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C. N. Spottiswoode M. Wondafrash M. N. Gabremichael Y. Dellelegn Abebe M. A. K. Mwangi N. J. Collar & P. M. Dolman 《Animal Conservation》2009,12(3):249-257
Rangeland degradation by livestock threatens several restricted-range species, but is largely overlooked by conservation biologists. The Sidamo lark Heteromirafra sidamoensis , confined to the Liben Plain grassland in southern Ethiopia, is critically endangered by bush encroachment, permanent settlement and agricultural conversion. Its global range was previously estimated at 760 km2 , but in 2007–2008 available habitat covered<35 km2 . Density estimates from multi-model inference analysis of distance transect data provided a global population estimate of 90–256 adults (possibly with a serious sex-ratio bias towards males). Logistic regression models of habitat selection showed that males preferentially occurred in areas of grassland with greater cover of medium-length grass (5–15 cm), less cover of bare ground and fewer bushes. Habitat transects extending outward from its core range revealed massive and rapid bush encroachment, corroborating information from semi-structured interviews. The survival of both local Borana pastoralism and this species – mainland Africa's likeliest first avian extinction – depends on restoring seasonal patterns of grazing, resisting agricultural conversion of grasslands, reversing fire suppression policies and clearing bush. 相似文献
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Heidi Gytz Durita Mohr Paulina Seweryn Yuichi Yoshimura Zarina Kutlubaeva Fleur Dolman Bosene Chelchessa Alexander B. Chetverin Frans?A.?A. Mulder Ditlev E. Brodersen Charlotte R. Knudsen 《Nucleic acids research》2015,43(22):10893-10906
Upon infection of Escherichia coli by bacteriophage Qβ, the virus-encoded β-subunit recruits host translation elongation factors EF-Tu and EF-Ts and ribosomal protein S1 to form the Qβ replicase holoenzyme complex, which is responsible for amplifying the Qβ (+)-RNA genome. Here, we use X-ray crystallography, NMR spectroscopy, as well as sequence conservation, surface electrostatic potential and mutational analyses to decipher the roles of the β-subunit and the first two oligonucleotide-oligosaccharide-binding domains of S1 (OB1–2) in the recognition of Qβ (+)-RNA by the Qβ replicase complex. We show how three basic residues of the β subunit form a patch located adjacent to the OB2 domain, and use NMR spectroscopy to demonstrate for the first time that OB2 is able to interact with RNA. Neutralization of the basic residues by mutagenesis results in a loss of both the phage infectivity in vivo and the ability of Qβ replicase to amplify the genomic RNA in vitro. In contrast, replication of smaller replicable RNAs is not affected. Taken together, our data suggest that the β-subunit and protein S1 cooperatively bind the (+)-stranded Qβ genome during replication initiation and provide a foundation for understanding template discrimination during replication initiation. 相似文献
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Home‐range size and habitat use of European Nightjars Caprimulgus europaeus nesting in a complex plantation‐forest landscape 下载免费PDF全文
In Europe, the consequences of commercial plantation management for birds of conservation concern are poorly understood. The European Nightjar Caprimulgus europaeus is a species of conservation concern across Europe due to population depletion through habitat loss. Pine plantation‐forest is now a key Nightjar nesting habitat, particularly in northwestern Europe, and increased understanding of foraging habitat selection is required. We radiotracked 31 Nightjars in an extensive (185‐km2) complex conifer plantation landscape in 2009 and 2010. Home‐range 95% kernels for females, paired males and unpaired males were an order of magnitude larger than song territories of paired males, emphasizing the importance of habitats beyond the song territory. Nightjars travelled a mean maximum distance of 747 m from the territory centre each night. Home‐range placement relative to landscape composition was examined by compositional analysis. Pre‐closure canopy forest (aged 5–10 years) was selected at all scales (MCP, 95% and 50% kernels), with newly planted forest (aged 0–4 years) also selected within 50% kernels. For telemetry fixes relative to habitat composition within 2 km of their territory centre, individuals again selected pre‐closure and newly planted forest, and also grazed grass heath. Open ungrazed habitat was not selected, with implications for open habitat planning for biodiversity conservation within public‐owned forests. Despite the Nightjars’ selection for younger growth, moth biomass was greater in older forest stands, suggesting that foraging site selection reflects ease of prey capture rather than prey abundance. Within large plantation‐forest landscapes, a variety of growth stages is important for this species and our results suggest that grazing of open habitats within and adjacent to forest will additionally benefit the European Nightjar. 相似文献
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Chen A Cauchon E Chefson A Dolman S Ducharme Y Dubé D Falgueyret JP Fournier PA Gagné S Gallant M Grimm E Han Y Houle R Huang JQ Hughes G Jûteau H Lacombe P Lauzon S Lévesque JF Liu S Macdonald D Mackay B McKay D Percival MD St-Jacques R Toulmond S 《Bioorganic & medicinal chemistry letters》2011,21(13):3976-3981
The design and optimization of a novel series of renin inhibitor is described herein. Strategically, by committing the necessary resources to the development of synthetic sequences and scaffolds that were most amenable for late stage structural diversification, even as the focus of the SAR campaign moved from one end of the molecule to another, highly potent renin inhibitors could be rapidly identified and profiled. 相似文献
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Coral bleaching: one disturbance too many for near-shore reefs of the Great Barrier Reef 总被引:1,自引:0,他引:1
The dynamic nature of coral communities can make it difficult to judge whether a reef system is resilient to the current disturbance
regime. To address this question of resilience for near-shore coral communities of the Great Barrier Reef (Australia) a data
set consisting of 350 annual observations of benthic community change was compiled from existing monitoring data. These data
spanned the period 1985–2007 and were derived from coral reefs within 20 km of the coast. During years without major disturbance
events, cover increase of the Acroporidae was much faster than it was for other coral families; a median of 11% per annum
compared to medians of less than 4% for other coral families. Conversely, Acroporidae were more severely affected by cyclones
and bleaching events than most other families. A simulation model parameterised with these observations indicated that while
recovery rates of hard corals were sufficient to compensate for impacts associated with cyclones and crown-of-thorns starfish,
the advent of mass bleaching has lead to a significant change in the composition of the community and a rapid decline in hard
coral cover. Furthermore, if bleaching events continue to occur with the same frequency and severity as in the recent past,
the model predicts that the cover of Acroporidae will continue to decline. Although significant cover of live coral remains
on near-shore reefs, and recovery is observed during inter-disturbance periods, it appears that this system will not be resilient
to the recent disturbance regime over the long term. Conservation strategies for coral reefs should focus on both mitigating
local factors that act synergistically to increase the susceptibility of Acroporidae to climate change while promoting initiatives
that maximise the recovery potential from inevitable disturbances. 相似文献
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