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141.
Evaporation from porous rock plays an important role in weathering processes. In the case of salt weathering, the evaporation rate controls supersaturation of salt solutions within pores and the amount of precipitated aggressive salts, therefore weathering occurs mostly in places with intense evaporation. Evaporation also strongly affects frost, hydric and biogenic weathering, as these are influenced by water content and its temporal changes. Despite its importance, evaporation from porous rocks has seen little scientific focus. We present a study on evaporation from bare sandstone, one of the most common rocks affected by weathering. A new method that measures the evaporation rate from the surfaces of sandstone samples under field microclimate was developed and tested. Also, a simple calculation of 1D evaporation rate from bare sandstone surfaces based on Fick's law of diffusion is presented. The measurement was performed using sandstone cores (with a set depth of the vaporization plane) in a humid continental climate and measured on a roughly monthly interval for about 1 year. For the calculations, a laboratory-measured water-vapour diffusion coefficient of the sandstone, in-situ seasonally measured vaporization plane depth, and values of air humidity and temperature were used. The sensitivity analyses showed that the most important factor controlling the evaporation rate was the vaporization plane depth, while seasonal and spatial changes of air humidity and temperature were of lesser importance. The calculated evaporation rate reasonably follows measured values. For its simplicity and the small number of parameters required, the proposed method has the potential to improve knowledge of weathering and living conditions of endolithic and epilithic organisms. Further research should focus on factors affecting the evaporation rate (wind, hygroscopicity, hydrophobicity, etc.) to improve the accuracy of the calculations, as well as to test the applicability of the method for other lithologies and climates. © 2020 John Wiley & Sons, Ltd.  相似文献   
142.
Abstract— Near‐Earth object (NEO) research plays an increasingly important role not only in solar system science but also in protecting our planetary environment as well as human society from the asteroid and comet hazard. Consequently, interest in detecting, tracking, cataloguing, and the physical characterizing of these bodies has steadily grown. The discovery rate of current NEO surveys reflects progressive improvement in a number of technical areas. An integral part of NEO discovery is astrometric follow‐up crucial for precise orbit computation and for the reasonable judging of future close encounters with the Earth, including possible impact solutions. The KLENOT Project of the Klet Observatory (South Bohemia, Czech Republic) is aimed especially at the confirmation, early follow‐up, long‐arc follow‐up, and recovery of near‐Earth objects. It ranks among the world's most prolific professional NEO follow‐up programs. The 1.06 m KLENOT telescope, put into regular operation in 2002, is the largest telescope in Europe used exclusively for observations of minor planets and comets, and full observing time is dedicated to the KLENOT team. In this paper, we present the equipment, technology, software, observing strategy, and results of the KLENOT Project obtained during its first phase from March 2002 to September 2008. The results consist of thousands of precise astrometric measurements of NEOs and also three newly discovered near‐Earth asteroids. Finally, we also discuss future plans reflecting also the role of astrometric follow‐up in connection with the modus operandi of the next generation surveys.  相似文献   
143.
Widespread agricultural activity may threaten water quality in fractured bedrock aquifers having little overburden protection. A study in Canada improves the understanding of the potential impact of agriculture on water quality in bedrock aquifers, focusing on spatial and temporal variability of nitrate and bacteria. A research site was developed in and adjacent to a hay field where a gneissic aquifer is overlain by a thin veneer of unconsolidated glacial material. Ten wells were installed, hydraulically tested and completed as multilevel piezometers. Results of monthly sampling for nitrate, dissolved organic carbon, and E. coli show significant temporal and spatial variation in concentrations. Intensive 5-day sampling rounds conducted during baseflow and recharge conditions indicate that bacterial concentrations vary daily, with higher concentrations during recharge periods. The location of the impacted monitoring wells is correlated to an upgradient cattle pasture that is used periodically each summer. It is evident that periodic upgradient sources, dilution from recharge, and heterogeneous flow systems lead to varied and unpredictable contaminant concentrations. The temporal and spatial variability of contaminants in bedrock aquifers with minimal overburden must be considered for the protection of human health, as annual or even monthly groundwater monitoring may not capture unsafe concentrations.  相似文献   
144.
145.
In recent years a body of literature has arisen on the topic of how to compose the optimal portfolio of mitigation options. The focus has been mainly on options involving shifts from high- to low- or even negative-carbon technologies. Natural sinks play an important role in any attempt to stabilize atmospheric CO2 and usually enter as a constant term in the overall carbon budget. In this paper, we introduce natural sinks to the carbon management problem and analyze the implications for negative emission technology deployment and the overall mitigation strategy. Amongst other sensitivity analyses, we also investigate the impact of uncertainty in the carbon sink, which we find to raise the importance of negative emissions in the mitigation portfolio significantly lowering the cost of the policy mix.  相似文献   
146.
All recent available data sets containing traveltimes of Pg and Sg phases for the Moravo-Silesian region were collected. These data come from several experiments designed mostly in 2D (in-line) configurations. Simultaneous processing of all data is possible only considering the true 3D measurement geometry. The goal of this work is to establish the representative 3D seismic model by means of seismic tomography. The resulting minimum-structure model is presented in a simple and easy to use form on the Internet. The amount of processed data is relatively low but repeating the computations with new experimental data included would be very easy. Important material related to this paper is placed on web pages.  相似文献   
147.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   
148.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   
149.
Digha coastal region in the northeastern part of the Bay of Bengal is potentially vulnerable to erosional hazard. The present study assessed the coastal erosion vulnerability along this 65 km long coastal stretch located between Rasulpur (Midnapur) and Subarnarekha (Balasore) estuarine complex, which had been subjected to anthropogenic intervention. Multi-resolution Landsat satellite imagery were used for shoreline change study from 1972 to 2010. During this period, accretion was recorded updrift of artificial structures, viz, seawall, groin, pylons and jetties; while, extensive erosion was recorded in downdrift areas of these structures. Assessment was subsequently divided into four categories ranging from “high erosion” to “accretion”. Data from several sources were compiled to map landuse and human activities in the coastal zone. This map was divided into four categories, ranging from “very high capital” to “no capital” landuse. Population density map of the surrounding coastal villages was generated using census data, and divided into four categories ranging from “high density area” to “very low density area”. Subsequently, coastal erosion vulnerability was assessed by combining coastal retreat with landuse type and population density in this study area using simple vector algebraic technique. Zones of vulnerability of different magnitude (viz., very high, high, moderate, and low) have been identified. Furthermore, calculation of “imminent collapse zone (ICZ)” shows that maximum values are around artificial structures and anthropogenic activities. The coastal erosion vulnerability map prepared from this study can be used for proper planning and management of this coastal region.  相似文献   
150.
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