全文获取类型
收费全文 | 1930篇 |
免费 | 84篇 |
国内免费 | 218篇 |
专业分类
安全科学 | 196篇 |
废物处理 | 117篇 |
环保管理 | 933篇 |
综合类 | 597篇 |
基础理论 | 125篇 |
污染及防治 | 99篇 |
评价与监测 | 94篇 |
社会与环境 | 22篇 |
灾害及防治 | 49篇 |
出版年
2024年 | 3篇 |
2023年 | 22篇 |
2022年 | 24篇 |
2021年 | 27篇 |
2020年 | 35篇 |
2019年 | 22篇 |
2018年 | 14篇 |
2017年 | 26篇 |
2016年 | 30篇 |
2015年 | 30篇 |
2014年 | 41篇 |
2013年 | 52篇 |
2012年 | 45篇 |
2011年 | 59篇 |
2010年 | 50篇 |
2009年 | 50篇 |
2008年 | 67篇 |
2007年 | 52篇 |
2006年 | 47篇 |
2005年 | 30篇 |
2004年 | 60篇 |
2003年 | 91篇 |
2002年 | 179篇 |
2001年 | 164篇 |
2000年 | 177篇 |
1999年 | 146篇 |
1998年 | 110篇 |
1997年 | 85篇 |
1996年 | 219篇 |
1995年 | 64篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 22篇 |
1984年 | 38篇 |
1983年 | 35篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 10篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 14篇 |
1967年 | 1篇 |
排序方式: 共有2232条查询结果,搜索用时 0 毫秒
1.
Cornus stolonifera, Salix petiolaris, and Spiraea alba
clones already located within the corridor of an electrical power line. To
establish the efficiency of treatments, we examined the statistical
differences of growth traits between species and treatments.
An analysis of the effects of layering shows, after the first growth season,
differences for all growth traits in only one species, Spiraea alba.
After the second growth season, we observed the development of new aerial
stems. Layering favors horizontal expansion of shrubs over height
development. The third year after treatment, the effect of layering is
reduced except for Cornus stolonifera, which continuously increases,
as shown by the significant progression of the clone issued from the layer
even five years after treatments. With the cutting back technique, we
expected a distinct vertical growth of the shrubs at the expense of
increasing the crown diameter. This technique would be best associated with
the rejuvenation of clones, followed by a layering of new shoots to allow a
horizontal expansion of the shrubs. Therefore, the formation of a dense shrub
community by layering should be considered a valuable approach for the
biological control of undesirable trees in powerline rights-of-way. 相似文献
2.
María L. Pignata Martha S. Cañas Hebe A. Carreras Liliana Orellana 《Environmental management》1997,21(5):793-801
Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd. in relation to atmospheric pollutants in Córdoba city, Argentina. The study area receives
regional pollutants and was categorized taking into account traffic level, industrial density, type of industry, location
of the sample point in relation to the street corner, treeless condition, and topographic level. Dried weight/fresh weight
ratio (DW/FW) and specific leaf area (SLA) were calculated, and concentrations of chlorophylls, carotenoids, total sulfur,
soluble proteins, malondialdehyde (MDA), and hydroperoxy conjugated dienes (HPCD) were determined in leaf samples. Sulfur
content correlates positively with traffic density and SLA correlates negatively with some combinations of the categorical
variables; MDA correlates positively with topographic level and total protein concentration correlates negatively with treeless
condition. On the basis of our results, traffic, location of trees, type of industry, situation of a tree with respect to
others, and topographic level are the environmental variables to bear in mind when selecting analogous sampling points in
a passive monitoring program. An approximation to predict tree injury may be obtained by measuring DW/FW ratio, proteins,
pigments, HPCD, and MDA as they are responsible for the major variability of data. 相似文献
3.
Dynamics and Causation of Environmental Equity, Locally Unwanted Land Uses, and Neighborhood Changes
Feng Liu 《Environmental management》1997,21(5):643-656
/ Why are some environmental risks distributed disproportionately in the neighborhoods of the minorities and the poor? A hypothesis was proposed in a recent study that market dynamics contributed to the current environmental inequity. That is, locally unwanted land uses (LULUs) make the host communities home to more poor people and people of color. This hypothesis was allegedly supported by a Houston case study, whereby its author analyzed the postsiting changes of the socioeconomic characteristics of the neighborhoods surrounding solid waste facilities. I argue that such an analysis of postsiting changes alone is insufficient to test the causation hypothesis. Instead, I propose a conceptual framework for analysis of environmental equity dynamics and causation. I suggest that the presiting neighborhood dynamics and the characteristics of control neighborhoods be analyzed as the first test for the causation hypothesis. Furthermore, I present theories of neighborhood change and then examine alternative hypotheses that these theories offer for explaining neighborhood changes and for the roles of LULUs in neighborhood changes. These alternative hypotheses should be examined when analyzing the relationship between LULUs and neighborhood changes in a metropolitan area. Using this framework of analysis, I revisited the Houston case. First, I found no evidence that provided support for the hypothesis that the presence of LULUs made the neighborhoods home to more blacks and poor people, contrary to the conclusion made by the previous study. Second, I examined alternative hypotheses for explaining neighborhood changes-invasion-succession, other push forces, and neighborhood life-cycle; the former two might offer better explanation.KEY WORDS: Environmental equity and justice; Locally unwanted lane uses; Siting; Market dynamics; Invasion-succession; Neighborhood changes 相似文献
4.
5.
NewmethodfordeterminationofarseniccontentintailgasesduringsemiconductorprocessingWenRuimei,PengYongqin(Instituteofmicroconduc... 相似文献
7.
8.
Torvanger Asbjørn Rypdal Kristin Kallbekken Steffen 《Mitigation and Adaptation Strategies for Global Change》2005,10(4):693-715
Carbon dioxide (CO2) capture and storage is increasingly being considered as an important climate change mitigation option. This paper explores
provisions for including geological CO2 storage in climate policy. The storage capacity of Norway's Continental Shelf is alone sufficient to store a large share
of European CO2 emissions for many decades. If CO2 is injected into oil reservoirs there is an additional benefit in terms of enhanced oil recovery. However, there are significant
technical and economic challenges, including the large investment in infrastructure required, with related economies of scale
properties. Thus CO2 capture, transportation and storage projects are likely to be more economically attractive if developed on a large scale,
which could mean involving two or more nations. An additional challenge is the risk of future leakages from storage sites,
where the government must take on a major responsibility. In institutional and policy terms, important challenges are the
unsettled status of geological CO2 storage as a policy measure in the Kyoto Protocol, lack of relevant reporting and verification procedures, and lack of decisions
on how the option should be linked to the flexibility mechanisms under the Kyoto Protocol. In terms of competitiveness with
expected prices for CO2 permits under Kyoto Protocol trading, the relatively high costs per tonne of CO2 stored means that geological CO2 storage is primarily of interest where enhanced oil recovery is possible. These shortcomings and uncertainties mean that
companies and governments today only have weak incentives to venture into geological CO2 storage. 相似文献
9.
10.