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991.
Emily L. Bruns Ian Miller Michael E. Hood Valentina Carasso Janis Antonovics 《Evolution; international journal of organic evolution》2019,73(3):497-510
In flowering plants, the evolution of females is widely hypothesized to be the first step in the evolutionary pathway to separate male and female sexes, or dioecy. Natural enemies have the potential to drive this evolution if they preferentially attack hermaphrodites over females. We studied sex‐based differences in exposure to anther‐smut (Microbotryum), a sterilizing pollinator‐transmitted disease, in Dianthus pavonius, a gynodioecious perennial herb. We found that within a heavily diseased population, females consistently had lower levels of Microbotryum spore deposition relative to hermaphrodites and that this difference was driven by rapid floral closing in females following successful pollination. We further show that this protective closing behavior is frequency dependent; females close faster when they are rare. These results indicate that anther‐smut disease is an important source of selection for females, especially since we found in a common garden experiment no evidence that females have any inherent fecundity advantages over hermaphrodites. Finally, we show that among populations, those where anther‐smut is present have a significantly higher frequency of females than those where the disease is absent. Taken together our results indicate that anther‐smut disease is likely an important biotic factor driving the evolution and maintenance of females in this gynodioecious species. 相似文献
992.
Adam Heikal Yoshio Nakatani Wanting Jiao Chris Wilson David Rennison Marion R. Weimar Emily J. Parker Margaret A. Brimble Gregory M. Cook 《Bioorganic & medicinal chemistry letters》2018,28(13):2239-2243
Energy generation is a promising area of drug discovery for both bacterial pathogens and parasites. Type II NADH dehydrogenase (NDH-2), a vital respiratory membrane protein, has attracted attention as a target for the development of new antitubercular and antimalarial agents. To date, however, no potent, specific inhibitors have been identified. Here, we performed a site-directed screening technique, tethering-fragment based drug discovery, against wild-type and mutant forms of NDH-2 containing engineered active-site cysteines. Inhibitory fragments displayed IC50 values between 3 and 110?μM against NDH-2 mutants. Possible binding poses were investigated by in silico modelling, providing a basis for optimisation of fragment binding and improved potency against NDH-2. 相似文献
993.
994.
Christine L. Goodale Steven A. Thomas Guinevere Fredriksen Emily M. Elliott Kathryn M. Flinn Thomas J. Butler M. Todd Walter 《Biogeochemistry》2009,93(3):197-218
Atmospheric deposition contributes a large fraction of the annual nitrogen (N) input to the basin of the Susquehanna River,
a river that provides two-thirds of the annual N load to the Chesapeake Bay. Yet, there are few measurements of the retention
of atmospheric N in the Upper Susquehanna’s forested headwaters. We characterized the amount, form (nitrate, ammonium, and
dissolved organic nitrogen), isotopic composition (δ15N- and δ18O-nitrate), and seasonality of stream N over 2 years for 7–13 catchments. We expected high rates of N retention and seasonal
nitrate patterns typical of other seasonally snow-covered catchments: dormant season maxima and growing season minima. Coarse
estimates of N export indicated high rates of inorganic N retention (>95%), yet streams had unexpected seasonal nitrate patterns,
with summer peaks (14–96 μmol L−1), October crashes (<1 μmol L−1), and modest rebounds during the dormant season (<1–20 μmol L−1). Stream δ18O-nitrate values indicated microbial nitrification as the primary source of stream nitrate, although snowmelt or other atmospheric
source contributed up to 47% of stream nitrate in some March samples. The autumn nitrate crash coincided with leaffall, likely
due to in-stream heterotrophic uptake of N. Hypothesized sources of the summer nitrate peaks include: delayed release of nitrate
previously flushed to groundwater, weathering of geologic N, and summer increases in net nitrate production. Measurements
of shale δ15N and soil-, well-, and streamwater nitrate within one catchment point toward a summer increase in soil net nitrification
as the driver of this pattern. Rather than seasonal plant demand, processes governing the seasonal production, retention,
and transport of nitrate in soils may drive nitrate seasonality in this and many other systems. 相似文献
995.
Effects of thyroxine exposure on the Twist 1 +/− phenotype: A test of gene–environment interaction modeling for craniosynostosis 下载免费PDF全文
996.
Rui Faria Pragya Chaube Hernn E. Morales Tomas Larsson Alan R. Lemmon Emily M. Lemmon Marina Rafajlovi Marina Panova Mark Ravinet Kerstin Johannesson Anja M. Westram Roger K. Butlin 《Molecular ecology》2019,28(6):1375-1393
Both classical and recent studies suggest that chromosomal inversion polymorphisms are important in adaptation and speciation. However, biases in discovery and reporting of inversions make it difficult to assess their prevalence and biological importance. Here, we use an approach based on linkage disequilibrium among markers genotyped for samples collected across a transect between contrasting habitats to detect chromosomal rearrangements de novo. We report 17 polymorphic rearrangements in a single locality for the coastal marine snail, Littorina saxatilis. Patterns of diversity in the field and of recombination in controlled crosses provide strong evidence that at least the majority of these rearrangements are inversions. Most show clinal changes in frequency between habitats, suggestive of divergent selection, but only one appears to be fixed for different arrangements in the two habitats. Consistent with widespread evidence for balancing selection on inversion polymorphisms, we argue that a combination of heterosis and divergent selection can explain the observed patterns and should be considered in other systems spanning environmental gradients. 相似文献
997.
Ocean acidification lowers the saturation state of calcium carbonate, decreasing net calcification and compromising the skeletons of organisms such as corals, molluscs and algae. These calcified structures can protect organisms from predation and improve access to light, nutrients and dispersive currents. While some species (such as urchins, corals and mussels) survive with decreased calcification, they can suffer from inferior mechanical performance. Here, we used cantilever beam theory to test the hypothesis that decreased calcification would impair the mechanical performance of the green alga Acetabularia acetabulum along a CO2 gradient created by volcanic seeps off Vulcano, Italy. Calcification and mechanical properties declined as calcium carbonate saturation fell; algae at 2283 µatm CO2 were 32% less calcified, 40% less stiff and 40% droopier. Moreover, calcification was not a linear proxy for mechanical performance; stem stiffness decreased exponentially with reduced calcification. Although calcifying organisms can tolerate high CO2 conditions, even subtle changes in calcification can cause dramatic changes in skeletal performance, which may in turn affect key biotic and abiotic interactions. 相似文献
998.
Emily E. Puckett Thea V. Kristensen Clay M. Wilton Sara B. Lyda Karen V. Noyce Paula M. Holahan David M. Leslie Jr Jeff Beringer Jerrold L. Belant Don White Jr Lori S. Eggert 《Molecular ecology》2014,23(10):2414-2427
Bottlenecks, founder events, and genetic drift often result in decreased genetic diversity and increased population differentiation. These events may follow abundance declines due to natural or anthropogenic perturbations, where translocations may be an effective conservation strategy to increase population size. American black bears (Ursus americanus) were nearly extirpated from the Central Interior Highlands, USA by 1920. In an effort to restore bears, 254 individuals were translocated from Minnesota, USA, and Manitoba, Canada, into the Ouachita and Ozark Mountains from 1958 to 1968. Using 15 microsatellites and mitochondrial haplotypes, we observed contemporary genetic diversity and differentiation between the source and supplemented populations. We inferred four genetic clusters: Source, Ouachitas, Ozarks, and a cluster in Missouri where no individuals were translocated. Coalescent models using approximate Bayesian computation identified an admixture model as having the highest posterior probability (0.942) over models where the translocation was unsuccessful or acted as a founder event. Nuclear genetic diversity was highest in the source (AR = 9.11) and significantly lower in the translocated populations (AR = 7.07–7.34; P = 0.004). The Missouri cluster had the lowest genetic diversity (AR = 5.48) and served as a natural experiment showing the utility of translocations to increase genetic diversity following demographic bottlenecks. Differentiation was greater between the two admixed populations than either compared to the source, suggesting that genetic drift acted strongly over the eight generations since the translocation. The Ouachitas and Missouri were previously hypothesized to be remnant lineages. We observed a pretranslocation remnant signature in Missouri but not in the Ouachitas. 相似文献
999.
Günther Klonner Johannes Wessely Andreas Gattringer Dietmar Moser Iwona Dullinger Karl Hülber Sabine B. Rumpf Svenja Block Oliver Bossdorf Marta Carboni Luisa Conti Wayne Dawson Emily Haeuser Martin Hermy Tamara Münkemüller Madalin Parepa Wilfried Thuiller Sebastiaan Van der Veken Kris Verheyen Mark van Kleunen Franz Essl Stefan Dullinger 《Ecography》2019,42(9):1548-1557
Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level. 相似文献
1000.
Functional consequences of cysteine modification in the ligand binding sites of peroxisome proliferator activated receptors by GW9662 总被引:21,自引:0,他引:21