全文获取类型
收费全文 | 302篇 |
免费 | 30篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 1篇 |
综合类 | 9篇 |
化学工业 | 6篇 |
金属工艺 | 3篇 |
机械仪表 | 3篇 |
建筑科学 | 51篇 |
矿业工程 | 4篇 |
能源动力 | 2篇 |
轻工业 | 2篇 |
水利工程 | 90篇 |
无线电 | 20篇 |
一般工业技术 | 3篇 |
冶金工业 | 24篇 |
原子能技术 | 1篇 |
自动化技术 | 126篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 21篇 |
2010年 | 21篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 28篇 |
2006年 | 30篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
101.
Ouyang Y 《Water research》2003,37(4):823-832
Naturally occurring total organic carbon (TOC) is an important feature of stream water quality. This study investigates the dynamic load of TOC from the deep creek watershed into the lower St. Johns River (LSJR), FL, USA, using numerical simulations and field measurements. An existing St. Johns River watershed assessment model for simultaneous loading of nutrients from watersheds into rivers is modified to include the TOC component for the purpose of this study. Three simulation scenarios (i.e., daily, monthly, and annually) are performed to estimate the dynamic load of TOC in response to rainfall events. Simulations show that rainfall events have decisive effects on TOC loads from the Deep Creek watershed into the LSJR. In general, the highly frequent the rainfall events occur, the higher the TOC loads into the river. Simulations also illustrate that effects of rainfall events on daily changes of TOC are minimal in winter, but are profound in late summer. Results suggest that TOC load into the river is not only a rainfall-driven but also a temperature-driven biological process. 相似文献
102.
103.
The study summarizes the current knowledge on infection and recovery of white-tailed deer and cattle, and integrates this knowledge into the Soil and Water Assessment Tool (SWAT) via a new add-on module SIR (Susceptible - Infected - Recovered) for predicting pathogen transmission between livestock and deer. New processes modeled by the SWAT-SIR model include: (a) seasonal changes in deer population and habitat; (b) resource selection and seasonal changes in foliage consumption by deer; (c) ingestion of pathogens with water, foliage and via grooming soiled hide by deer and grazing cattle; (d) infection and recovery of deer and co-grazing cattle; (e) pathogen shedding by infected animals; (f) survival of pathogens in manure; (g) kinetic release of pathogens from applied manure and fecal material. The model output is linked with ARC-GIS to allow spatial and temporal analysis of pathogen distribution across the watershed for specific land use, weather and management scenarios. 相似文献
104.
Matthew P. Stenson Mark Littleboy Mat Gilfedder 《Environmental Modelling & Software》2011,26(11):1268-1278
Water and salt export to rivers is of particular importance in large catchments, such as Australia’s Murray-Darling Basin, where there are multiple users of the water resource. Comparing estimates of water and salt generated from upland catchments across large areas is difficult due to the lack of a comparable, consistent approach. River routing models are currently used to model water and salt movement along regulated reaches. However methods are still required to predict the individual contributions of water and salt from unregulated upland catchments to feed into these river routing models. The 2CSalt model has been developed to predict monthly water and salt export from these upland catchments. 2CSalt makes use of existing regional data sets such as topography (digital elevation models) and hydrogeology/salinity (Groundwater Flow Systems). 2CSalt was developed using the “TIME” modelling framework which allowed for a rapid development cycle through the reuse of existing and tested components. The results from current applications of the model show a strong match with measured data. 相似文献
105.
This paper evaluates a recently created Soil and Water Assessment Tool (SWAT) calibration tool built using the Windows Azure Cloud environment and a parallel version of the Dynamically Dimensioned Search (DDS) calibration method modified to run in Azure. The calibration tool was tested for six model scenarios constructed for three watersheds of increasing size each for a 2 year and 10 year simulation duration. Results show significant speedup in calibration time and, for up to 64 cores, minimal losses in speedup for all watershed sizes and simulation durations. An empirical relationship is presented for estimating the time needed to calibration a SWAT model using the cloud calibration tool as a function of the number of Hydrologic Response Units (HRUs), time steps, and cores used for the calibration. 相似文献
106.
Erini Stream (Thrace, northeastern Greece) is adversely affected by the presence of an abandoned mixed sulfide mine located in the upper watershed. The GIS based model SWAT (Soil Water and Assessment Tool) was applied to characterize hydrologic processes in the watershed. Model performance was evaluated by comparing the simulation results with field data including flow and concentration measurements from 12 monitoring points, for the time period from June 2005 to July 2006. Flow rate results indicated good agreement between simulated and measured data, with coefficient correlations R2 in the range of 0.74–0.89. Simulation was focused on the dispersion of three pollutants, Zn, Cd and Mn. Using SWAT alone, simulation results systematically overestimated pollutants levels in Erini Stream.Geochemical model PHREEQC was used in combination with SWAT to obtain more accurate predictions regarding contaminants concentrations along the course of Erini Stream. The profiles of main metal contaminants, i.e. Zn, Cd and Mn, under wet conditions, were described with satisfactory precision assuming equilibrium with the carbonate minerals ZnCO3·H2O and otavite and partial supersaturation with respect to rhodochrosite. However, precipitation of discrete carbonate phases does not seem to be the predominant attenuation mechanism under dry conditions. Coprecipitation or sorption on the surface of precipitating calcite is another potential removal mechanism under these conditions.The methodology presented allows the reliable assessment of acid mine drainage impacts in the downstream aquatic environment and the design of effective measures for its mitigation based on an optimized number of monitoring data. 相似文献
107.
Wireless sensor networks are an effective tool to provide fine resolution monitoring of the physical environment. Sensors generate continuous streams of data, which leads to several computational challenges. As sensor nodes become increasingly active devices, with more processing and communication resources, various methods of distributed data processing and sharing become feasible. The challenge is to extract information from the gathered sensory data with a specified level of accuracy in a timely and power-efficient approach. This paper presents a new solution to distributed information extraction that makes use of the morphological Watershed algorithm. The Watershed algorithm dynamically groups sensor nodes into homogeneous network segments with respect to their topological relationships and their sensing-states. This setting allows network programmers to manipulate groups of spatially distributed data streams instead of individual nodes. This is achieved by using network segments as programming abstractions on which various query processes can be executed. Aiming at this purpose, we present a reformulation of the global Watershed algorithm. The modified Watershed algorithm is fully asynchronous, where sensor nodes can autonomously process their local data in parallel and in collaboration with neighbouring nodes. Experimental evaluation shows that the presented solution is able to considerably reduce query resolution cost without scarifying the quality of the returned results. When compared to similar purpose schemes, such as “Logical Neighborhood”, the proposed approach reduces the total query resolution overhead by up to 57.5%, reduces the number of nodes involved in query resolution by up to 59%, and reduces the setup convergence time by up to 65.1%. 相似文献
108.
F. López-Mir V. Naranjo J. Angulo M. Alcañiz L. Luna 《Computer methods and programs in biomedicine》2014
There are few fully automated methods for liver segmentation in magnetic resonance images (MRI) despite the benefits of this type of acquisition in comparison to other radiology techniques such as computed tomography (CT). Motivated by medical requirements, liver segmentation in MRI has been carried out. For this purpose, we present a new method for liver segmentation based on the watershed transform and stochastic partitions. The classical watershed over-segmentation is reduced using a marker-controlled algorithm. To improve accuracy of selected contours, the gradient of the original image is successfully enhanced by applying a new variant of stochastic watershed. Moreover, a final classifier is performed in order to obtain the final liver mask. Optimal parameters of the method are tuned using a training dataset and then they are applied to the rest of studies (17 datasets). The obtained results (a Jaccard coefficient of 0.91 ± 0.02) in comparison to other methods demonstrate that the new variant of stochastic watershed is a robust tool for automatic segmentation of the liver in MRI. 相似文献
109.
The concrete channel of the Los Angeles (LA) River is probably one of the most recognizable rivers in the world. Channelized to manage the risk of flooding as the Los Angeles region urbanized, the river today is an architectural and engineering feat in the eyes of some people but an ecological disaster to others. The river flows adjacent to 17 cities and among some of the most environmentally burdened, park poor, and underserved communities of LA County. With over 2,300 acres of largely publicly owned land within the river right-of-way, a reimagined LA River can impact the lives of the one million people that live within a mile of the river. The LA River Master Plan, led by Los Angeles County and scheduled to be completed in fall 2021, proposes 51 miles of connected public open space with multi-benefit projects supporting nine goals ranging from flood resilience to housing affordability, to ecological function, and to arts, education, and culture. The data-based plan for the next 25 years includes a watershed-wide research effort to document and understand water quality, water conservation, and flood risk in relation to environmental and social issues. The plan includes traditional and innovative strategies within a “kit of parts,” interventions that include over 65 components ranging from habitat bridges to dry arroyo side channels demonstrating opportunities for enhancing ecosystem services to create a thriving urban habitat and connected network of parks along the river. 相似文献
110.