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21.
High resolution palynological and geochemical data of sediment core GeoB 3910‐2 (located offshore Northeast Brazil) spanning the period between 19 600 and 14 500 calibrated year bp (19.6–14.5 ka) show a land‐cover change in the catchment area of local rivers in two steps related to changes in precipitation associated with Heinrich Event 1 (H1 stadial). At the end of the last glacial maximum, the landscape in semi‐arid Northeast Brazil was dominated by a very dry type of caatinga vegetation, mainly composed of grasslands with some herbs and shrubs. After 18 ka, considerably more humid conditions are suggested by changes in the vegetation and by Corg and C/N data indicative of fluvial erosion. The caatinga became wetter and along lakes and rivers, sedges and gallery forest expanded. The most humid period was recorded between 16.5 and 15 ka, when humid gallery (and floodplain) forest and even small patches of mountainous Atlantic rain forest occurred together with dry forest, the latter being considered as a rather lush type of caatinga vegetation. During this humid phase erosion decreased as less lithogenic material and more organic terrestrial material were deposited on the continental slope of northern Brazil. After 15 ka arid conditions returned. During the humid second phase of the H1 stadial, a rich variety of landscapes existed in Northeast Brazil and during the drier periods small pockets of forest could probably survive in favorable spots, which would have increased the resilience of the forest to climate change.  相似文献   
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Brown spider monkeys (Ateles hybridus) are one of the least known and more threatened primates in the Neotropics. Recognized as a species about a decade ago, field studies on these endangered primates have mainly focused on estimating local population densities. Since 2006, we habituated a group of wild brown spider monkeys at Serranía de Las Quinchas, Colombia, and studied their feeding ecology during 2.5 years using focal “subgroup” sampling, and conducted phenological surveys in order to estimate habitat‐wide fruit availability. Based on 847 hr of behavioral follows, brown spider monkeys spent approximately 25% of their time in feeding activities, and fed from fruits and leaves on at least 123 plant species. Ripe fruits were the most important item in the diet of A. hybridus at Las Quinchas comprising 92% of their feeding time. Probably due to the minor variation in the monthly proportion of fruits in brown spider monkey's diet throughout this study, there was no relation between habitat‐wide fruit availability and the proportion of fruit included in their monthly diet. The diet of brown spider monkeys at Las Quinchas is toward the high end of fruit intake, even within other wild spider monkeys’ populations, suggesting that these endangered primates might also be facing the challenges of being a large bodied fruit specialist under a regional scenario of habitat loss and fragmentation. Am. J. Primatol. 74:1097‐1105, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
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The spermatophore of the cave-spider Telema tenella is elaborated in the vas deferens. It has the shape of a long inverted gutter with two rows of digitations and spermatozoa piled up inside. The spermatozoon possesses a 9 + 3 axoneme, retracted in the cytoplasm to form from 4 to 4.5 peripheral whorls; the elongated nucleus and its acrosomal rod make 1.5 whorl. The spermatozoa keep the main part of their cytoplasm. The spermatophore is inserted in the male palp, then transferred to the female during coition. With the exception of this family, all other male Araneae transfer free spermatozoa during coition.  相似文献   
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Bulbophyllum nocturnum , a species of section Epicrianthes from New Britain, is described and illustrated. It is the first known example of an orchid species in which the flowers open after dark and close in the morning. The poorly understood pollination biology of section Epicrianthes, a clade with highly unusual flowers, is discussed. Attention is drawn to the close resemblance between the petal appendages of some species and the fruiting bodies of certain Myxogastria. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 344–350.  相似文献   
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Kuechler, R.R., Birgel, D, Kiel, S, Freiwald, A, Goedert, J.L., Thiel, V & Peckmann, J. 2011: Miocene methane‐derived carbonates from southwestern Washington, USA and a model for silicification at seeps. Lethaia, Vol. 45, pp. 259–273. Exotic limestone masses with silicified fossils, enclosed within deep‐water marine siliciclastic sediments of the Early to Middle Miocene Astoria Formation, are exposed along the north shore of the Columbia River in southwestern Washington, USA. Samples from four localities were studied to clarify the origin and diagenesis of these limestone deposits. The bioturbated and reworked limestones contain a faunal assemblage resembling that of modern and Cenozoic deep‐water methane‐seeps. Five phases make up the paragenetic sequence: (1) micrite and microspar; (2) fibrous, banded and botryoidal aragonite cement, partially replaced by silica or recrystallized to calcite; (3) yellow calcite; (4) quartz replacing carbonate phases and quartz cement; and (5) equant calcite spar and pseudospar. Layers of pyrite frequently separate different carbonate phases and generations, indicating periods of corrosion. Negative δ13Ccarbonate values as low as ?37.6‰ V‐PDB reveal an uptake of methane‐derived carbon. In other cases, δ13Ccarbonate values as high as 7.1‰ point to a residual, 13C‐enriched carbon pool affected by methanogenesis. Lipid biomarkers include 13C‐depleted, archaeal 2,6,10,15,19‐pentamethylicosane (PMI; δ13C: ?128‰), crocetane and phytane, as well as various iso‐ and anteiso‐carbon chains, most likely derived from sulphate‐reducing bacteria. The biomarker inventory proves that the majority of the carbonates formed as a consequence of sulphate‐dependent anaerobic oxidation of methane. Silicification of fossils and early diagenetic carbonate cements as well as the precipitation of quartz cement – also observed in other methane‐seep limestones enclosed in sediments with abundant diatoms or radiolarians – is a consequence of a preceding increase of alkalinity due to anaerobic oxidation of methane, inducing the dissolution of silica skeletons. Once anaerobic oxidation of methane has ceased, the pH drops again and silica phases can precipitate. □Biomarkers, carbonates, isotopes, methane, Miocene, silicification, Washington.  相似文献   
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A biogeographical analysis of crane flies (Diptera, Tipulomorpha) in the southern hemisphere is used to test if their distribution patterns provide evidence of biogeographical homology (shared history) in the South Pacific. Crane fly distributions are interpreted in light of patterns of endemism and diversity and published phylogenetic studies. A panbiogeographical approach, assuming that repeating distribution patterns strongly suggest the existence of past connections between the areas (biogeographical homology), is used. A clear pattern is revealed in which crane fly taxa shared between southern South America, New Zealand and Australia are restricted to that region. Thirty genera and subgenera, together comprising about 700 species, occur in both South America and Australasia and only in these areas. This distribution defines the limits of the South Pacific Track, a standard biogeographical pattern displayed by many taxa, including the southern beeches (Nothofagus). Although the distribution of some taxa spans the entire track, others are present in parts of the areas only, forming a nested set of distributions. Within the surveyed genera and subgenera, all individual species are endemic to one single region or continent, suggesting vicariance as the main process behind crane fly disjunctions in this part of the world. The nested set of distribution patterns could be explained by extinctions in areas where taxa were present previously. Alternatively, it may indicate historical absences and the existence of a heterogeneous set of ancestral distributional ranges. ‘Gondwanan’ may not be the best term for the observed disjunctions, which should be labelled as trans‐Pacific instead. Recent molecular estimates of divergence times suggest a Permian origin of the earliest extant Diptera lineages such as the Tipulomorpha, followed by fast radiation in the Triassic. Although the differentiation of some crane fly groups occurring in the region may have been driven by recent Mesozoic and Cenozoic events of continental breakup, as least part of the fauna may have evolved allopatrically in response to older events. This may explain the overlapping distribution of subgenera in large genera such as Gynoplistia.  相似文献   
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ABSTRACT Flipper banding has long been the primary method to identify individual penguins, despite studies indicating that it may be detrimental to breeding success and survival. Our objectives were to measure the effects that flipper bands may have on diving performance of little penguins to determine whether the bands may be detrimental. We studied short- and long-term direct effects of flipper banding on diving behavior of free-ranging little penguins (Eudyptula minor) by comparing diving behavior before and after banding and by comparing diving performance of unbanded birds to those that had carried flipper bands for several years, respectively. Recently banded birds displayed increases in multiple variables following banding. Long-term banded penguins did not exhibit differences to their unbanded counterparts in most variables examined. Our findings are useful to those considering or reviewing the use of bands in penguin study and management.  相似文献   
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