首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2407篇
  免费   64篇
  国内免费   226篇
安全科学   111篇
废物处理   242篇
环保管理   262篇
综合类   541篇
基础理论   365篇
环境理论   2篇
污染及防治   842篇
评价与监测   199篇
社会与环境   87篇
灾害及防治   46篇
  2024年   1篇
  2023年   29篇
  2022年   72篇
  2021年   65篇
  2020年   33篇
  2019年   47篇
  2018年   66篇
  2017年   85篇
  2016年   107篇
  2015年   73篇
  2014年   126篇
  2013年   201篇
  2012年   166篇
  2011年   182篇
  2010年   149篇
  2009年   156篇
  2008年   164篇
  2007年   150篇
  2006年   125篇
  2005年   114篇
  2004年   102篇
  2003年   80篇
  2002年   89篇
  2001年   73篇
  2000年   43篇
  1999年   32篇
  1998年   25篇
  1997年   28篇
  1996年   15篇
  1995年   14篇
  1994年   11篇
  1993年   13篇
  1992年   5篇
  1991年   13篇
  1990年   4篇
  1989年   7篇
  1988年   3篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   3篇
  1981年   3篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1965年   1篇
排序方式: 共有2697条查询结果,搜索用时 15 毫秒
41.
本文通过对岷江干流(成都段)地表水和地下水的综合研究,分别提出了地表水污染防治对策和地下水水质防护措施,划分出了地表水防治不同时期的目标以及地下水开采管理目标。  相似文献   
42.
洪水灾害评估体系研究   总被引:28,自引:3,他引:28  
从系统论的观点出发,提出了洪水灾害系统的概念,并结合洪水灾害评估的特点,设计了洪水灾害评估体系的总体框架。  相似文献   
43.
The diagram constructed for selection of sampling methods indicates that, for a systematic error, E ≤ 13%, grab sampling (GS) may be used to characterize effluents with variation coefficient of flow ≤ 120% and of contaminant concentrations ≤ 10%. For the whole studied range of variation coefficient of contaminant concentrations (2–82%), time-proportional compositing (TC) method may be applied with E ≤ 10% for effluents characterized by variation coefficients in flow < 90%. The more complicated flow-proportional compositing (FC) method is required only for effluents with larger variation coefficients or to produce more precise results. The diagram constructed for selection of sampling frequencies indicates that sequential sampling at intervals of approximately 60 min may be applied with E ≤ 10% for effluents characterized by variation coefficients ≤ 30%. Practical application of the diagrams, constructed using normal series, was checked against monitoring data from two pulp and paper mills in Vietnam. The two diagrams provided results on sampling methods and frequencies in good agreement with those obtained from actual monitoring data with percentages of agreement cases of 80 and 75%, respectively. The approach was applied in design of a monitoring program at the Bai Bang integrated pulp and paper mill in Vietnam.  相似文献   
44.
Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker.  相似文献   
45.
Current status and research on E-waste issues in Asia   总被引:2,自引:1,他引:2  
Rapid economic growth in Asia and the increasing transboundary movement of secondary resources will increasingly require both 3R endeavors (reduce, reuse, recycle) in each country and appropriate control of international material cycles. Recently, managing electrical and electronic waste (E-waste) has become an important target for domestic and international material cycles from the viewpoints of environmental preservation and resource utilization efficiency. To understand the current status of E-waste issues in the context of international material cycles and to discuss the future tasks related to achieving 3R in the region, we organized the National Institute for Environmental Studies (NIES) E-waste Workshop in December 2004. This article reviews past studies on E-waste and briefly describes the topics presented and discussions held at the workshop. The topics at the workshop included E-waste generation, recycling systems, international trade, and environmental impacts. In addition, we discussed various issues such as terminology, current environmental concerns, and possible solutions. Transboundary shipments of E-waste should be conducted taking into consideration the concept of sustainable development. The direction of future research and possible collaborations are also discussed.  相似文献   
46.
玉米芯为碳源实现酸性矿山废水生物处理   总被引:9,自引:0,他引:9  
引入了一种新的碳源——玉米芯,对SRB法处理酸性矿山废水进行了更加深入的探索,分析了各种参数条件对s暖一还原效果的影响,确定了常温下这种碳源所需要的最适宜工况条件,探讨了硫酸盐矿山废水的水质资源化问题,并对山西矿山废水的生物治理进行了可行性实验验证。实验证明,玉米芯为碳源时,矿山废水中SO^2-4的出水值可达221.1mg/L,金属离子的浓度也都达到了生活饮用水的质量标准,所以玉米芯可作为酸性矿山废水资源化生物处理的合适有效碳源。  相似文献   
47.
介绍了采用水解-接触氧化工艺处理针织染整废水,工程运行结果表明:CODcr和色度的去除率分别达到91.3%、88%,最终排放污水达到国家污水Ⅰ级标准.该工艺具有处理效果好、经济、运行稳定等特点,在染整废水处理中具有实用性.  相似文献   
48.
Cameron Highlands is a mountainous region with steep slopes. Gradients exceeding 20 are common. The climate is favourable to the cultivation of tea, sub-tropical vegetables and flowers (under rain-shelter). Crop production is sustained by high fertiliser and manure applications. However, agriculture in this environment is characterised by high levels of soil erosion and environmental pollution. A study on the sustainability of these agro-ecosystems was conducted. Results indicated that soil loss was in the range of 24–42 ton/ha/yr under vegetables and 1.3 ton under rain-shelter. Sediment load in the vegetable sub-catchment reached 3.5 g/L, 50 times higher than that associated with flowers under rain-shelter and tea. The sediments contained high nutrient loads of up to 470 kg N/ha/yr. The N, P and K lost in runoff from cabbage farms was 154 kg/season/ha, whereas in chrysanthemum farms it was 5 kg. In cabbage farms, the N, P, and K lost through leaching was 193 kg/season/ha. The NO3–N concentration in the runoff from the cabbage farms reached 25 ppm but less than 10 ppm in runoff from rain-shelters. Inorganic pollution in the rivers was within the acceptable limit of 10 ppm. The sustainability of the agro-ecosystems is in the order of tea { > } rain–shelter ≫ vegetables.  相似文献   
49.
Crop soils, ditch sediments, and water flowing from several farm areas to salmon tributary streams of the Fraser River in the Lower Fraser Valley (LFV) of British Columbia, Canada, were sampled in 2002-2003 to quantify for residues of an organochlorine cyclodiene pesticide, endosulfan (END = alpha-endosulfan + beta-endosulfan + endosulfan sulfate). Residues from historical use of other selected organochlorine pesticides, namely, cyclodienes (aldrin, alpha-chlordane, gamma-chlordane, dieldrin, endrin, endrin aldehyde, heptachlor, and heptachlor epoxide), hexachlorocyclohexanes [alpha-benzene-hexachloride (alpha-BHC), beta-BHC, delta-BHC, and gamma-BHC (lindane)], and DDT-related compounds (p,p-DDT, p,p-DDD, p,p-DDE, and methoxychlor) were also determined. Reference and background levels of these pesticides in ditches leading to fish streams were obtained from pristine watershed areas. Varying amounts of END residues were detected in soils (<0.02-5.60 mg kg(-1) dry wt.) and ditch sediments (<0.02-3.33 mg kg(-1) dry wt.) in mainly three of five farm areas sampled. Likewise, residues (excluding END) of other selected organochlorine compounds such as aldrin, BHC, chlordane, endrin, p,p-DDT, methoxychlor, and their respective major transformation products (endosulfan sulfate, dieldrin, endrin aldehyde, heptachlor, heptachlor epoxide, p,p-DDD, and p,p-DDE) were found in crop soils (<0.02-16.2 mg kg(-1) dry wt.) and sediments (<0.02-9.73 mg kg(-1) dry wt.). Most of these pesticides (END: <0.01-1.86 microg L(-1); other selected organochlorine pesticides: <0.0.1-1.50 microg L(-1)) were also found in ditch water leading to salmon streams in several farms. The END levels of crop soils from the same LFV study farms in 1994 and 2003 indicated an estimated decline of 22% to 1.35 mg kg(-1) dry wt. during that period. This reduction was probably due to the increasing use of alternate pesticides (e.g., organophosphorus compounds). Some possible biological implications of these pesticide residues on nontarget organisms in the LFV are discussed.  相似文献   
50.
This study aimed at finding effective strategies for high-performance removal of reactive blue 19 (RB19) dye from aqueous solution. Chitosan (CS) films had been prepared by using solvent casting with mild drying for this purpose. The CS films were characterized by X-ray diffraction, field-emission scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The performance of RB19 removal using CS were evaluated by varying contact time, solution pH, initial dye concentration, and adsorbent dosage. Adsorption isotherms, kinetics, and desorption were investigated by batch experiments. Results showed that CS films exhibited the optimal adsorption performance for RB19 removal and high maximum adsorption capacities of RB19, which were 799 and 822.4 mg g?1 at 20 and 40 °C, respectively. Adsorption kinetic data were well described by the pseudo-second-order kinetic model. FTIR analyses further indicated that interactions between RB19 and the CS film occurred during adsorption. The CS films also exhibited satisfactory desorption of RB19 at about 80 % after 30 min of desorption at pH 11. Our study demonstrated that the CS films can be easily prepared and applied for effective removal of RB19 in treatment of wastewater.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号