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131.
John M. Huisman 《Phycological Research》2001,49(3):177-182
Echinophycus minutus gen. et sp. nov. (Ceramiales, Rhodophyta) is described for specimens collected from a deep‐water habitat in the Dampier Archipelago, northwestern Australia. Plants were dredged from a coarse sand/rubble habitat, where they were partially decumbent and attached to the substratum by numerous unicellular rhizoids, Thalli are to 25 mm in height, uniaxial, with four pericentral cells and a persistent pigmented trichoblast arising on each axial cell. Tricho‐blasts are arranged in a spiral pattern, with a 90° divergence between successive segments. Each trichoblast is composed of a basal cell bearing a cluster of unbranched filaments. Tetrasporangia are tetrahedral and formed in series in normal branches. Procarps have two sterile cell groups. Spermatangia are formed In heads that are terminal on trichoblasts. The new genus is placed in the tribe Brongniartelleae of the family Rhodomelaceae, differing from all other included genera in the morphology of the trichoblasts. 相似文献
132.
Linh M. Chau Cause Hanna Laurel T. Jenkins Rachel E. Kutner Elizabeth A. Burns Claire Kremen Michael A. D. Goodisman 《Ecology and evolution》2015,5(23):5573-5587
Invasive species cause extensive damage to their introduced ranges. Ocean archipelagos are particularly vulnerable to invasive taxa. In this study, we used polymorphic microsatellite markers to investigate the genetic structure of the social wasp Vespula pensylvanica in its native range of North America and its introduced range in the archipelago of Hawaii. Our goal was to gain a better understanding of the invasion dynamics of social species and the processes affecting biological invasions. We found that V. pensylvanica showed no significant genetic isolation by distance and little genetic structure over a span of 2000 km in its native range. This result suggests that V. pensylvanica can successfully disperse across large distances either through natural‐ or human‐mediated mechanisms. In contrast to the genetic patterns observed in the native range, we found substantial genetic structure in the invasive V. pensylvanica range in Hawaii. The strong patterns of genetic differentiation within and between the Hawaiian Islands may reflect the effects of geographic barriers and invasion history on gene flow. We also found some evidence for gene flow between the different islands of Hawaii which was likely mediated through human activity. Overall, this study provides insight on how geographic barriers, invasion history, and human activity can shape population genetic structure of invasive species. 相似文献
133.
Judith Denkinger Daniela Alarcon Bitinia Espinosa Lynn Fowler Cindy Manning Javier Oña Daniel M. Palacios 《Marine Mammal Science》2020,36(3):774-785
Killer whales (Orcinus orca) have strong social matrilineal bonds and form groups and long-lasting associations, but little is known about their population or social structure in an equatorial setting such as the waters around the Galápagos Islands. Using 91 encounters and identification photographs from 1991 to 2017, we identified 64 killer whales of which 18 individuals were locals with high resighting rates. Group size was small, ranging from 1 to 15 animals, with 69% of the groups containing four or fewer animals. Using social network analysis (SOCPROG 2.7) whales grouped into three distinct units and one loose association with frequent exchange between different groups. One male–male unit showed a strong association (association strength = 0.55). Overall, associations lasted over at least 3 years. Our data give first evidence of a loose social organization of Galápagos killer whales, similar to fission-fusion societies. 相似文献
134.
Simon G. Haberle 《Journal of Biogeography》2003,30(2):239-255
Aim To reconstruct the history of vegetation and environments using pollen, charcoal and sediment analysis, and to identify the timing and nature of climate change and human impact on the vegetation of a remote Pacific island. Location Cerro de Los Inocentes, 1000 m above sea level, Alexander Selkirk Island (33°45′S, 80°45′W), Chile. The westernmost island of the Juan Fernandez Archipelago, south‐east Pacific Ocean. Methods A 150‐cm long sediment core comprising 87 cm dark brown peat overlying 63 cm of yellow grey clay was extracted from a shallow depression on the southern slopes of Cerro de Los Inocentes. Pollen, charcoal, sediment and accelerator mass spectrometry radiocarbon analyses were used to construct a record of vegetation change through time. Numerical analysis of multispecies data allowed the classification of fossil assemblages into distinct pollen zones. Results Pollen and spores are preserved throughout the sediment with high concentrations coinciding with the beginning of organic sediment accumulation at around 8000 14C yr BP. Prior to 8000 14C yr BP, the deposition of clays, presumably from upslope erosion, occurred in a landscape sparsely vegetated by grasses, ferns and Pernettya rigida heath, including several plants that are only found 100–200 m above the site today (Zone CI‐1). After 8000 14C yr BP, a P. rigida heath was the dominant vegetation (Zone CI‐2). A shift to a wet heath–shrubland (Zone CI‐3) occurred at 6000 14C yr BP and was followed by a transition to a treefern–shrubland mosaic accompanied by periodic burning (Zone CI‐4) after 4500 14C yr BP. The impact of human occupation is evident in Zone CI‐5 at 450 14C yr BP with the loss of forest species, increased burning and invasion of the exotic plant Rumex. Main conclusions The pollen and charcoal record provides the first evidence of vegetation changes spanning at least the last 8000 14C yr BP from the high altitude environment of Alexander Selkirk Island. Prior to 8000 14C yr BP, the altitudinal ranges of different plant species may have been suppressed by a cooler and drier climate. Increasing precipitation and temperatures at the end of the last glacial period may have mobilized exposed sediments in a sparsely vegetated upland environment, altering local drainage patterns, eventually leading to slope stabilization and deposition of organic detritus under an increasing density of heath and shrub vegetation. The subalpine heath–shrubland persisted until 4500 14C yr BP when first evidence for sustained burning is found in association with the establishment of a more open treefern–shrubland vegetation pattern. In the absence of human occupation at this time, the influence of increased climatic variability associated with more frequent El Niño‐Southern Oscillation events during the mid to late Holocene is considered one of the main driving forces behind increased vegetation disturbance during this period. The record provides evidence that island vegetation patterns have been highly dynamic over millennial to decadal time‐scales and that the flora has persisted through periods of rapid and major climate change. This changed with the discovery of the island by European explorers in the late sixteenth century and the subsequent introduction of goats and exploitation and burning of forests, which resulted in the progressive destruction of native vegetation and the invasion of introduced plants. There is evidence that reduced burning and control of the goat population within the last 50 years has resulted in marginal recovery of some high altitude native plant species. 相似文献
135.
Previous research on barcoding sedges (Carex) suggested that basic searches within a global barcoding database would probably not resolve more than 60% of the world’s some 2000 species. In this study, we take an alternative approach and explore the performance of plant DNA barcoding in the Carex lineage from an explicitly regional perspective. We characterize the utility of a subset of the proposed protein-coding and noncoding plastid barcoding regions (matK, rpoB, rpoC1, rbcL, atpF-atpH, psbK-psbI) for distinguishing species of Carex and Kobresia in the Canadian Arctic Archipelago, a clearly defined eco-geographical region representing 1% of the Earth’s landmass. Our results show that matK resolves the greatest number of species of any single-locus (95%), and when combined in a two-locus barcode, it provides 100% species resolution in all but one combination (matK + atpFH) during unweighted pair-group method with arithmetic mean averages (UPGMA) analyses. Noncoding regions were equally or more variable than matK, but as single markers they resolve substantially fewer taxa than matK alone. When difficulties with sequencing and alignment due to microstructural variation in noncoding regions are also considered, our results support other studies in suggesting that protein-coding regions are more practical as barcoding markers. Plastid DNA barcodes are an effective identification tool for species of Carex and Kobresia in the Canadian Arctic Archipelago, a region where the number of co-existing closely related species is limited. We suggest that if a regional approach to plant DNA barcoding was applied on a global scale, it could provide a solution to the generally poor species resolution seen in previous barcoding studies. 相似文献
136.
Setoguchi H Yukawa T Tokuoka T Momohara A Sogo A Takaso T Peng CI 《Journal of plant research》2006,119(4):401-405
We investigated the phylogenetic relationships within the genus Cardiandra based on plastid DNA sequences. The phylogenetic tree showed that Cardiandra populations from the Ryukyu Islands (Japan) and Taiwan were monophyletic (Ryukyu–Taiwan clade), whereas taxa from China and mainland Japan were sisters to this clade. The divergence time between the Ryukyu–Taiwan clade and the other species was estimated to be 0.082 MYA, i.e., the late Pleistocene. The infrageneric and/or infraspecific differentiation of Cardiandra is estimated to have depended largely on allopatric differentiation caused by the presence or division of the past landbridge of the Ryukyu Islands, which connected mainland Japan to the Asian Continent during the Quaternary. 相似文献
137.
138.
Temporal dynamics and nestedness of an oceanic island bird fauna 总被引:1,自引:0,他引:1
Ermias T. Azeria Allan Carlson Tomas Pärt Christer G. Wiklund 《Global Ecology and Biogeography》2006,15(4):328-338
Aim To examine temporal variation in nestedness and whether nestedness patterns predict colonization, extinction and turnover across islands and species. Location Dahlak Archipelago, Red Sea. Method The distributions of land birds on 17 islands were recorded in two periods 30 years apart. Species and islands were reordered in the Nestedness Temperature Calculator, software for assessing degrees of nestedness in communities. The occupancy probability of each cell, i.e. species–island combinations, was calculated in the nested matrix and an extinction curve (boundary line) was specified. We tested whether historical and current nested ranks of species and islands were correlated, whether there was a relationship between occupancy probability (based on the historical data) and number of extinctions or colonizations (regression analyses) and whether the boundary line could predict extinctions and colonizations (chi‐square analyses). Results Historical and current nested ranks of islands and species were correlated but changes in occupancy patterns were common, particularly among bird species with intermediate incidence. Extinction and turnover of species were higher for small than large islands, and colonization was negatively related to isolation. As expected, colonizations were more frequent above than below the boundary line. Probability of extinction was highest at intermediate occupancy probability, giving a quadratic relationship between extinction and occupancy probability. Species turnover was related to the historical nested ranks of islands. Colonization was related negatively while extinction and occupancy turnover were related quadratically to historical nested ranks of species. Main conclusions Some patterns of the temporal dynamics agreed with expectations from nested patterns. However, the accuracy of the predictions may be confounded by regional dynamics and distributions of idiosyncratic, resource‐limited species. It is therefore necessary to combine nestedness analysis with adequate knowledge of the causal factors and ecology of targeted species to gain insight into the temporal dynamics of assemblages and for nestedness analyses to be helpful in conservation planning. 相似文献
139.
Ecological effects and distribution of invasive non-native mammals on the Canary Islands 总被引:4,自引:0,他引:4
- 1 The ecological effects and distribution of 13 invasive non‐native mammal species on the Canary Islands are reviewed.
- 2 Six species, representing six different taxonomic orders, are widely distributed and live on all seven main islands of the Canarian Archipelago: Felis catus, Capra hircus, Rattus rattus, Rattus norvegicus, Mus domesticus and Oryctolagus cuniculus. Atelerix algirus is found on four islands while six further species are present on only one island: Crocidura russula, Suncus etruscus, Rousettus egyptiacus, Ovis gmelini, Ammotragus lervia and Atlantoxerus getulus.
- 3 Five species have an omnivorous diet, four are herbivorous, two insectivorous, one frugivorous and one carnivorous. The ecological effects and damage caused by these species in the natural habitats of the Canaries are similar to those in other insular regions. To our knowledge, the effects of two species, A. lervia (herbivorous) and A. getulus (omnivorous), are as yet unreported for other insular environments.
- 4 Two of the most pernicious effects caused by invasive non‐native mammal species in the Canaries consist of predation by feral cats of the three giant lizard species present in the western islands, but especially Gallotia gomerana, which is now on the verge of extinction; and the damage that the four species of herbivores cause to the endemic flora of the archipelago.
140.
Rhizophora stylosa is an ecologically important mangrove tree species that is found in tropical and subtropical regions. We isolated five polymorphic microsatellite loci from R. stylosa using a dual‐suppression‐polymerase chain reaction technique. These loci provided microsatellite markers with polymorphism of four alleles in each locus for overall population. The mean expected heterozygosities ranged from 0.113 to 0.473. 相似文献