全文获取类型
收费全文 | 6209篇 |
免费 | 575篇 |
国内免费 | 702篇 |
专业分类
安全科学 | 1322篇 |
废物处理 | 316篇 |
环保管理 | 1232篇 |
综合类 | 3086篇 |
基础理论 | 390篇 |
环境理论 | 4篇 |
污染及防治 | 353篇 |
评价与监测 | 359篇 |
社会与环境 | 188篇 |
灾害及防治 | 236篇 |
出版年
2024年 | 17篇 |
2023年 | 70篇 |
2022年 | 123篇 |
2021年 | 191篇 |
2020年 | 250篇 |
2019年 | 174篇 |
2018年 | 121篇 |
2017年 | 244篇 |
2016年 | 227篇 |
2015年 | 292篇 |
2014年 | 303篇 |
2013年 | 340篇 |
2012年 | 443篇 |
2011年 | 516篇 |
2010年 | 383篇 |
2009年 | 338篇 |
2008年 | 240篇 |
2007年 | 389篇 |
2006年 | 429篇 |
2005年 | 299篇 |
2004年 | 279篇 |
2003年 | 283篇 |
2002年 | 230篇 |
2001年 | 191篇 |
2000年 | 172篇 |
1999年 | 172篇 |
1998年 | 123篇 |
1997年 | 94篇 |
1996年 | 86篇 |
1995年 | 80篇 |
1994年 | 61篇 |
1993年 | 55篇 |
1992年 | 41篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1971年 | 12篇 |
排序方式: 共有7486条查询结果,搜索用时 203 毫秒
561.
Citizen science networks in natural history and the collective validation of biodiversity data 下载免费PDF全文
Biodiversity data are in increasing demand to inform policy and management. A substantial portion of these data is generated in citizen science networks. To ensure the quality of biodiversity data, standards and criteria for validation have been put in place. We used interviews and document analysis from the United Kingdom and The Netherlands to examine how data validation serves as a point of connection between the diverse people and practices in natural history citizen science networks. We found that rather than a unidirectional imposition of standards, validation was performed collectively. Specifically, it was enacted in ongoing circulations of biodiversity records between recorders and validators as they jointly negotiated the biodiversity that was observed and the validity of the records. These collective validation practices contributed to the citizen science character or natural history networks and tied these networks together. However, when biodiversity records were included in biodiversity‐information initiatives on different policy levels and scales, the circulation of records diminished. These initiatives took on a more extractive mode of data use. Validation ceased to be collective with important consequences for the natural history networks involved and citizen science more generally. 相似文献
562.
电解法处理含镍废水及纯镍的回收 总被引:1,自引:0,他引:1
雷英春 《城市环境与城市生态》2009,(3)
采用电解回收法处理Ni2+含量为2g/L的废水,在阴极回收纯镍。研究了电解电流、极距、NH4Cl浓度、pH值等因素对Ni2+去除率、槽压、阴极能耗的影响,得出最优工艺参数为:温度20℃,电解时间20min时、电解电流300mA,极距15mm,NH4Cl浓度5g/L,pH值8.0,该条件下Ni2+去除率为96.926%,槽压16.21V,阴极能耗22.418kW.h/kg,在阴极可得到沉积6.45μm厚的镍板。 相似文献
563.
环境保护同经济建设和社会发展相协调,是我国环境保护的基本原则。本文从环境保护与经济发展的相互关系出发,比较实际地估计了我省各种污染排放物及造成的经济损失,探讨了环保治理资金社会投入的比例问题。 相似文献
564.
石油工业废弃物处置及其生物治理趋势 总被引:4,自引:0,他引:4
鉴于我国石油工作者对石油工业废弃物的普遍关注,现在介绍生物治理的基本概念及SPE石油工程师协会中有关含油污泥生物处置的途径及其突出优越性。生物液/固处理工艺(LST)是目前含油污泥处置现场最经济可行的处置方案。这种好氧的LST工艺过程,能够比较充分地代谢和降解石油污泥中的油和脂并大量除去多环芳烃类(PAH)化合物及其它有机化合物,明显地降低了石油废弃物对人、畜的毒害程度。其工艺较简单,操作也简易,凡经此工艺处理后的废弃物不留残毒和后患,因此早已被世界上先进国家的炼油业视为处理含油污泥的有效选择了。石油工业废弃物的生物防治和生物降解工艺较大程度地领先于目前我国现场正在执行的各种处理含油废弃物的处理工艺。 相似文献
565.
对钻井废物污染的全过程控制 总被引:4,自引:1,他引:4
在钻井作业过程中控制废物的排放量和毒性,变末端处理为全过程控制,采取各种措施预防钻井废物的污染是近年来国外油气田环保工作的一项重要内容。本文就采用小井眼钻井工艺;减少井眼冲蚀;强化环境管理;提高钻井液固控系统的处理效率;开发各种合成基钻井液;采用低毒无害的钻井液化学添加剂等6个方面讨论了减少钻井废物产生量的途径和降低钻井液及添加剂对环境的影响 相似文献
566.
本文根据调查分析,指出建设城市防火安全系统的迫切性。阐述了建设城市防火安全系统的基本原理和规划方法。并探讨了城市防火安全系统的运用管理。 相似文献
567.
M. G. Lloyd 《Journal of Environmental Planning and Management》1985,28(1):46-49
A central government Consultation Paper issued in 1984 argues the case for simplified planning zones. These are seen to offer greater speed and certainty to developers and are closely related to the Enterprise Zone concept. This paper examines the context to the proposal, reviews the details of the Consultation Paper, and identifies the nature of the response to the idea. 相似文献
568.
Levees and floodwalls are used extensively throughout the United States for flood control. Levee projects often lack ecological, recreational, and aesthetic values, except for incidental fish and wildlife benefits derived from borrow pits and recreational facilities found in some urban settings. In recent years increased environmental concern within construction agencies and greater responsiveness to public opinion have resulted in increasing numbers of levee projects designed, built, and maintained with environmental objectives in mind. This paper reviews environmental concepts successfully employed on levee projects constructed in recent years by the US Army Corps of Engineers. Some of the most innovative concepts are described and illustrated and design considerations are discussed. 相似文献
569.
Rochelle L. Rittmaster David K. Mueller 《Journal of the American Water Resources Association》1986,22(1):81-89
ABSTRACT: A study was performed to identify sources of solute loading to the Dirty Devil River and its major tributaries, in southeastern Utah. A primary goal was to determine the contribution of gypsum dissolution to total dissolved solids concentration, and its potential increase in the future if salinity control measures are instituted. Synoptic field data were collected during the low flow period in October 1983. Data were analyzed using the geochemistry models WATEQF and BALANCE to postulate mineral reactions leading to solute loading. Three known sources of solute loading, involving two different geochemical mechanisms, were clearly discernable. Two additional areas of possible gypsum dissolution were located. 相似文献
570.
Bruce P. Van Haveren 《Journal of the American Water Resources Association》1986,22(3):399-404
ABSTRACT: The use of reservoirs and land treatments to manage streamflow for the maintenance or enhancement of instream flow values is a valid concept. Historically, large reservoirs have been used for flood control and water-supply regulation. Smaller structures have enjoyed widespread use for soil and water conservation in headwater areas. Where reservoir releases can be controlled, it is technically feasible to regulate flows for the enhancement of instream values. However, institutional and political obstacles may preclude the operation of some reservoirs for this purpose. Retention and detention structures and land treatments, implemented for soil and water conservation purposes, have often had favorable effects on the streamflow hydrograph. Decreases in peak flows and increases in low flows have been documented. Design concepts for runoff-control structures are discussed in relation to instream flow management objectives. Hydro-logic simulation is offered as a potential tool for project design and feasibility analysis. 相似文献