全文获取类型
收费全文 | 14754篇 |
免费 | 1264篇 |
国内免费 | 3597篇 |
专业分类
安全科学 | 1003篇 |
废物处理 | 304篇 |
环保管理 | 4074篇 |
综合类 | 9007篇 |
基础理论 | 1614篇 |
环境理论 | 1篇 |
污染及防治 | 1275篇 |
评价与监测 | 1250篇 |
社会与环境 | 838篇 |
灾害及防治 | 249篇 |
出版年
2024年 | 37篇 |
2023年 | 210篇 |
2022年 | 346篇 |
2021年 | 383篇 |
2020年 | 457篇 |
2019年 | 403篇 |
2018年 | 344篇 |
2017年 | 525篇 |
2016年 | 666篇 |
2015年 | 774篇 |
2014年 | 773篇 |
2013年 | 1105篇 |
2012年 | 1127篇 |
2011年 | 1204篇 |
2010年 | 841篇 |
2009年 | 848篇 |
2008年 | 657篇 |
2007年 | 1082篇 |
2006年 | 999篇 |
2005年 | 793篇 |
2004年 | 679篇 |
2003年 | 697篇 |
2002年 | 600篇 |
2001年 | 491篇 |
2000年 | 458篇 |
1999年 | 399篇 |
1998年 | 277篇 |
1997年 | 268篇 |
1996年 | 242篇 |
1995年 | 213篇 |
1994年 | 188篇 |
1993年 | 172篇 |
1992年 | 125篇 |
1991年 | 103篇 |
1990年 | 81篇 |
1989年 | 85篇 |
1988年 | 75篇 |
1987年 | 72篇 |
1986年 | 44篇 |
1984年 | 46篇 |
1983年 | 57篇 |
1982年 | 58篇 |
1981年 | 75篇 |
1980年 | 80篇 |
1979年 | 74篇 |
1978年 | 53篇 |
1977年 | 47篇 |
1973年 | 44篇 |
1972年 | 39篇 |
1971年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
991.
A. Camacho R. Devesa I. Serrano S. Blázquez L. Matia 《Journal of environmental radioactivity》2010,101(12):1048-1054
A study is presented on the distribution of 234U, 238U, 235U isotopes in surface water of the Llobregat river basin (Northeast Spain), from 2001 to 2006. Sixty-six superficial water samples were collected at 16 points distributed throughout the Llobregat river basin. Uranium isotopes were measured by alpha spectrometry (PIPS detectors). The test procedure was validated according to the quality requirements of the ISO17025 standard. The activity concentration for the total dissolved uranium ranges from 20 to 261 mBq L−1. The highest concentrations of uranium were detected in an area with formations of sedimentary rock, limestone and lignite. A high degree of radioactive disequilibrium was noted among the uranium isotopes. The 234U/238U activity ratio varied between 1.1 and 1.9 and the waters with the lowest uranium activity registered the highest level of 234U/238U activity ratio. Correlations between uranium activity in the tested water and chemical and physical characteristics of the aquifer were found. 相似文献
992.
Alebel Abebe Belay Henry Musoke Semakula George James Wambura Labohy Jan 《中国人口.资源与环境(英文版)》2010,8(1):8-17
River Nile is one of the longest transboundery rivers and it is shared and used by Burundi,Democratic Republic of Congo,Egypt,Ethiopia,Eritrea,Kenya,Rwanda,Sudan,Tanzania and Uganda.As of today,the Nile is a crucial resource for the economic development of the Nile Basin countries and a vital source of livelihood for 160 million inhabitants as well as 300 million people living in the 10 riparian countries.The Nile Basin Initiative(NBI) is one of the international cooperative river basin management program and regional partnership where all the Nile Basin countries except Eritrea unite to pursue long-term sustainable development,improved land use practices and management.This review therefore focused on the challenges not faced on NBI in terms of integrated use of the river and conducted analysis of strengths,weaknesses,opportunities and threats(SWOT) based on secondary data.The result of the review revealed that for decades,the Nile Basin people have been facing many complex environmental,social,economic and political challenges that have made it difficult for the proper management and sustainability of Nile water.The initiative provides training to develop skills in government ministries,non-governmental organizations and local communities in each country.It is also working to raise awareness of critical environmental issues by strengthening networks of environmental education practitioners;developing curriculum in the education sector.The challenges of NBI include the involvement and funding of World Bank,lack of sufficient staff,procedural and policies conflicts,lack of coordination and linkage with other regional institutions and lack of recognition as river basin organization.Considering the complex nature of the project,it is recommended that the NBI should come up with a strong multi-disciplinary monitoring and evaluation team to follow up all implemented projects.The NBI should carry out participatory land use planning in communities along the river basin.Moreover,livelihood analysis should be carried out especially in communities along the Nile to come up with poverty eradication projects which are socially acceptable,applicable,economically viable and affordable. 相似文献
993.
超高效液相色谱-质谱法测定地表水中丁基黄原酸 总被引:1,自引:1,他引:0
建立了直接测定水中丁基黄原酸的超高效液相色谱-电喷雾串联四极杆质谱法,无需对水样进行富集,水样过滤后就可直接测定。该方法简单、快捷、灵敏度高,方法检出限可达0.2μg/L。 相似文献
994.
固相萃取—气相色谱—质谱测定再生水中邻苯二甲酸酯类物质 总被引:2,自引:0,他引:2
探讨了一种再生水中邻苯二甲酸酯类物质的测定方法——固相萃取—气相色谱—质谱,检测了相关再生水标准中涉及的邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)两类物质。在质量浓度为20~1 000μg/L时,两类物质的回归方程的相关系数均大于0.999,检出限分别是0.060、0.002μg/L,DBP、DEHP的相对标准偏差分别为4.1%~7.4%、5.1%~6.1%。利用固相萃取技术进行预处理,平均加标回收率为96.6%、89.6%。检测了北京市4座再生水厂出水中DBP和DEHP含量,其中,DBP在1.74~5.59μg/L,低于《城市污水再生利用景观环境用水水质》(GB/T 18921—2002)规定的限值(不超过0.1mg/L),但高于《城市污水再生利用地下水回灌水质》(GB/T 19772—2005)规定的限值(不超过3μg/L);DEHP在0.42~4.93μg/L,满足GB/T 19772—2005要求(不超过8μg/L)。 相似文献
995.
混凝-Fenton试剂氧化工艺处理机械厂洗涤废水 总被引:2,自引:0,他引:2
对某厂机械洗涤废水,采用混凝-Fenton试剂进行处理。结果表明,用聚铝(w(PAC)=5%)对废水进行絮凝沉淀,PAC最佳投加量为1.5 mL/L(废水),絮凝后的COD去除率为29.6%;芬顿试剂最佳操作条件为:n(H2O2)∶n(Fe2+)=5∶1,m(H2O2)∶m(COD)=2.5∶1,废水pH=5,温度为30℃,反应时间为2 h,经氧化后,COD的去除率为78.5%;经过混凝沉淀-芬顿氧化处理,COD的总去除率为84.9%,去除效果良好。 相似文献
996.
Lauren A. Patterson Jeffrey Hughes Glenn Barnes Stacey I. Berahzer 《Journal of the American Water Resources Association》2012,48(4):838-848
Patterson, Lauren A., Jeffrey Hughes, Glenn Barnes, and Stacey I. Berahzer, 2012. A Question of Boundaries: The Importance of “Revenuesheds” for Watershed Protection. Journal of the American Water Resources Association (JAWRA) 48(4): 838‐848. DOI: 10.1111/j.1752‐1688.2012.00655.x Abstract: Watersheds transcend jurisdictional boundaries; raising important questions of who should pay for watershed protection, and how can watershed governance be funded? The responsibility and cost for watershed protection has progressively devolved to local governments, resulting in additional negative externalities and financing challenges. Watershed governance structures have formed at the scale of the watershed, but they often lack the financing mechanisms needed to achieve policy goals. Financing mechanisms via local governments provide a reliable source of revenue and the flexibility to address watershed specific issues. We develop a “revenueshed” approach to access the initial challenges local governments face when seeking to finance trans‐jurisdictional watershed governance. The revenueshed approach engages local governments into discussion and implementation of financial strategies for collaborative watershed governance. Legislation places water quality regulations primarily on local governments inside the watershed. The revenueshed approach extends the financial and stewardship discussion to include local governments outside the watershed that benefit from the watershed. We applied the revenueshed approach to the Mills River and Upper Neuse watersheds in North Carolina. Mills River had a partnership governance seeking revenue for specific projects, whereas the Upper Neuse sought long‐term financial stability to meet new water quality legislation. 相似文献
997.
998.
饮用水安全是最大的民生工程,也是自然资源管理研究的热点。基于实地调研、部门访谈和制度条文的梳理与分析,以苏州市太湖水源地为例研究湖泊型水源地管理体制。研究表明:我国水源地管理由国家、省、市、县的法律法规、规章和规范性文件构成相对完善的制度体系,具有水资源和水环境分割管理、流域管理和行政区管理交错的制度特征,初步具备了综合管理的架构;水源保护缺乏流域管治的思维,农村面源污染治理制度支撑不足;在管理手段上以命令控制型手段为主,经济激励与公众参与不足。建立水源地综合管理协调机制,完善经济激励手段,推进公众参与,实施水源地管理共同责任机制将有利于提高水源地管理效率 相似文献
999.
浊漳河山西省潞城市境内干流段及南源段河道生态环境目前最突出的问题在于水质恶化、水量减少以及生物多样性衰退。本文从水质、水量、生物状况三个要素出发,通过建立浊漳河潞城市境内河段的水生态健康评价体系,对浊漳南源及干流段进行了生态健康诊断。结果显示,浊漳干流段生态健康总指数36.74,呈生态病态状;南源段生态健康总指数60.03,呈基本健康状态。据此,浊漳河潞城境内段目前的核心问题是生态恢复问题,应当针对其存在的问题选择适当的生态修复模式,采取相应的生态环境管理方法,把生态系统的恢复和重建作为其流域治理的最终目标。 相似文献
1000.
2008年江苏持续性降雪中的水汽和动力抬升机制分析 总被引:1,自引:0,他引:1
2008年1月下旬江苏省出现了历史罕见的持续性暴雪过程,研究发现,降雪量的大小与低空急流的日变化相对应,暴雪过程中700 hPa西南急流对水汽的输送起着重要的作用,作为大尺度天气系统,700 hPa急流的加速发生在降雪量增大之前,其值阈大小与6 h降雪量之间没有对应关系,急流减弱在暴雪结束以后;降雪的发生和发展与南北风的增大和冷暖平流有关,低层偏北风作为冷垫对暖湿气流的抬升和水汽的凝结起到了一定的作用;江苏降雪过程中水汽主要来源于700~500 hPa,低层东风气流对黄海南部的水汽输送非常有限;强降雪的发生与700 hPa水汽通量散度相对应,水汽通量散度辐合增大,降雪量增大;在降雪过程中垂直运动对降雪量的大小有很好的指示意义。 相似文献