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Joseph D. Manthey Carl H. Oliveros Michael J. Andersen Christopher E. Filardi Robert G. Moyle 《Evolution; international journal of organic evolution》2020,74(8):1788-1803
As a dispersive lineage expands its distribution across a heterogeneous landscape, it leaves behind allopatric populations with varying degrees of geographic isolation that often differentiate rapidly. In the case of oceanic islands, even narrowly separated populations often differentiate, which seems contrary to the highly dispersive nature of the founding lineage. This pattern of highly dispersive lineages differentiating across narrow sea barriers has perplexed biologists for more than a century. We used two reduced-representation genomic datasets to examine the diversification of a recent, rapid geographic radiation, the white-eyes (Aves: Zosterops) of the Solomon Islands. We incorporated methods that targeted phylogenetic structure, population structure, and explicit tests for gene flow. Both datasets showed evidence of gene flow among species, but not involving the closely spaced islands in the New Georgia Group. Instead, gene flow has occurred among the larger islands in the archipelago, including those recently connected by land bridges as well as those isolated by large expanses of deep ocean. Populations separated by shallow seas, and connected by land bridges during glacial cycles, ranged from no differentiation to both phenotypic and genomic differentiation. These complex patterns of gene flow and divergence support a model of rapid geographic radiation in which lineages differentially evolve dispersal disparity and phenotypic differences. 相似文献
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This study was designed to investigate spatial and temporal variation in Gelidium canariensis populations at two shores in
northern Gran Canaria during two years. Spatial scales ranged from some hundred meters (distance between shores), 10 to 30
m (distance between plots) to less than 3 m (distance between quadrats). Gelidium individuals were defined as distinct Gelidium
clumps. The results show a significant difference in size of clumps between shores, but not on the smaller spatial scales.
No significant temporal variation was found. There was no significant temporal or spatial variation in standing crop or density
(counts made in quadrats where Gelidium was present, rather than counts for the total shore). Sporophytic and gametophytic
clumps were also distinguished by identifying reproductive structures in the field. The total proportion of sporophytes was
larger than the proportion of gametophytes, but at a smaller scale there could be a shift in dominance. The survival rate
of clumps was similar between shores with a mean survival rate of 85%, but there was a significant difference in recruitment
between shores. The results indicate a stable population structure.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Marcia Ricci 《Biodiversity and Conservation》2006,15(10):3111-3130
Was realized field studies and ex situ propagation on the vascular flora of Juan Fernández Archipelago during 15 year period.
To evaluate the conservation status of a total of 133 species and subspecies of vascular endemic plants I used a IUCN classification
founding: 2 species extinct, 1 extinct in it natural habitat, 52 critically endangered, 37 endangered and 9 vulnerable. Thus,
73.8% are contained in a threat category; only 24 taxon can be considered to be of a lesser conservation concern. The largest
threat of extinction is a reduction in individuals in local populations resulting in small, isolated populations. This habitat
fragmentation and a reduction in endemic flora has also impacted endemic fauna. Besides, during this period was propagated
in nurseries a total of 80 of these species and subspecies (60%). It seem clear the necessity to continue to actions conserve
this particular ecosystem. 相似文献
7.
SHAUN A. FORGIE SARA L. GOODACRE MARTIN I. TAYLOR BRENT C. EMERSON 《Molecular ecology resources》2006,6(3):820-822
The Canary Island pine weevil Brachyderes rugatus (Wollaston) consists of four allopatric subspecies that are thought to have arisen from several historic colonization events within the archipelago. We have isolated and optimized seven microsatellite loci from Brachyderes rugatus calvus from Gran Canaria. Six of these loci are polymorphic within B. rugatus (11–22 alleles per locus; heterozygosity between 0.43 and 0.84). There is no evidence for heterozygote deficit within populations or for linkage disequilibrium between pairs of loci. These molecular markers are likely to prove useful tools for quantifying the genetic variability of bottlenecked island populations. 相似文献
8.
Contrasting population changes in sympatric penguin species in association with climate warming 总被引:2,自引:0,他引:2
JAUME FORCADA P. N. TRATHAN K. REID E. J. MURPHY J. P. CROXALL 《Global Change Biology》2006,12(3):411-423
Climate warming and associated sea ice reductions in Antarctica have modified habitat conditions for some species. These include the congeneric Adélie, chinstrap and gentoo penguins, which now demonstrate remarkable population responses to regional warming. However, inconsistencies in the direction of population changes between species at different study sites complicate the understanding of causal processes. Here, we show that at the South Orkney Islands where the three species breed sympatrically, the less ice‐adapted gentoo penguins increased significantly in numbers over the last 26 years, whereas chinstrap and Adélie penguins both declined. These trends occurred in parallel with regional long‐term warming and significant reduction in sea ice extent. Periodical warm events, with teleconnections to the tropical Pacific, caused cycles in sea ice leading to reduced prey biomass, and simultaneous interannual population decreases in the three penguin species. With the loss of sea ice, Adélie penguins were less buffered against the environment, their numbers fluctuated greatly and their population response was strong and linear. Chinstrap penguins, considered to be better adapted to ice‐free conditions, were affected by discrete events of locally increased ice cover, but showed less variable, nonlinear responses to sea ice loss. Gentoo penguins were temporarily affected by negative anomalies in regional sea ice, but persistent sea ice reductions were likely to increase their available niche, which is likely to be substantially segregated from that of their more abundant congeners. Thus, the regional consequences of global climate perturbations on the sea ice phenology affect the marine ecosystem, with repercussions for penguin food supply and competition for resources. Ultimately, variability in penguin populations with warming reflects the local balance between penguin adaptation to ice conditions and trophic‐mediated changes cascading from global climate forcing. 相似文献
9.
Distribution of alien plant species in relation to human disturbance on the Georgia Sea Islands 总被引:3,自引:0,他引:3
Abstract. This study investigates the effects of human disturbance and environmental factors on the distribution of alien plant species on the Georgia Sea Islands (GSI), USA. We sampled the absolute cover of native and alien plant species on two tourist islands (St. Simons Island and Jekyll Island) and on two protected National Wildlife Refuge Islands (Blackbeard Island and Wassaw Island). On each island, vegetation composition and environmental variables (soil properties and salt spray) were measured in two habitats that differed substantially in their degree of environmental stress, the more exposed primary dune and the more sheltered and inland maritime forest. Sites were further stratified within each habitat into areas that had different levels of human disturbance. Many alien species were present on all islands and the absolute cover of alien species was not significantly different among islands even though they varied substantially in their degree of accessibility and overall land use. Alien plant cover was appreciably greater in severely disturbed sites than in less disturbed sites on all islands and within both habitats. However, the difference between disturbance categories was much less pronounced in the primary dunes where human disturbance agents do not mitigate the harsh environmental conditions of this habitat (salt spray and saline soils). Alien plant abundance on the GSI is evidently more dependent upon the availability of disturbed ground than the degree of accessibility or overall island development. It appears that human disturbance increases alien cover in general, but in environments where the stress levels are not mitigated, human disturbance does little to foster alien invasions. 相似文献
10.
P. JONES S. SCHUBEL J. JOLLY M. de L. BROOKE J. VICKERY 《Biological journal of the Linnean Society. Linnean Society of London》1995,56(1-2):167-183
The little known endemic Henderson Island rail (or Henderson rail) Porzflna atra , inhabits forest on the coastal plain and upraised plateau of Henderson Island. Rails were studied for 15 months from January 1991 to March 1992. The population was estimated at c. 6200 individuals living in pairs or cooperative groups of 3–4 adults on territories averaging about 1 ha. Two or three eggs were laid in covered or open nests near the ground from mid-July to mid-February. Up to five consecutive nesting attempts were made in cases where eggs or young chicks were lost. Adults laid a second clutch when chicks were fully feathered at about one month of age. Both sexes incubated and helped rear the young. Older chicks sometimes helped feed younger siblings. Dispersal of juveniles from the natal territory took place in April. Adult birds underwent a rapid, simultaneous post-nuptial moult of the remiges in February-April; the post-juvenile moult involved body feathers only. Data on morphometries, breeding ecology, courtship behaviour and voice are compared with available information for the spotless crake P. tabuensis , the Henderson rail's closest relative and probable ancestor. These comparisons provide some information on how these two taxa have differentiated since rails arrived on Henderson Island some time in the last 380000 years. 相似文献