全文获取类型
收费全文 | 6439篇 |
免费 | 456篇 |
国内免费 | 1001篇 |
专业分类
安全科学 | 366篇 |
废物处理 | 69篇 |
环保管理 | 1806篇 |
综合类 | 3201篇 |
基础理论 | 613篇 |
污染及防治 | 336篇 |
评价与监测 | 1230篇 |
社会与环境 | 229篇 |
灾害及防治 | 46篇 |
出版年
2024年 | 39篇 |
2023年 | 121篇 |
2022年 | 159篇 |
2021年 | 184篇 |
2020年 | 193篇 |
2019年 | 145篇 |
2018年 | 138篇 |
2017年 | 215篇 |
2016年 | 255篇 |
2015年 | 275篇 |
2014年 | 324篇 |
2013年 | 407篇 |
2012年 | 430篇 |
2011年 | 464篇 |
2010年 | 318篇 |
2009年 | 339篇 |
2008年 | 284篇 |
2007年 | 429篇 |
2006年 | 395篇 |
2005年 | 303篇 |
2004年 | 264篇 |
2003年 | 275篇 |
2002年 | 254篇 |
2001年 | 197篇 |
2000年 | 195篇 |
1999年 | 157篇 |
1998年 | 123篇 |
1997年 | 117篇 |
1996年 | 122篇 |
1995年 | 95篇 |
1994年 | 84篇 |
1993年 | 58篇 |
1992年 | 47篇 |
1991年 | 56篇 |
1990年 | 25篇 |
1989年 | 30篇 |
1988年 | 36篇 |
1987年 | 30篇 |
1986年 | 24篇 |
1985年 | 19篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 27篇 |
1981年 | 27篇 |
1980年 | 31篇 |
1979年 | 28篇 |
1978年 | 18篇 |
1977年 | 15篇 |
1975年 | 15篇 |
1973年 | 18篇 |
排序方式: 共有7896条查询结果,搜索用时 656 毫秒
811.
An 11-year period of water quality data, collected by the Directorate of Sate Water Works of Turkey are thoroughly analyzed
for the purpose of implementing water quality classes to water resources in the Meric Basin, located on the European land
mass of Turkey. Water quality parameters are divided into four groups as physical, organic, inorganic, and bacteriological.
The quality class of each group is evaluated by taking into account the poorest quality of any parameter in the group, after
which a quality rank is assigned to the sampling station and the waterbody in question. This method of water quality classification
imposed by the Turkish Water Quality Act, is then criticized with respect to a statistical approach. 相似文献
812.
William E. Sharpe 《Journal of the American Water Resources Association》1975,11(3):546-550
ABSTRACT: Recent watershed research indicates that many timber management practices have profound effects on the water quality of small headwater streams. These streams often support fisheries of high value. Current knowledge seems to indicate that a definite potential exists for a symbiotic relationship between timber and fisheries management. Maximum development of both resources is attainable only if further research efforts recognize the mutually benefiting aspects of these heretofore separate disciplines. Future research should carefully examine the complex interrelationships between small headwater aquatic ecosystems and the riparian forest environment. 相似文献
813.
Ashok K. Alva 《Environmental management》1992,16(6):769-776
Extremely sandy soils and poorly distributed high annual rainfall in the state of Florida contribute to significant leaching
losses of nutrients from routine fertilization practices. A leaching column experiment was conducted to evaluate the leaching
losses of nutrients when using currently available N, P, K blend fertilizers for young citrus tree fertilization. Fertilizer
blends included NH4NO3, Ca(NO3)2, IBDU, IBDU plus Escote, Nutralene, Osmocote, and Meister. Following leaching of 1000 ml of water through soil columns, which
simulates leaching conditions with 26 cm of rainfall, the amount of NO3 and NH4 recovered in the leachate from soil columns amended with an NH4NO3 blend accounted for 37% and 88% of the respective nutrients contained in the quantity of blend per column. The corresponding
values for soil columns amended with a Ca(NO3)2 blend were 48% and 100%. Leraching losses of both NO3 (<3%) and NH4 (<4%) were drastically decreased when using controlled-release fertilizers. The recoveries of P and K in 1000 ml of leachate
were 1.3% and 8%, respectively, of the nutrients added as Osmocote, which contained coated P and K sources. In the case of
the rest of fertilizer blends, the recoveries of P and K in 1000 ml of leachate were as high as 52%–100% and 28%–100%, respectively.
Therefore, controlled-release technology offers an important capability for minimizing leaching losses of nutrients. 相似文献
814.
县域耕地总量动态平衡规划模式的构建--以江苏省启东市为例 总被引:2,自引:0,他引:2
本文在界定耕地总量动态平衡是由耕地数量、耕地质量和耕地生态环境三者组成的整体平衡的基础之上 ,对耕地总量的评价方法进行了初步研究 ,并以启东市为例 ,构建了耕地生产力总量动态平衡规划模式。 相似文献
815.
The aim of this study is to analyze the environmental agenda in Sweden during the last two decades. A content analysis was made of all articles in a Swedish journal,Miljö-Aktuellt. Further, to elucidate the evolutionary process of problem formulation and reformulation, two cases were investigated, dealing with the impact of plant nutrients and mercury on surface water quality. The transport of heavy metals is an essential component of the ecological process and problem of acidification, and similarly, plant nutrients are part of the concept of eutrophication. Two concepts, the research cycle and the policy cycle, are tentatively applied to the conceptualizations of acidification and eutrophication. Additional data for the latter part of the study is supplied from parliamentary motions during 1973–1989. The substance/media focus of the 1970s was connected to a point-source abatement strategy, which mainly aimed at removing negative effects at a local level. The development of a national preventive strategy is traced in problem formulations related to “processes” going on in the technosphere: wastes, noise, energy production, traffic, and toxic substances. This period lasted from the mid-1970s to the mid-1980s, and the need for improved resource management as a means to control environmental problems has been a generally accepted idea. However, this does not mean that measures actually taken are sufficient in a material balance perspective. Further, in the 1980s there was a strong emphasis upon processes in the ecosphere. This focus also implies source-related policies. To a certain extent, the remedies are within the scope of national capabilities, but the international dimension is becoming increasingly important. Scientific proofs of resource and environment degradation are essential to induce political action and to stimulate international cooperation. From this study, however, it is not possible to assess the existence of any particular policy-triggering information. 相似文献
816.
黄伟雄 《中国人口.资源与环境》2002,(5)
本文从资源、环境和人地关系的角度探讨我国的可持续发展问题 ,分析了影响我国可持续发展因素 ,指出中华民族的人口素质是我国可持续发展的关键 ,阐明科教兴国是我国可持续发展的必由之路 相似文献
817.
Marek Makowski Lszl Somlydy David Watkins 《Journal of the American Water Resources Association》1996,32(5):937-951
ABSTRACT: This paper presents the implementation of one element of a decision support system (DSS) for regional water quality management, applied to the Nitra River Basin in Slovakia. A model-based, aspiration-led methodology for multicriteria decision support has been used for the study. Several reusable, modular software tools have been developed and implemented: a problem-specific generator to produce the core part of the mathematical programming model, tools for the generation and interactive modification of multicriteria problems, and a solver for the resulting mixed-integer optimization problem. Provided in the paper are the following: a complete formulation of the mathematical model (including the imbedded water quality model), a summary of the aspiration-reservation-led multiple criteria optimization approach applied to decision support, and an overview of results that illustrate the applied approach and provide some interesting insights to the case study. 相似文献
818.
Marco Keiner 《Environment, Development and Sustainability》2005,6(4):379-392
The principle of sustainable development is now 15-year-old. There are a lot of definitions and models for its explanation — ranging from triangles and prisms to eggs — but still its sense is diffuse. Moreover, important aspects like equity are not sufficiently taken into account.The following article takes a critical look on sustainable development. It shows logical, systemic, philosophic and ethic reasons for the re-development of substantial parts of the principle of sustainability. Based on the proposed Principle of Good Heritage it provides a rough outline of a future Concept of Evolutionability, comprising a first tentative for a definition of evolutionable development, aiming at achieving a more appropriate and more workable mainstream view of sustainability.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
819.
试论改善发展的质量 总被引:2,自引:0,他引:2
毛文永 《中国人口.资源与环境》1995,5(2):23-26
本文结合中国国情,从经济发展的目标、边界、途径等方面论述了改善发展质量的基本内涵,提出经济发展应以满足社会基本需要为目标,经济发展必须与环境和资源的承载力相适应,依靠科技进步是提高发展质量的根本途径,同时须不断改善经济的内部结构,走资源节。 相似文献
820.
区域生态环境评价的灰色关联投影模型 总被引:11,自引:0,他引:11
区域生态环境评价是实现全面环境管理,协调区域经济发展与生态环境保护.实现区域可持续发展的重要手段。由于评价所涉及的地域复杂性和因素多样性,许多评价方法和体系都处于不断探索和发展之中。区域生态环境系统是一个灰色系统,包括了自然、经济和社会等方面具有信息不确知性和不完全性的因素。基于灰色系统理论和矢量投影原理,建立了区域生态环境评价的灰色关联投影模型。该模型将评价样本及各级质量标准视为矢量.分别向同一矢量(理想样本)进行投影。根据投影值的大小,确定样本所属的生态环境质量级别及样本间的优劣排序。以巢湖流域为个案,在建立生态环境评价指标体系和标准的基础上,运用所建模型对其生态环境质量现状进行了评价,结果与实际情况相吻合。即巢湖流域总体以及分区合肥市、六安市的生态环境质量为4级,分区巢湖市为5级。研究表明,灰色关联投影模型对于多指标的区域生态环境质量评价是科学的、有效的,具有一定的推广和实用价值。 相似文献