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101.
Sex allocation conflict between queens and workers in Formica pratensis wood ants predicts seasonal sex ratio variation
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Heikki Helanterä Pekka Pamilo 《Evolution; international journal of organic evolution》2016,70(10):2387-2394
Sex allocation theory predicts parents should adjust their investment in male and female offspring in a way that increases parental fitness. This has been shown in several species and selective contexts. Yet, seasonal sex ratio variation within species and its underlying causes are poorly understood. Here, we study sex allocation variation in the wood ant Formica pratensis. This species displays conflict over colony sex ratio as workers and queens prefer different investment in male and female offspring, owing to haplodiploidy and relatedness asymmetries. It is unique among Formica ants because it produces two separate sexual offspring cohorts per season. We predict sex ratios to be closer to queen optimum in the early cohort but more female‐biased and closer to worker optimum in the later one. This is because the power of workers to manipulate colony sex ratio varies seasonally with the availability of diploid eggs. Consistently, more female‐biased sex ratios in the later offspring cohort over a three‐year sampling period from 93 colonies clearly support our prediction. The resulting seasonal alternation of sex ratios between queen and worker optima is a novel demonstration how understanding constraints of sex ratio adjustment increases our ability to predict sex ratio variation. 相似文献
102.
Isolation and Characterization of a Hantavirus from Lemmus sibiricus: Evidence for Host Switch during Hantavirus Evolution 总被引:9,自引:0,他引:9
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Olli Vapalahti ke Lundkvist Vadim Fedorov Christopher J. Conroy Sirpa Hirvonen Angelina Plyusnina Kirill Nemirov Karl Fredga Joseph A. Cook Jukka Niemimaa Asko Kaikusalo Heikki Henttonen Antti Vaheri Alexander Plyusnin 《Journal of virology》1999,73(7):5586-5592
A novel hantavirus, first detected in Siberian lemmings (Lemmus sibiricus) collected near the Topografov River in the Taymyr Peninsula, Siberia (A. Plyusnin et al., Lancet 347:1835-1836, 1996), was isolated in Vero E6 cells and in laboratory-bred Norwegian lemmings (Lemmus lemmus). The virus, named Topografov virus (TOP), was most closely related to Khabarovsk virus (KBR) and Puumala viruses (PUU). In a cross focus reduction neutralization test, anti-TOP Lemmus antisera showed titers at least fourfold higher with TOP than with other hantaviruses; however, a rabbit anti-KBR antiserum neutralized TOP and KBR at the same titer. The TOP M segment showed 77% nucleotide and 88% amino acid identity with KBR and 76% nucleotide and 82% amino acid identity with PUU. However, the homology between TOP and the KBR S segment was disproportionately higher: 88% at the nucleotide level and 96% at the amino acid level. The 3' noncoding regions of KBR and the TOP S and M segments were alignable except for 113- and 58-nucleotide deletions in KBR. The phylogenetic relationships of TOP, KBR, and PUU and their respective rodent carriers suggest that an exceptional host switch took place during the evolution of these viruses; while TOP and KBR are monophyletic, the respective rodent host species are only distantly related. 相似文献
103.
Maternal effects in vulnerability to eye‐parasites and correlations between behavior and parasitism in juvenile Arctic charr
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Raine Kortet Tiina Lautala Jukka Kekäläinen Jouni Taskinen Heikki Hirvonen 《Ecology and evolution》2017,7(21):8780-8787
Hatchery‐reared fish show high mortalities after release to the wild environment. Explanations for this include potentially predetermined genetics, behavioral, and physiological acclimation to fish farm environments, and increased vulnerability to predation and parasitism in the wild. We studied vulnerability to Diplostomum spp. parasites (load of eye flukes in the lenses), immune defense (relative spleen size) and antipredator behaviors (approaches toward predator odor, freezing, and swimming activity) in hatchery‐reared juvenile Arctic charr (Salvelinus alpinus) using a nested mating design. Fish were exposed to eye‐fluke larvae via the incoming water at the hatchery. Fish size was positively associated with parasite load, but we did not find any relationship between relative spleen size and parasitism. The offspring of different females showed significant variation in their parasite load within sires, implying a dam effect in the vulnerability to parasites. However, the family background did not have any effect on spleen size. In the mean sire level over dams, the fish from the bolder (actively swimming) families in the predator trials suffered higher loads of eye flukes than those from more cautiously behaving families. Thus, the results indicate potentially maternally inherited differences in vulnerability to eye‐fluke parasites, and that the vulnerability to parasites and behavioral activity are positively associated with each other at the sire level. This could lead to artificial and unintentional selection for increased vulnerability to both parasitism and predation if these traits are favored in fish farm environments. 相似文献
104.
Strandberg U Käkelä A Lydersen C Kovacs KM Grahl-Nielsen O Hyvärinen H Käkelä R 《Physiological and biochemical zoology : PBZ》2008,81(4):473-485
Abstract This study of vertical fatty acid profiles, based on analysis of 58 fatty acids sampled at 3-mm intervals throughout the blubber column of a model marine mammal, the ringed seal (Pusa hispida), revealed three chemically distinct layers. The average depths of the outer and inner layers were quite consistent (approximately 1.5 and approximately 1 cm, respectively). Consequently, the middle layer varied greatly in thickness, from being virtually absent in the thinnest animals to 2.5 cm thick in the fattest. The relative consistencies of the thickness and composition of the layers as well as the nature of the fatty acids making up each layer support the generally assumed function of the various layers: (1) the outer layer is primarily structural and thermoregulatory, (2) the inner layer is metabolically active with a fatty acid composition that is strongly affected by recent/ongoing lipid mobilization/deposition, and (3) the middle layer is a storage site that contracts and expands with food availability/consumption. The remarkable dynamics of the middle layer along with the discrete pattern of stratification found in the vertical fatty acid profiles have important implications for methodological sampling design for studies of foraging ecology and toxicology based on analyses of blubber of marine mammals. 相似文献
105.
We conducted an 8-year exclosure experiment (1999–2006) in a forest–tundra ecotonal area in northwestern Finnish Lapland to
study the effects of reindeer grazing on vegetation in habitats of variable productivity and microhabitat structure. The experimental
sites included tundra heath, frost heath and riparian habitats, and the two latter habitats were characterized by hummock-hollow
ground forms. The total cover of vegetation, cover of willow (Salix spp.), dwarf birch (Betula nana), dwarf shrubs, forbs and grasses (Poaceae spp.) increased in exclosures in all habitats. The increase in the total cover of vegetation and in the covers of willow
and dwarf birch tended to be greatest in the least productive tundra heath. Opposing to the increase in the dominant vascular
plant groups, the cover and species number of bryophytes decreased in exclosures. We conclude that the effects of reindeer
grazing on vegetation composition depend on environmental heterogeneity and the responses vary among plant groups.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
106.
The impact of water-level regulation on littoral macroinvertebrate assemblages in boreal lakes 总被引:2,自引:1,他引:1
Regulation of lake water level for power production and flood control is among the major anthropogenic disturbances in boreal aquatic ecosystems. In Finland, over 300 lakes, representing one third of the total inland water area of the country, are artificially regulated. To study the effects of regulation on lake littoral macroinvertebrate communities, samples were taken from upper stony littoral and from lower soft bottom littoral habitats of 11 lakes with different regulation amplitudes (wintertime fall in water level 1.19–6.75 m). Twelve unregulated (wintertime fall in water level 0.11–0.55 m) lakes with otherwise similar characteristics were used as a reference. Non-metric Multidimensional Scaling ordinations showed that the composition of macroinvertebrate assemblages was strongly associated with the amplitude of water level regulation. Taxon richness also decreased with increasing intensity of regulation. Freezing and flushing of sediments in late winter are probably the most important factors leading to the impoverished littoral macroinvertebrate fauna. Invertebrates with long life cycle seem to be particularly vulnerable to unnatural water level fluctuation. Our results show that regulation of water level has a major impact on functionally significant lake littoral macroinvertebrates. 相似文献
107.
Jaana Kekkonen Heikki Kolunen Hannu Pieti?inen Patrik Karell Jon E. Brommer 《Journal of Ornithology》2008,149(1):59-66
Tawny owl reproduction and offspring sex ratios have been considered to depend on the abundance of small voles. We studied
reproductive performance (laying date, clutch and brood size) during 1995–2003 and offspring sex ratios from 1999 to 2003
in relation to the abundance of small voles and food delivered to the nest in a tawny owl population in southern Finland.
Abundance of small voles (field and bank voles) was based on trappings in the field, and estimates of food delivery was based
on diet analysis of food remains in the nest boxes. In this population, reproductive output was not related to the abundance
of small voles. Analysis of food delivered to the nest showed that the prey weight per offspring varied more than twofold
between years and revealed that this difference was mainly related to the proportion of water voles in the diet. Only the
number of water voles correlated with laying dates. Offspring sex ratios were weakly male biased (55%) but did not differ
from parity. Sex ratios were not related to the abundance of small voles, and we found no evidence that parents delivered
more food to nests with proportionally more offspring of the larger (female) sex. Our results underline the notion that populations
may differ in their sex allocation pattern, and suggest such differences may be due to diet. 相似文献
108.
109.
Myoung Soo Kwon Teija Kujala Minna Huotilainen Anna Shestakova Risto Näätänen Heikki Hämäläinen 《Bioelectromagnetics》2009,30(3):241-248
Previous studies on the effects of the mobile phone electromagnetic field (EMF) on various event‐related potential (ERP) components have yielded inconsistent and even contradictory results, and often failed in replication. The mismatch negativity (MMN) is an auditory ERP component elicited by infrequent (deviant) stimuli differing in some physical features from the repetitive frequent (standard) stimuli in a sound sequence. The MMN provides a sensitive measure for cortical auditory stimulus feature discrimination, regardless of attention and other contaminating factors. In this study, MMN responses to duration, intensity, frequency, and gap changes were recorded in healthy young adults (n = 17), using a multifeature paradigm including several types of auditory change in the same stimulus sequence, while a GSM mobile phone was placed on either ear with the EMF (902 MHz pulsed at 217 Hz; SAR1g = 1.14 W/kg, SAR10g = 0.82 W/kg, peak value = 1.21 W/kg, measured with an SAM phantom) on or off. An MMN was elicited by all deviant types, while its amplitude and latency showed no significant differences due to EMF exposure for any deviant types. In the present study, we found no conclusive evidence that acute exposure to GSM mobile phone EMF affects cortical auditory change detection processing reflected by the MMN. Bioelectromagnetics 30:241–248, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
110.