litostroma cannot with assurance be assigned to any known group of algae. It possibly represents a group of green, brown, or even red algae.  相似文献   
2.
High degree of population subdivision in a widespread amphibian   总被引:5,自引:0,他引:5  
In general, amphibians are known to exhibit a higher degree of population subdivision than any other major animal taxa, but large-scale population genetic surveys of widely distributed species are still scarce, especially in the Eurasian continent. Using microsatellite markers and mitochondrial DNA sequences, we investigated the large-scale population genetic structure of the common frog (Rana temporaria)--one of the most widespread amphibians of the Palearctic region. Analyses of cytochrome b sequences revealed evidence for two distinct lineages inhabiting western and eastern parts of Europe. The separation of these lineages c. 700,000 years ago may have been induced by the onset of the Middle Pleistocene continental glaciations. Analyses of the variability of microsatellite loci within each of the clades revealed evidence for evolution of a high degree of population subdivision (FST approximately 0.23) even in northern Fennoscandia, colonized less than 10,000 years ago. The high level of substructuring is puzzling in the face of an apparently high dispersal capacity, as evidenced by the rather rapid recolonization of northern Europe. This suggests that processes other than restricted dispersal capacity need to be explored as explanations for the high degree of population subdivision in amphibians. The colonization of northern Europe has been accompanied by loss of genetic variability as evidenced by decreasing levels of intrapopulational genetic variability in microsatellite loci from south to north across Europe.  相似文献   
3.
The highly fossiliferous Virgilian (Upper Pennsylvanian) shales of the Kinney Brick Company quarry near Albuquerque, New Mexico, contain a diversified flora dominated by walchian conifers and neuropterid pteridosperms. Its other components include a specimen of Telangiopsis sp. and abundant material of Sphenopteridium manzanitanum, n. sp., a highly variable foliar form. Both genera are characteristically restricted to the Upper Mississippian, with the exception of one basal Pennsylvanian occurrence. Their occurrence together in the Kinney sediments and their possession in common of distinctive surficial ornamentation suggest that they represent dissociated parts of Diplopteridium, a very rare European Lower Carboniferous taxon. Other associated plants show later Paleozoic or even Early Mesozoic characteristics, which, together with the Mississippian elements, distinguish the Kinney site as paleobotanically unique.  相似文献   
4.
5.
Around the world, there is growing desire and momentum for ecological restoration to happen faster, with better quality, and in more extensive areas. The question we ask is how can laws and governmental regulations best contribute to effective, successful, and broad‐scale restoration? In the state of São Paulo, Brazil, there is a legal instrument (SMA 08‐2008) whose aim is to increase the effectiveness of tropical forest restoration projects in particular. It establishes, among other things, requirements regarding the minimum number of native tree species to be reached within a given period of time in restoration projects and the precise proportion of functional groups or threatened species to be included when reforestation with native species is used as a restoration technique. There are, however, two differing perspectives among Brazilian restoration ecologists on the appropriateness of such detailed legal rules. For some, the rules help increase the chances that mandatory projects of ecological restoration will succeed. For the other group, there is no single way to achieve effective ecosystem restoration, and the existing science and know‐how are far from sufficient to establish standardized technical and methodological norms or to justify that such norms be imposed. Both points of view are discussed here, aiming to help those developing new legislation and improving existing laws about ecological restoration. The precedents established in São Paulo, and at the federal level in Brazil, and the ongoing debate about those laws are worth considering and possibly applying elsewhere.  相似文献   
6.
We investigated how deciduousness of overstory tree species influences the community structure and species composition in the understory. The results suggest that deciduous overstory trees have positive effects on light‐demanding species, and that the processes underlying such effects may involve reduced competition for light or facilitation through increased water availability.  相似文献   
7.
Ohne ZusammenfassungDas druckfertige russische Manuskript wurde in Kuschakewitschs Nachlaß gefunden und von mir wortgetreu ins Deutsche übertragen. Die Niederschrift datiert aus dem Jahre 1919.  相似文献   
8.
Charliea is a new genus (type-species: C. manzanitana), based on pinnately compound leaf material from the richly fossiliferous Virgilian (Upper Pennsylvanian) shales of the Kinney Brick Company quarry near Albuquerque, New Mexico. In several features Charliea resembles Russellites or a zamioid cycad. It has linear-oblong pinnae with broad, oblique attachment and a truncate tip, which is deeply incised to form two to four nearly equal lobes. The venation is simple, parallel, and sparingly dichotomous, each vein ending at the distal margin. The Kinney beds also contain Plagiozamites planchardi, another zamioid form with parallel-veined pinnae, differing from Charliea chiefly in having rounded tips and veins ending in the denticulate margins. An unnamed third form (genus B) in the Kinney beds has long, narrow pinnae with parallel veins and blunt tips; this strongly resembles the Mesozoic conifer Podozamites, but may just as well represent a cycadophyte. Another unnamed taxon (genus A), from an Upper Pennsylvanian deposit in Jack County, Texas, resembles genus B or Russellites in general shape and venation, but the critical distal margins are unknown. In their single-ordered parallel venation, these four foliar types contrast sharply with the two-ordered pinnate venation of most Pennsylvanian fern-like leaves, and seem to foreshadow Mesozoic morphologies. This tendency toward precocious evolution of parallel-veined foliar form in North America is also expressed by a single occurrence of the Asiatic, Permian genus Tingia in the Lower Pennsylvanian of Utah, and by the presence of the predominantly Triassic cycadeoid genus Pterophyllum in the Lower Permian of Texas.  相似文献   
9.
Archaeocalamites lazarii, sp. nov., is based on a few vegetative compressions from the mid-Lower Permian Leonard Series near Fulda, north-central Texas. It is a minor component of a rich biota that includes sphenophylls, pteridophylls, conifers, conchostracan crustaceans, eurypterids, arachnids, insects, xenocanth sharks, and coprolites attributed to tetrapods. Biota and sedimentology indicate deposition in a small freshwater body on a deltaic floodplain. Leaves of A. lazarii differ in size and posture from those of the widespread and characteristically Mississippian aggregate species A. radiatus; nonpreservation of rooting and reproductive organs prevents interpretation of its phylogenetic relationship with other equisetaleans. The main significance of A. lazarii is that it extends the recorded stratigraphic range of the Archaeocalamitaceae from the lowermost Pennsylvanian (Namurian B) to the mid-Lower Permian (Artinskian), leaving a hiatus in records of approximately 55 Ma. This Lazarus taxon also occurs with possibly the youngest recorded eurypterid.  相似文献   
10.
为检验阿尔泰林蛙(Rana altaica)的系统发育地位及其物种有效性,该文运用线粒体细胞色素b基因,应用贝叶斯分析和最大简约方法构建了欧哑人陆分布的部分林蛙的系统发育关系.两种分析方法均支持阿尔泰林蛙在田野林蛙(R.arvalis)这一分支的内部.单倍型网络图显示来自阿尔泰地区和中西伯利亚地区所谓的阿尔泰林蛙与田野林蛙有共享单倍型.通过该文母系遗传发育分析结果显爪阿尔泰林蛙种级地位不成立,是田野林蛙的同物异名.另外,该文实验分析结果提示,对中国分布的林蛙内部种组划分应建立在系统进化关系的基础上重新进行评估.  相似文献   
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