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91.
92.
Journal of Mathematical Biology - In this paper we introduce a formal method for the derivation of a predator’s functional response from a system of fast state transitions of the prey or...  相似文献   
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The intricate interplay between predators and prey has long fascinated ecologists, with bats and their diverse prey offering insight into co-evolutionary dynamics. While bats have evolved sophisticated strategies for prey capture, they also face predation pressure. Among their predators, spiders stand out for their diversity of predatory tactics, ranging from hunting assaults and web ensnarement to the deployment of venom. Yet, bat predation records by spiders are mostly from tropical regions, and cases remain notably scarce in temperate regions. Here, we report four new incidences of bat predation and mortality by spiders and their webs in Europe. Our observations include detailed photograph and video documentation of the first record of a spider capturing and consuming a bat pup in Spain, as well as accounts of bats entangled in spider webs on a building and inside bat boxes in the United Kingdom. These findings shed light on understudied predator–prey dynamics, offering valuable insights into spider predation on bats in European ecosystems. Our study emphasises the importance of continued research to improve our understanding of ecological interactions between these elusive and primarily nocturnal taxa.  相似文献   
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  1. Understanding processes driving patterns of species distribution and diversity is one of the main objectives of community ecology.
  2. The aim of our study was to evaluate the spatial variation in assemblage composition of stream-dwelling macroinvertebrates and identify which factors (e.g. water quality, land cover) are the most important drivers.
  3. We applied the elements of the metacommunity structure approach on a dataset of 38 communities from the Futaleufú basin in northwestern Patagonia. To better understand assemblage variation, we deconstructed our macroinvertebrate dataset into different taxonomic and trait groups. We then identified the most influential factors driving community composition using random forests.
  4. We found that half of our datasets (i.e. macroinvertebrate groups) exhibited a nested structure with clumped species loss, while the other half showed a quasi-nested pattern with either clumped or stochastic species loss.
  5. Overall, water quality was the most important driver of community variation, although climate, geography, and land cover were more or less relevant in particular cases. We found differences in the relative importance of the selected explanatory variables among datasets. This would suggest that different components of the macroinvertebrate community respond differently to environmental factors.
  6. Our findings could be of value for conservation planning, as they suggest that preserving the most species-rich streams would, to some extent, guarantee the conservation of the entire species pool.
  相似文献   
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We studied two populations of Boeckella gracilipes and two populations of Boeckella gibbosa that inhabit mountain lakes from North‐Patagonian Andes with different optical properties. We combined field and laboratory experiments to determine the effects of ultraviolet radiation (UVR) on clearance rate among these taxa that had different UVR defences. The copepod populations differed in photoprotective compounds (carotenoids and mycosporine‐like amino acids [MAAs]) and antioxidant enzymes (glutathione S‐transferase [GST]). These variations were related to elevation, dissolved organic carbon content and the optical features of the inhabited lakes. Laboratory experiments showed a decrease in the clearance rate (CR) in all populations exposed to UVR. Consistently, the long‐term field experiment showed a negative impact of UVR on CR. We conclude that UVR exposure affects feeding, however, the magnitude of this negative effect depends on the exposure intensity and the photoprotective mechanisms used by zooplankton.  相似文献   
97.
SF162 is a primary (PR), non-syncytium-inducing, macrophagetropic human immunodeficiency virus type 1 (HIV-1) clade B isolate which is resistant to antibody-mediated neutralization. Deletion of the first or second hypervariable envelope gp120 region (V1 or V2 loop, respectively) of this virus does not abrogate its ability to replicate in peripheral blood mononuclear cells and primary macrophages, nor does it alter its coreceptor usage profile. The mutant virus with the V1 loop deletion, SF162ΔV1, remains as resistant to antibody-mediated neutralization as the wild-type virus SF162. In contrast, the mutant virus with the V2 loop deletion, SF162ΔV2, exhibits enhanced susceptibility to neutralization by certain monoclonal antibodies whose epitopes are located within the CD4-binding site and conserved regions of gp120. More importantly, SF162ΔV2 is now up to 170-fold more susceptible to neutralization than SF162 by sera collected from patients infected with clade B HIV-1 isolates. In addition, it becomes susceptible to neutralization by sera collected from patients infected with clade A, C, D, E, and F HIV-1 isolates. These findings suggest that the V2, but not the V1, loop of SF162 shields an as yet unidentified region of the HIV envelope rich in neutralization epitopes and that the overall structure of this region appears to be conserved among clade B, C, D, E, and F HIV-1 PR isolates.  相似文献   
98.
A protocol is described for rapid DNA isolation from Malvaceae plant species and different tissues of Bixaceae that contain large amounts of polysaccharides, polyphenols, and pigments that interfere with DNA extractions. The method is a modification of Dellaporta et al. The current protocol is simple, and no phenolchloroform extraction, ethanol, or isopropranol precipitation is required. The method is based in the incubation of soluble DNA with silica, mix in batch during the extraction. The procedure can be completed in 2 h and many samples can be processed at the same time. DNA of excellent quality was recovered and used for polymerase chain reaction (PCR) amplification, restriction enzyme digestion, and Southern blot analysis. The method was used with healthy Bixa orellana and virus-infected Malvaceae plants.  相似文献   
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Two exopolysaccharide (EPS)-producing strains of the diatom Navicula, were isolated from benthic and pelagic mucilaginous aggregates sampled in the Tyrrhenian Sea and cultured under laboratory conditions. The amount of carbohydrate formed over the growth period and on a per cell basis was quite similar. However, the benthic strain showed a preferential synthesis of the bound (i.e., cellular and capsular) carbohydrate fraction, whereas the pelagic strain preferentially synthesised soluble, polymeric carbohydrates. The polysaccharides released into the medium by the two strains showed the same qualitative monosaccharidic composition, being constituted by two acidic and six neutral sugars. It is suggested that the difference between the benthic and the pelagic strain in the synthesis of bound or soluble carbohydrates may be related to the different role of these compounds in the particular habitats of the strains.  相似文献   
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