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991.
For over a thousand years many settlements in Korea forbid the digging of water‐wells. This custom can be explained using geomancy, which personifies local landscapes or names them after animate or inanimate objects. In ‘sailing boat’ landscapes the digging of water‐wells was prohibited because this was viewed as analogous to making a hole in the bottom of a boat, which would thus bring misfortune to local residents. Based on this geomantic reasoning, people considered the custom of forbidding well digging to be an integral part of the art of geomancy, with its origin in a geomantic belief system. My earlier research sustained this explanation but this paper, which is based on two recent instances of field work, rejects the established view on the custom. The aim of this paper is to critically re‐examine this established view and suggests a new idea that the folk custom of prohibiting well digging in Korea was not originally derived from geomancy, but was conceived from a non‐geomantic indigenous Korean idea and have become linked to geomancy through the enforcement process of practicing the custom in traditional Korean society.  相似文献   
992.
Fine particles may infiltrate through coarse alluvial beds and eventually saturate the subsurface pore space. It is essential to understand the conditions that lead to bed saturation, and to forecast the packing characteristics of saturated beds to assess the effect of excess fine sediment supply on a number of processes that occur in the stream–sediment boundary. To address this problem, in this study, a new method is introduced to predict the grain‐size distribution for the saturated condition, and the resulting porosity decrease, given the characteristics of the bed and the supplied sediments. The new method consists of the numerical aggregation of infilling fines in a finite bed volume, during which the bed properties change to affect further infilling. An existing semi‐empirical, particle packing model is implemented to identify these properties. It is shown that these types of models are adequate to describe regimes of natural sediment fabric quantitatively, and are thus useful tools in the analysis of sediment infiltration processes. Unlike previous developments to quantify saturated bed conditions, which assume that the supplied material is uniform and finer than the bed pore openings, the method developed herein considers poorly sorted fines, and can identify size fractions that are able to ingress into the bed due to being smaller than the particles that form the bed structure. Application of the new method to published experimental data showed that the final content of infiltrated fines is strongly sensitive to the initial bed packing density, highlighting the need to measure and understand open‐work gravel deposits. In addition, the new method was shown to be suitable for assessing the degree of bed saturation, when it was applied to a published data set of field samples.  相似文献   
993.
Laboratory and field experiments done on fractured rock show that flow and solute transport often occur along flow channels. ‘Sparse channels’ refers to the case where these channels are characterised by flow in long flow paths separated from each other by large spacings relative to the size of flow domain. A literature study is presented that brings together information useful to assess whether a sparse-channel network concept is an appropriate representation of the flow system in tight fractured rock of low transmissivity, such as that around a nuclear waste repository in deep crystalline rocks. A number of observations are made in this review. First, conventional fracture network models may lead to inaccurate results for flow and solute transport in tight fractured rocks. Secondly, a flow dimension of 1, as determined by the analysis of pressure data in well testing, may be indicative of channelised flow, but such interpretation is not unique or definitive. Thirdly, in sparse channels, the percolation may be more influenced by the fracture shape than the fracture size and orientation but further studies are needed. Fourthly, the migration of radionuclides from a waste canister in a repository to the biosphere may be strongly influenced by the type of model used (e.g. discrete fracture network, channel model). Fifthly, the determination of appropriateness of representing an in situ flow system by a sparse-channel network model needs parameters usually neglected in site characterisation, such as the density of channels or fracture intersections.  相似文献   
994.
The state-of-the-art monitoring of drinking water hygiene is based on the cultivation and enumeration of indicator bacteria. Despite its proven reliability, this approach has the disadvantages of being (a) relatively slow and (b) limited to a small number of indicator bacteria. Ideally, alternative methods would be less time-consuming while providing information about a larger set of hygienically relevant microorganisms including viruses. In this paper, we present insights into the design of a modular concentration and detection system for bacteria, bacteriophages and viruses. Following further validation, this or similar techniques have the potential to extend and speed up the monitoring of raw and drinking water hygiene in the future. The system consists of different modules for the concentration of microorganisms, an amplification and detection unit that includes a module for the differentiation between live and dead microorganisms, and an automated system for decision support and self-diagnosis. The ongoing testing under controlled laboratory conditions and real-life conditions in the water supply industry yields further system improvements. Moreover, the increased sensitivity and broader range of microbiological parameters emphasize the need for a reconsideration of the currently used criteria for the assessment of (drinking) water hygiene.  相似文献   
995.
Coral reefs are in crisis worldwide. Fish play a key role in the resilience of reefs because most of the biomass of the ecosystem flows through them. Evidence indicates that the response to stressors will vary markedly depending on the resilience of the ecosystem. In order to assess the functional groups of reef fishes, morphometric and ecomorphological analyses were carried out on the shape and diet of 117 reef fish species from the Mexican Eastern Pacific (MEP) from 23°N to 15°N, spanning the years 2009–2012. Six trophic groups were identified and subdivided into 19 functional groups: (A) detritus and plants consumers, three morphologies; (B) plants and zoobenthos consumers, four morphologies; (C) zoobenthos consumers, two morphologies; (D) zoobenthos and zooplankton consumers, three morphologies; (E) zooplankton and nekton consumers, three morphologies; and (F) nekton consumers, four morphologies. Our main conclusions are: (i) fish communities of the MEP have a high degree of ecological redundancy; (ii) fish diversity is not related to the coral cover; and (iii) the combination of using both morphology and diet produce a more effective classification of functional groups. Future studies such as these will allow a deeper understanding of environment and it will help illuminate the effects of fish morphology and diet on population structure.  相似文献   
996.
Coral diseases are currently playing a major role in the worldwide decline in coral reef integrity. One of the coral species most afflicted by disease in the Caribbean, and which has been the focus of much research, is the sea fan Gorgonia ventalina. There is, however, very little information regarding the capacity of sea fans to recover after being infected. The aim of this study was to compare the rehabilitation capacity of G. ventalina after diseased‐induced lesions were eliminated either by scraping or extirpating the affected area. Scraping consisted of removing any organisms overgrowing the axial skeleton from the diseased area as well as the purple tissue bordering these overgrowths using metal bristle brushes. Extirpation consisted of cutting the diseased area, including the surrounding purpled tissue, using scissors. The number of scraped colonies that fully or partially rehabilitated after being manipulated and the rates at which the sea fans whose lesions were scrapped grew back healthy tissue were compared among: (i) colonies that inhabited two sites with contrasting environmental conditions; (ii) colonies of different sizes and (iii) colonies with different ratios of area of legions to total colony area (LA/CA). Both strategies proved to be very successful in eliminating lesions from sea fans. In the case of scraping, over 51% of the colonies recovered between 80% and 100% of the lost tissue within 16 months. The number of colonies that recovered from scraping was similar among sites and among colony sizes, but differed significantly depending on the relative amount of lesion to colony area (LA/CA). When lesions were extirpated, lesions did not reappear in any of the colonies. We conclude that lesion scraping is useful for eliminating relatively small lesions (i.e. LA/CA < 10%), as these are likely to recover in a shorter period of time, whereas for relatively large lesions (LA/CA ≥ 10%) it is more appropriate to extirpate the lesion.  相似文献   
997.
Siphonaria pectinata is a marine gastropod distributed across the shores of the Western and Eastern Atlantic. Although previous studies have indicated that the species could be a recent introduction to Central and North America from Western Africa and Europe, other authors have questioned this statement. In fact, a recent study has shown that individuals from both sides of the Atlantic are genetically disconnected, rejecting the idea of a recent invasion. However, genetic information on this species is very scarce and based only on a single study using a limited number of specimens and sites. The data reported in the present study represent one step forward, collecting information from 119 specimens from 22 sites that cover the entire distributional range of the species. Populations from the Western Atlantic separated from eastern ones around 1.4?1.9 Mya, whereas the centre of dispersion is located on the eastern side of the Atlantic. Siphonaria pectinata should be considered native to the Western Atlantic and cannot be considered as a species with an amphi‐atlantic distribution owing to the lack of genetic connection between both sides of the Atlantic, as previous authors have pointed out. The presence of a star‐shaped phylogeny is discussed in the context of Plio‐Pleistocene glaciations.  相似文献   
998.
999.
The potential role of microbial consortia on sponge chemistry is well known. However, how environmental factors affect microbial and chemical profiles and how these shifts affect the sponge holobiont are far from being understood. This study experimentally investigated the effect of light on both the concentration of secondary metabolites and the bacterial assemblages of the sponge Aplysina aerophoba. We quantified major brominated alkaloids (BAs) using a high‐performance liquid chromatography system coupled with a UV‐detector and analysed sponge‐associated bacteria using denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. We identified distinct chemical and bacterial profiles between the ectosome and the choanosome of A. aerophoba. The abundance of most secondary metabolites increased regardless of the illumination regime. We found that the probability of occurrence of three microbial phylotypes (operational taxonomic units 84, 86 and 87) was strongly associated with increasing concentrations of three brominated compounds (aerophobin‐1, aplysinamisin‐1 and isofistularin‐3). Although the role of these bacteria remains uninvestigated, these associations between natural products and specific microbial phylotypes outline further hypotheses that will improve our understanding of the organization and functioning of these complex host–symbiont interactions.  相似文献   
1000.
Marine plants provide a variety of functions with high economic and ecological values in ecosystems. The above‐ (AG) and below‐ground (BG) systems increase the structural complexity of plants, which also enhance faunal abundance and diversity. The ecological role of the AG compartment in structuring inter‐tidal macrobenthic communities has been widely studied; however, this is not the case for the BG compartment. This study addressed the effects of variation in vegetation complexity (in both AG and BG systems) on associated macrobenthic infauna with respect to abundance, species richness, composition, weight and body type. To achieve this aim, a field experiment using artificial vegetation mimics was carried out using replicated treatments with different AG‐BG complexity ratios. We found a significant increase in the density and the number of taxa of macrobenthic infaunal species in plots with vegetation mimics compared with unvegetated areas, regardless of either AG or BG complexity. This effect was found even when AG parts were not present (i.e. when only BG parts were used). Furthermore, a positive relationship between structural complexity and diversity was recorded. Variation in one or both plant compartments was strongly related to diversity changes in the associated macrobenthic infauna. In conclusion, our experimental set‐up provides the first evidence that the BG compartment is at least as important as the AG compartment in controlling diversity in inter‐tidal vegetated areas because it was able to strongly affect community structure even when the AG system was totally absent.  相似文献   
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