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101.
Water resources, and in particular run-off, are significantly affected by climate variability. At present, there are few examples of how the water management sector integrates information about changing intra-annual climate conditions in a systematic manner in developing countries. This paper, using the case study of Cape Town in the Western Cape, South Africa, identifies processes and products to facilitate increased uptake of seasonal climate forecasts among water resource managers. Results suggest that existing seasonal forecasts do not focus enough on specific users’ needs. In order to increase uptake, forecasts need to include information on the likely impact of precipitation variability on runoff and water availability. More opportunities are also needed for those with climate knowledge to interact with water resource managers, particularly in the developing country context where municipal managers’ capacity is strained. Although there are challenges that need to be overcome in using probabilistic climate information, seasonal forecast information tailored to the needs of water resource planners has the potential to support annual planning and is therefore a means of adapting to climate change.  相似文献   
102.
The specter of climate change threatens fresh water resources along the U.S.–Mexico border. Water managers and planners on both sides of the border are promoting desalination—the conversion of seawater or brackish groundwater to fresh water—as an adaptation response that can help meet growing water demands and buffer against the negative impacts of climate change on regional water supplies. However, the uneven distribution of costs and benefits of this expensive, energy-intensive technology is likely to exacerbate existing social inequalities in the border zone. In this paper, we examine the discourses employed in the construction of the climate problem and proposed solutions. We focus our analysis on a proposed Arizona–Sonora binational desalination project and use insights from risk and hazards literature to analyze how, why, and to what effect desalination is emerging as a preferred climate change adaptation response. Our risk analysis shows that while desalination technology can reduce some vulnerabilities (e.g., future water supply), it can also introduce new vulnerabilities by compounding the water-energy nexus, increasing greenhouse gas emissions, inducing urban growth, producing brine discharge and chemical pollutants, shifting geopolitical relations of water security, and increasing water prices. Additionally, a high-tech and path-dependent response will likely result in increased reliance on technical expertise, less opportunity for participatory decision-making and reduced flexibility. The paper concludes by proposing alternative adaptation responses that can offer greater flexibility, are less path dependent, incorporate social learning, and target the poorest and most vulnerable members of the community. These alternatives can build greater adaptive capacity and ensure equity.  相似文献   
103.
Chick  L. M.  De Lange  W. P.  Healy  T. R. 《Natural Hazards》2001,24(3):309-318
Geophysical data have identified four submarine segments of the Kerepehi Fault, roughly bisecting a back-arc rift (Hauraki Rift). These segments have been traced through the shallow waters of the Firth of Thames, which lies at the southern end of the Hauraki Gulf, New Zealand. No historical or paleotsunami data are available to assess the tsunami hazard of these fault segments.Analysis of the fault geometry, combined with paleoseismic data for three further terrestrial segments of the Fault, suggest Most Credible Earthquake (MCE) moment magnitudes of 6.5–7.1. Due to the presence of thick deposits of soft sediment, and thesemi-confined nature of the Firth, the MCE events are considered capable of generating tsunami or tsunami-like waves. Two numerical models (finite element and finite difference), and an empirical method proposed by Abe (1995), were used to predict maximum tsunami wave heights. The numerical models also modelled the tsunami propagation.The MCE events were found not to represent a major threat to the large metropolitan centre of Auckland City (New Zealand's largest population centre). However, the waves were a threat to small coastal communities around the Firth, including the township of Thames, and 35,000 ha of low-lying land along the southern shores of the Firth of Thames.The Abe method was found to provide a quick and useful method of assessing the regional tsunami height. However, for sources in water depths < 25 m the Abe method predicted heights 2–4 times larger than the numerical models. Since the numerical models were not intended for simulating tsunami generation in such shallow water, the Abe results are probably a good guide to the maximum wave heights.  相似文献   
104.
The composition of the Pyrgulidae and its relationships to other member families of the caenogastropod superfamily Rissooidea are examined after a consideration of new anatomical (including gross anatomy, sperm ultrastructure), conchological (including protoconch features), ecological, biogeographical and palaeontological data and a re-evaluation of existing literature. Pyrgulidae can be distinguished from hydrobiids unequivocally only with the aid of the radula. Sperm ultrastructural features suggest a very close relationship between the Pyrgulidae, the Hydrobiidae and the Bithyniidae (in fact no family-diagnostic sperm characters can be found to separate these three taxa). Based upon neontological and fossil evidence it is likely that pyrgulids represent a Miocene offshoot from a paratethyal hydrobiid lineage. Pyrgulids may also represent the stock from which the baicaliids arose, in which case the Pyrgulidae must be considered a paraphyletic group. The huge biogeographic gap between the Caspian Sea and Lake Baikal is to some extent bridged by the finding of a Neogene pyrgulid from the Altai Mountains. An alternative scenario for the origin of baicaliids is presented.  相似文献   
105.

Four meadows of turtle grass (Thalassia testudinum Banks ex Konig) in Sarasota Bay, Florida were sampled on a bimonthly basis from June 1992 to July 1993 to determine spatial and temporal variation in short shoot density, biomass, productivity, and epiphyte loads. Concurrent with the seagrass sampling, quarterly water-quality monitoring was undertaken at ≥3 sites in the vicinity of each studied seagrass meadow. Three months after termination of the seagrass sampling effort, a biweekly water-quality monitoring program was instituted at two of the seagrass sampling sites. In addition, a nitrogen loading model was calibrated for the various watersheds influencing the seagrass meadows. Substantial spatial and temporal differences in turtle grass parameters but smaller spatial variation in water quality parameters are indicated by data from both the concurrent quarterly monitoring program and the biweekly monitoring program instituted after termination of the seagrass study. Turtle grass biomass and productivity were negatively correlated with watershed nitrogen loads, while water quality parameters did not clearly reflect differences in watershed nutrient inputs. We suggest that traditional water-quality monitoring programs can fail to detect the onset or continuance of nutrient-induced declines in seagrass health. Consequently, seagrass meadows should be monitored directly as a part of any effort to determine status and/or trends in the health of estuarine environments. *** DIRECT SUPPORT *** A01BY074 00029

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106.
Mining operations in Palawan, Philippines, resulted in cinnabar (HgS) mine tailings being used to build a 600 m long peninsula in Honda Bay. Samples collected from the peninsula as well as sediments from the surrounding waters had elevated mercury levels as high as 570 ppm. Natural processes are transporting mercury as much as 10 km from the peninsula, mainly in a coastwise direction, and preferentially associated with fine-grained, organic-rich sediments. Depth of penetration into sediments exceeds 10 cm near the source. As the HgS is transported away from the peninsula, it is rapidly altered to more bioavailable forms; 50% conversion occurs within a distance of only 10–40 m.  相似文献   
107.
108.
An examination was made of the genetic variation with age in mangrove populations in two estuaries in south-east Australia, one contaminated, the other uncontaminated. Sediment nutrient and metal levels, and isozyme/allozyme complements were measured in three age-classes in four stands in each estuary, to identify site and intergenerational genetic composition, and influences of sediment contamination. Within each river, there were greater genetic distances among the age-classes than among sampling sites. A downstream gradient of genetic distance was found in the uncontaminated river, but not the contaminated one, where genetic distances seemed to reflect site-specific factors, though apparently not the present sediment metal or nutrient levels. It appears that genetic distances in the polluted river may reflect past fluctuations in pollution pressures. In both rivers, genetic distances indicate that the mangroves within one estuary form one population, with 'neighbourhood' differentiation.  相似文献   
109.
Iron powder, a promising dry-cleansing agent for oiled feathers where both the contaminant and the cleansing agent may be harvested magnetically, has been tested on the plumage of whole-bird models. The breast and back plumage of Mallard Duck (Anas platyrhynchos) and Little Penguin (Eudyptula minor) carcasses were patch-contaminated with commercial-grade engine oil, three different crude oils, and an oil/seawater emulsion. The plumage was then subjected to a magnetic cleansing protocol. The contaminant removal was assessed gravimetrically and was found to reflect the outcomes for a previously reported in vitro study using feather clusters. Between 92-98% of the contaminants, and effectively all of the cleansing agent, were removed from the feathers.  相似文献   
110.
Margaret Desmond 《Area》2004,36(3):262-269
This paper engages with recent debates in geography and associated disciplines that are concerned with the wider analytic issues to be confronted in researching an elite. Drawing on a case study of the construction of a policy position on GMOs and the Environment in Ireland, the methodological challenges encountered researching up the hybrid elite central to this development are interrogated. In particular, emphasis is placed on the politics of time, which becomes central when a new sector is emerging, and meanings and definitions are being constructed.  相似文献   
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