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611.
为了满足太湖地区农村污水处理占地面积小、除磷脱氮效率高、管理简单、运行和建设费用低的要求,研发了厌氧-跌水充氧接触氧化-人工湿地的组合工艺,并进行了工程试验研究.重点研究了跌水充氧接触氧化的设计及运行参数;接触氧化池内采取弹性填料与组合填料以1:1的比例混合装填,平面布置密度为45根/m2时,可使微生物量与跌水充氧能力之间达到平衡;相邻两池间经济有效的跌水高度为0.5 m;竖缝间距5 cm的挡板对水流的分散效果较好,有利于提高充氧效果;水力停留时间越小充氧效果越好,但由此带来的污染物负荷升高又会使污染物去除效果下降,故水力停留时间宜取2.4 h左右. 相似文献
612.
IntroductionThe application of ultrafiltration for producedwater treatment is still costly in terms of energyconsumption and equipment cost compared withconventional water treatment processes. Thehigh-energy consumption comes from the highcirculation velocity, and it is necessary for controllingconcentration polarization and membrane fouling,which still remain a topical problem for an industrialdevelopment of ultrafiltration processes. Membranefouling in ultrafiltration is complex, accumulatio… 相似文献
613.
Roby Ventres‐Pake Matt Nahorniak Natalie Kramer Jennifer ONeal Tim Abbe 《Journal of the American Water Resources Association》2020,56(2):333-347
Large wood (LW) jams are key riverine habitat features that affect hydraulic processes and aquatic habitat. The hydraulic influence of LW jams is poorly understood due to the complexity of fluid dynamics around irregular, porous structures. Here we validated a method for two‐dimensional hydraulic modeling of porous LW jams using the open‐source modeling software Delft3D‐FLOW. We sampled 19 LW jams at three reaches across the Columbia River Basin in the United States. We used computer‐generated porous plates to represent LW jams in the modeling software and calibrated our modeling method by comparing model outputs to measured depths and velocities at validation points. We found that modeling outputs are error‐prone when LW jams are not represented. By representing LW jams as porous plates we reduced average velocity root mean square error (RMSE) values (i.e., improved model accuracy) by 42.8% and reduced average depth RMSE values by 5.2%. These differences impacted habitat suitability index modeling. We found a 15.1% increase in weighted useable area for juvenile steelhead at one test site when LW jams were simulated vs. when they were ignored. We investigated patterns in average RMSE improvements with varying jam size, bankfull obstruction, porosity, and structure type, and river complexity. We also identified research gaps related to field estimation of LW jam porosity and porous structure modeling methods. 相似文献
614.
Christopher J. Woltemade Jinnieth Woodward 《Journal of the American Water Resources Association》2008,44(1):222-234
ABSTRACT: In 2001, the 1.04‐ha Hornbaker wetland in south‐central Pennsylvania was restored by blocking an artificial drainage ditch to increase water storage and hydraulic retention time (HRT). A primary goal was to diminish downstream delivery of nitrate that enters the wetland from a limestone spring, its main source of inflow. Wetland inflow and outflow were monitored weekly for two years to assess nitrate flux, water temperature, pH, and specific conductivity. In Year 2, spring discharge was measured weekly to allow calculation of nitrate loads and hydraulic retention time. Surface runoff was confirmed to be a small fraction of wetland inflows via rainfall‐runoff modeling with TR‐55. The full dataset (n = 102) was screened to remove 13 weeks in which spring discharge constituted < 85% of total inflows because of high precipitation and surface runoff. Over two years (n = 89), mean nitrate‐nitrogen concentrations were 7.89 mg/l in inflow and 3.68 mg/l in outflow, with a mean nitrate removal of 4.19 mg/l. During Year 2 (n = 47), for which nitrate load data were available, the wetland removed an average of 2.32 kg N/day, 65% of the load. Nitrate removal was significantly correlated with HRT, water temperature, and the concentration of nitrate in inflow and was significantly greater during the growing season (5.36 mg/l, 64%) than during the non‐growing season (3.23 mg/l, 43%). This study indicates that hydrologic restoration of formerly drained wetlands can provide substantial water quality benefits and that the hydrologic characteristics of spring‐fed wetlands, in particular, support effective nitrogen removal. 相似文献
615.
Gregory V. Wilkerson 《Journal of the American Water Resources Association》2008,44(1):243-257
Abstract: Knowledge of bankfull discharge (Qbf) is essential for planners, engineers, geomorphologists, environmentalists, agricultural interests, developments situated on flood prone lands, surface mining and reclamation activities, and others interested in floods and flooding. In conjunction with estimating Qbf, regionalized bankfull hydraulic geometry relationships, which relate Qbf and associated channel dimensions (i.e., width, depth, and cross‐section area) to drainage basin area (Ada), are often used. This study seeks to improve upon the common practice of predicting Qbf using Ada exclusively. Specifically, we hypothesize that predictions of Qbf can be improved by including estimates of the 2‐year recurrence‐period discharge (Q2) in regression models for predicting Qbf. For testing this hypothesis, we used Qbf estimates from 30 reports containing data for streams that span 34 hydrologic regions in 16 states. Corresponding values of Q2 and Ada were compiled from flood‐frequency reports and other sources. By comparing statistical measures (i.e., root mean squared error, coefficient of determination, and Akaike’s information criterion), we determined that predicting Qbf from Q2 rather than Ada yields consistently better estimates of Qbf. Other principal findings are (1) data are needed for at least 12 sites in a region for reliable hydraulic geometry model selection and (2) an approximate range of values for Qbf/Q2 is 0.10‐3.0. 相似文献
616.
617.
Use of tandem circulation wells to measure hydraulic conductivity without groundwater extraction 总被引:2,自引:1,他引:1
Goltz MN Huang J Close ME Flintoft MJ Pang L 《Journal of contaminant hydrology》2008,100(3-4):127-136
Conventional methods to measure the hydraulic conductivity of an aquifer on a relatively large scale (10-100 m) require extraction of significant quantities of groundwater. This can be expensive, and otherwise problematic, when investigating a contaminated aquifer. In this study, innovative approaches that make use of tandem circulation wells to measure hydraulic conductivity are proposed. These approaches measure conductivity on a relatively large scale, but do not require extraction of groundwater. Two basic approaches for using circulation wells to measure hydraulic conductivity are presented; one approach is based upon the dipole-flow test method, while the other approach relies on a tracer test to measure the flow of water between two recirculating wells. The approaches are tested in a relatively homogeneous and isotropic artificial aquifer, where the conductivities measured by both approaches are compared to each other and to the previously measured hydraulic conductivity of the aquifer. It was shown that both approaches have the potential to accurately measure horizontal and vertical hydraulic conductivity for a relatively large subsurface volume without the need to pump groundwater to the surface. Future work is recommended to evaluate the ability of these tandem circulation wells to accurately measure hydraulic conductivity when anisotropy and heterogeneity are greater than in the artificial aquifer used for these studies. 相似文献
618.
采用SCMT型自旋传质生物载体填料处理城市污水,对比研究结果表明:SCMT型自旋传质生物载体填料具有良好的传质性能,在停留时间为1.0 h,气水比为4∶1的情况下,反应器出水水质能够达到《城镇污水处理厂污染物排放标准(GB18918-2002)》中规定的二级标准. 相似文献
619.
620.
超滤膜-生物反应器处理生活污水及其水力学研究 总被引:25,自引:3,他引:22
用超滤膜-生物反应器进行处理生活污水试验并研究其水力学行为。结果表明,当HRT为5h、SRT为30d、膜面流速为4m/s膜流量为75L/(m^2·h)时,试验出水水质优于建设部生活杂用水水质标准CJ25.1-89,可直接回用。 相似文献