全文获取类型
收费全文 | 803篇 |
免费 | 4篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 19篇 |
废物处理 | 12篇 |
环保管理 | 222篇 |
综合类 | 300篇 |
基础理论 | 113篇 |
污染及防治 | 107篇 |
评价与监测 | 39篇 |
社会与环境 | 28篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 33篇 |
2013年 | 38篇 |
2012年 | 26篇 |
2011年 | 50篇 |
2010年 | 27篇 |
2009年 | 50篇 |
2008年 | 54篇 |
2007年 | 42篇 |
2006年 | 39篇 |
2005年 | 26篇 |
2004年 | 32篇 |
2003年 | 33篇 |
2002年 | 32篇 |
2001年 | 29篇 |
2000年 | 36篇 |
1999年 | 22篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有843条查询结果,搜索用时 31 毫秒
811.
812.
813.
814.
冬春季富营养化滆湖中沉水植被重建及净化效果 总被引:1,自引:0,他引:1
秋末冬初在富营养化滆湖的围隔中引种沉水植物,分别构建5种植被区、菹草-伊乐藻区、菹草区、伊乐藻区,调查4种区域内植被恢复及对水质的净化效果。结果发现菹草-伊乐藻区不仅能在冬春季节保持对营养盐较高的去除效果,并能在冬季有效缓解苦草等植物死亡(5种植被区)给水质带来的不利影响;菹草-伊乐藻区对比湖面敞开区域内TP,TN,NH3-N,Chl.a的去除率可达62.9%,31.5%,53.9%,46.1%,对CODMn的去除率仅为9.7%;比较各单种区:伊乐藻对TN的去除效果要好于菹草,菹草对TP的去除效果要好于伊乐藻。 相似文献
815.
Wei Wu Ji-long Chen Hong-bin Liu Axel Garcia y Garcia Gerrit Hoogenboom 《Agriculture, ecosystems & environment》2010,135(1-2):111-118
Soil and weather data are critical for the operation of crop simulation models. However, in many cases they are not readily available, especially applications at a regional or larger spatial scale. The Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) provides massive quantities of geo-referenced soil and weather data variables on a half-degree latitude–longitude grid covering the conterminous USA. The VEMAP data were derived from a range of products and analyses, including ground observations, cluster analyses, kriging interpolation, and data assimilation. The objective of this study was to convert the soil and daily weather data of VEMAP into a format that can be used in the popular modeling software Decision Support System for Agrotechnology Transfer (DSSAT). Users can select appropriate soil or daily weather information for the area of interest. The conversion of the VEMAP data resulted in 5927 unique soil profiles and 3261 unique weather station files that encompass daily data from 1895 to 1993. To demonstrate the utility of this database in DSSAT, one representative county of the state of Georgia, USA was selected and a soybean simulation model was employed to simulate final yield using the extracted soil and daily weather data for the normal year (1961–1990). Meanwhile, the extracted daily weather data were compared with ground station observations from the National Weather Service Cooperative Observer Program (COOP). The paired t-test showed that no significant differences were found between the daily weather data and between simulated yields based on VEMAP and COOP weather data for the selected location. The outcome of this research showed that the VEMAP data can be used for crop model applications. However, further research is needed to assess the accuracy of the datasets for a variety of crops at a regional or national scale. 相似文献
816.
Reducing fertiliser applications can reduce production costs for cotton (Gossypium hirsutum L.) growers, as well as nitrogen (N) leaching into the soil and contamination of surface and ground water. But altered N fertilisation may also affect pests and their natural enemies. In this study, plots with four different levels of fertiliser input (0, 45, 90 and 135 kg ha−1 N) were used to investigate the influence of N on cotton pest and beneficial arthropod populations, and on cotton yield in Tifton, GA, USA. We predicted that (1) N fertilisation will correlate positively with cotton plant growth; (2) increased N fertilisation will increase pest populations because plants with more N will be more nutritious for and attractive to herbivores; (3) populations of beneficial arthropods and predation of pests will decline with increased N fertilisation because of reduced plant signaling; (4) increased N fertilisation will increase pest mortality due to parasitoids because of increased host quality. Cotton plant growth was enhanced by N fertilisation but yield was unaffected. N fertilisation significantly affected some pest arthropods but inconsistently. Mirids were most abundant in the high N treatment in 1 year of the study and cotton aphids were most abundant in the highest N treatment in the other year of the study. Arthropod predators were generally more abundant in the high N treatment but only spiders and Geocoris spp. were significantly affected by N treatment, with highest numbers present in the highest N treatment but the significant differences were each only in a single year. The greatest mortality of sentinel pest eggs (Spodoptera exigua) due to predation occurred under low N conditions. N fertilisation had no significant effects on parasitism of feral or sentinel caterpillars. 相似文献
817.
Jin Sato 《Sustainability Science》2007,2(2):151-158
The objective of this paper is to trace the evolution of the resource concept in modern Japan by highlighting key individuals
who played major roles in communicating this idea to a wider audience during its formation and development between the 1910s
and 1950s. Special attention will be paid to the effect of different historical contexts on interpretations of the term “resource”.
The paper reveals how the integration of knowledge indispensable for achieving sustainability occurs. The orientation of resource
policy was drastically different before and after World War II. In the pre-war period, the military government used the resource
concept to create a comprehensive inventory of the nation’s military forces, and “resource” was thus a convenient term to
neutralize the aggressive connotations of top-down military mobilization. After the turn to democratic principles in 1945,
“resource” suddenly acquired a symbolic meaning as a means to serve the people. Despite these contrasts, however, pre and
post-war resource concepts share a commonality in that the government acted as the centralizing force, providing a platform
to integrate disparate knowledge under the resource concept. At a time when society itself is more prone to fragmentation,
the resource concept, which played a significant role in unification in the past, should be re-examined. The history of the
concept in Japan, particularly during the pre and post-war period up until the 1950s, contains a wealth of insights as to
how this can be achieved.
相似文献
Jin SatoEmail: |
818.
依兰航电枢纽的建设,不仅改善了当地乃至松花江流域的航运条件、旅游环境,而且促进了松花江航道及区域经济可持续发展.同时,项目的建设也产生了一些环境问题.施工期作业区水文条件的改变对水生生物及渔业资源造成了影响.营运期库区水域生态环境的改变,使得浮游生物和底栖生物种类发生变化,鱼类组成将由复杂变为简单.因此,本文提出适宜的... 相似文献
819.
820.
Impacts of atrazine in aquatic ecosystems 总被引:26,自引:0,他引:26
A portion of all herbicides applied to forests, croplands, road sides, and gardens are inevitably lost to water bodies either directly through runoff or indirectly by leaching through groundwater into ephemeral streams and lakes. Once in the aquatic environment, herbicides may cause stress within aquatic communities and radically alter community structure. Atrazine is one of the most effective and inexpensive herbicides in the world and is consequently used more frequently than any other herbicide. Atrazine is frequently detected in aquatic waters, and has been known to affect reproduction of aquatic flora and fauna, which in turn impacts on the community structure as a whole. This paper presents a summary of the reported direct and indirect impacts of atrazine on aquatic organisms and community structure. The information can be used for developing improved management guidelines and legislation. It is concluded that a single universal maximum limit on the atrazine application in catchments, as suggested by many regulatory authorities, does not provide adequate protection of the aquatic environment. Rather, it is advocated that flexible limits on the application of atrazine be developed in line with the potential risk of contamination to surface and subsurface water and fragility of the aquatic environment. 相似文献