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   13363篇
  免费   113篇
  国内免费   1359篇
安全科学   221篇
废物处理   961篇
环保管理   1509篇
综合类   2815篇
基础理论   3766篇
环境理论   1篇
污染及防治   3230篇
评价与监测   1144篇
社会与环境   1022篇
灾害及防治   166篇
  2023年   66篇
  2022年   189篇
  2021年   129篇
  2020年   99篇
  2019年   90篇
  2018年   1594篇
  2017年   1501篇
  2016年   1339篇
  2015年   333篇
  2014年   318篇
  2013年   370篇
  2012年   787篇
  2011年   1639篇
  2010年   915篇
  2009年   868篇
  2008年   1141篇
  2007年   1439篇
  2006年   210篇
  2005年   173篇
  2004年   147篇
  2003年   204篇
  2002年   228篇
  2001年   125篇
  2000年   131篇
  1999年   132篇
  1998年   152篇
  1997年   85篇
  1996年   77篇
  1995年   76篇
  1994年   60篇
  1993年   55篇
  1992年   48篇
  1991年   15篇
  1990年   19篇
  1989年   11篇
  1988年   12篇
  1987年   5篇
  1986年   6篇
  1985年   2篇
  1984年   14篇
  1983年   10篇
  1982年   2篇
  1981年   7篇
  1979年   2篇
  1977年   2篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1971年   2篇
  1935年   2篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
361.
重点介绍湖州市北污水处理厂采用带式压滤机进行污泥脱水处理的应用情况及运行管理,并进行了小结。  相似文献   
362.
The difficulty in achieving high removal efficiency for contaminants in textile wastewater over a wide range of pH impedes the progress of its treatment technique greatly. Herein, a facile and sustainable strategy was adopted for constructing magnetic ordered mesoporous polymers (M-OMPs) without the assistance of organic solvent and catalyst. The prepared M-OMPs were endowed with high special surface area and good superparamagnetism simultaneously, and exhibited high removal efficiency (>99%) for Methylene Blue (MB) within a short time (10 min) at a concentration of 50 mg/L. What's more, high removal efficiency was achieved over a wide range of pH 2-12 and the adsorption capacity for MB on M-OMPs was substantially retained even after 5 adsorption-desorption cycles, further demonstrating the application potential of M-OMPs in the decontamination of textile wastewater.  相似文献   
363.
陕北子长县阎家沟黄土滑坡特征及其变形机制   总被引:1,自引:1,他引:0  
野外调查和钻探资料显示,阎家沟滑坡属大型黄土滑坡,滑坡体为中、晚更新世黄土.在滑坡前缘流水侵蚀坡脚和滑坡体上修建窑洞、梯田、排放生活用水等人类工程活动影响下以及在2002年7月4日连续强降雨的激发下,目前处于不稳定状态,若遇强降雨失稳概率很大.填埋滑坡体裂隙和孔洞、加强地表排水、在滑坡体前缘沟谷修建淤地坝是提高陕北此类滑坡稳定性最为经济有效的措施.  相似文献   
364.
爆炸物冲击波的人体防护研究   总被引:2,自引:0,他引:2  
针对爆炸物爆炸冲击波、破片或子弹冲击、高温高压气体热辐射等复杂环境下的人体伤害威胁,本文从人员损伤研究和防护材料研究两方面综述了国内外研究进展,最后为开展人体有效防护研究工作提出了几点建议.  相似文献   
365.
针对盾构隧道施工侧穿既有建筑物问题,结合南京地铁一号线北延段工程,以盾构隧道侧穿某浅基础建筑物为研究对象,通过对建筑物沉降实测数据进行分析,并利用Plaxis 3D 软件建立数值模型,研究了隧道距建筑物不同水平距离和盾构以不同角度穿越对建筑物差异沉降与扭曲变形特征的影响。结果表明:随着盾构开挖面逐渐接近建筑物,建筑物差异沉降及扭曲变形逐渐增大;差异沉降量在盾构机通过时达到最大值,之后趋于稳定,而扭曲变形峰值出现在盾构开挖面到达建筑物中点截面位置时,随后逐渐减小;当建筑物中心至隧道轴线的水平距离与隧道外径之比L/D=0.5~2 时,建筑物差异沉降量较大,在L/D=1.5 时达到峰值;当盾构穿越夹角从θ=0°增大至θ=90°时,建筑物最大差异沉降量不断增加,而最终扭曲变形值则先增大后减小,在θ=45°时扭曲变形达到峰值。研究结果可为盾构隧道侧穿浅基础建筑物时相关类似工程提供参考。  相似文献   
366.
This paper introduces an integrated water management model at the industrial park level. It suggests four approaches to water management: first, direct water reuse among users; second, water reuse among users by blending with freshwater; third, water reuse between users and a wastewater treatment plant; and fourth, groundwater recharge by reclaimed wastewater or other feasible applications in order to optimize the overall water efficiency. The model results in a comprehensive management methodology for optimizing water resources within an industrial park, seeking potential water reuse among industries, and incorporating the size and cost of reclaimed wastewater delivery systems. A case study is employed to test the model’s feasibility. An economic analysis of the optimized water use network is also carried out, showing the potential water and cost savings.  相似文献   
367.
Effect of NOM characteristics on brominated organics formation by ozonation   总被引:5,自引:0,他引:5  
In this study, organic fractions, namely, humic acid, fulvic acid, hydrophobic base and neutral, and hydrophilic acid, base, and -neutral, were extracted from source water. First, the characteristics of the organic fractions, such as carboxylic acidity, phenolic acidity, ultraviolet absorbance, and aromatic content, were analyzed. Further, a systematic study was carried out to the by-products obtained when organic fractions, to which various amounts of bromide had been added, were oxidized with ozone. Samples after ozonation were analyzed for several brominated organics. The results indicate that the characteristics of the aquatic organic matter, including carboxylic/phenolic acidity, aromatic/aliphatic content, and ultraviolet absorbance, appear to affect the formation of halogenated organics. In general, hydrophobic organics having higher phenolic acidity, aromatic content, and ultraviolet absorbance have higher ozone consumption and produce higher concentrations of brominated organics than hydrophilic organics. It was also found that humic acid demonstrated the highest bromoform (CHBr(3)), dibromoacetic acid (DBAA), and 2,4-dibromophenol (2,4-DBP) formation, whereas hydrophilic neutral produced less CHBr(3) and 2,4-DBP than the rest of the organic fractions but produced the highest amount of dibromoacetone (DBAC) and dibromoacetonitrile (DBAN).  相似文献   
368.
This article measures the changes in energy use, blue water footprint, and greenhouse gas (GHG) emissions associated with shifting from current US food consumption patterns to three dietary scenarios, which are based, in part, on the 2010 USDA Dietary Guidelines (US Department of Agriculture and US Department of Health and Human Services in Dietary Guidelines for Americans, 2010, 7th edn, US Government Printing Office, Washington, 2010). Amidst the current overweight and obesity epidemic in the USA, the Dietary Guidelines provide food and beverage recommendations that are intended to help individuals achieve and maintain healthy weight. The three dietary scenarios we examine include (1) reducing Caloric intake levels to achieve “normal” weight without shifting food mix, (2) switching current food mix to USDA recommended food patterns, without reducing Caloric intake, and (3) reducing Caloric intake levels and shifting current food mix to USDA recommended food patterns, which support healthy weight. This study finds that shifting from the current US diet to dietary Scenario 1 decreases energy use, blue water footprint, and GHG emissions by around 9 %, while shifting to dietary Scenario 2 increases energy use by 43 %, blue water footprint by 16 %, and GHG emissions by 11 %. Shifting to dietary Scenario 3, which accounts for both reduced Caloric intake and a shift to the USDA recommended food mix, increases energy use by 38 %, blue water footprint by 10 %, and GHG emissions by 6 %. These perhaps counterintuitive results are primarily due to USDA recommendations for greater Caloric intake of fruits, vegetables, dairy, and fish/seafood, which have relatively high resource use and emissions per Calorie.  相似文献   
369.
Measures for vehicle exhaust emissions aimed at reducing either air pollution or global warming could have counterproductive effects on one another. Increasing diesel passenger vehicles, which generally have lower CO2 emissions than gasoline counterparts, leads to increasing particulate matter (PM) emissions, while gasoline has lower PM emissions than diesel. It is said that stringent limits on PM emission factors discourages improved CO2 emission factors. Without including both effects in a risk evaluation, one cannot evaluate whether the total risk is reduced or not. Hence, we evaluated representative exhaust emission measures based on risk evaluation for both air pollution and global warming. Considering consumer choice between diesel and gasoline passenger vehicles and emissions standards adopted in Japan from 1995 to 2005, we built five cases for vehicle policy evaluation. For each case, we estimated disability-adjusted life years (DALY) as an index of human health risk caused by lung cancer linked to inhalation exposure of elemental carbon in PM as well as due to global warming linked to CO2. The results of our risk evaluation reveal that the case adopting the 2005 new long-term Japanese emission standard reduces the human health risk caused by lung cancer due to air pollution by 0.6 × 103 DALY, but would increase the risk due to global warming by 31.9 × 103 DALY compared with the case of adopting EURO 4, for the same conditions of passenger vehicle choice from 1995. These results suggest that the characteristics of Japanese emissions standards are mainly designed to reduce air pollution.  相似文献   
370.
To achieve a safe and reliable drinking water supply, water producers need to manage a large range of risks regarding both water quality and quantity. A risk management approach where risks are systematically identified and handled in a preventive manner is promoted by the World Health Organization and supported by researchers and drinking water experts worldwide. Risk assessment is an important part of such a management approach, and a variety of tools for risk assessment are described in the literature. There is, however, little knowledge of how drinking water risk assessment is performed in practice, including which tools that are actually used. This study investigates the use of risk assessment tools, and the approach to risk management, on a local level in the Swedish water sector. It is based on interviews with key persons from a targeted selection of water producers. We find that the application of tools as well as the approach to risk assessment and management differs considerably between the water producers. The tools most frequently used are mainly the ones promoted or required by Swedish national organizations. Although many of the water producers have done some kind of risk assessment, most have not implemented a risk management approach. Furthermore, their knowledge of the concepts of risk and risk management is often limited. The largest challenge identified is to prioritize risk assessment, so that it is actually performed and then used as a basis for managing risk in a systematic way.  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