全文获取类型
收费全文 | 2126篇 |
免费 | 245篇 |
国内免费 | 670篇 |
专业分类
安全科学 | 74篇 |
废物处理 | 35篇 |
环保管理 | 249篇 |
综合类 | 1111篇 |
基础理论 | 1144篇 |
污染及防治 | 179篇 |
评价与监测 | 77篇 |
社会与环境 | 162篇 |
灾害及防治 | 10篇 |
出版年
2024年 | 8篇 |
2023年 | 61篇 |
2022年 | 105篇 |
2021年 | 107篇 |
2020年 | 137篇 |
2019年 | 100篇 |
2018年 | 88篇 |
2017年 | 105篇 |
2016年 | 115篇 |
2015年 | 141篇 |
2014年 | 123篇 |
2013年 | 186篇 |
2012年 | 163篇 |
2011年 | 196篇 |
2010年 | 148篇 |
2009年 | 146篇 |
2008年 | 142篇 |
2007年 | 182篇 |
2006年 | 118篇 |
2005年 | 119篇 |
2004年 | 88篇 |
2003年 | 77篇 |
2002年 | 56篇 |
2001年 | 46篇 |
2000年 | 47篇 |
1999年 | 32篇 |
1998年 | 31篇 |
1997年 | 30篇 |
1996年 | 30篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1984年 | 6篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3041条查询结果,搜索用时 343 毫秒
861.
我院校园木本植物物种多样性调查与分析评价 总被引:1,自引:1,他引:1
对中国环境管理干部学院校园内现有的木本植物进行了种类统计和鉴定,发现校园内大部分木本植物生长良好,但是部分木本植物因人为破坏、气候不适而生长不良甚至死亡。我们应该提高认识、明确方向、优化结构、利用资源、加强养护,对校园植物资源进行管护。 相似文献
862.
/ Adaptive ecosystem management seeks to sustain ecosystems while extracting or using natural resources. The goal of endangered species management under the Endangered Species Act is limited to the protection and recovery of designated species, and the act takes precedence over other policies and regulations guiding ecosystem management. We present an example of conflict between endangered species and ecosystem management during the first planned flood on the Colorado River in Grand Canyon in 1996. We discuss the resolution of the conflict and the circumstances that allowed a solution to be reached. We recommend that adaptive management be implemented extensively and early in ecosystem management so that information and working relationships will be available to address conflicts as they arise. Though adaptive management is not a panacea, it offers the best opportunity for balanced solutions to competing management goals. 相似文献
863.
864.
Preventing the introduction of nonindigenous species (NIS) is the most efficient way to avoid the costs and impacts of biological invasions. The transport of fouling species on ship hulls is an important vector for the introduction of marine NIS. We use quantitative risk screening techniques to develop a predictive tool of the abundance and variety of organisms being transported by ocean-going yachts. We developed and calibrated an ordinal rank scale of the abundance of fouling assemblages on the hulls of international yacht hulls arriving in New Zealand. Fouling ranks were allocated to 783 international yachts that arrived in New Zealand between 2002 and 2004. Classification tree analysis was used to identify relationships between the fouling ranks and predictor variables that described the maintenance and travel history of the yachts. The fouling ranks provided reliable indications of the actual abundance and variety of fouling assemblages on the yachts and identified most (60%) yachts that had fouling on their hulls. However, classification tree models explained comparatively little of the variation in the distribution of fouling ranks (22.1%), had high misclassification rates (∼43%), and low predictive power. In agreement with other studies, the best model selected the age of the toxic antifouling paint on yacht hulls as the principal risk factor for hull fouling. Our study shows that the transport probability of fouling organisms is the result of a complex suite of interacting factors and that large sample sizes will be needed for calibration of robust risk models. 相似文献
865.
866.
干旱河谷地区农业产业结构的调整对环境及经济的影响分析--以汉源地区为例 总被引:1,自引:1,他引:1
中国农业产业结构的调整,是中国改革开放、市场化发展的集中体现。本文以汉源地区为例,总结分析了典型的干旱河谷地带农业产业结构的调整情况,不仅促进了当地农村发展方式的根本转变、改善了农村经济、提高了农民收入,同时还解决了当地剩余劳动力的就地消化问题。本文指出了农业产业结构的调整可能对当地生态环境造成的影响,其中诸如不舍理用药用肥造成的水污染、土壤和农产品的硝酸盐污染以及土壤退化、大气污染等环境问题。需要在实践中更加审慎地调整农业产业结构。 相似文献
867.
Bjørn K. Myskja 《Journal of Agricultural and Environmental Ethics》2006,19(3):225-238
Public policy on the development and use of genetically modified organisms (GMOs) has mainly been concerned with defining proper strategies of risk management. However, surveys and focus group interviews show that although lay people are concerned with risks, they also emphasize that genetic modification is ethically questionable in itself. Many people feel that this technology “tampers with nature” in an unacceptable manner. This is often identified as an objection to the crossing of species borders in producing transgenic organisms. Most scientists reject these opinions as based on insufficient knowledge about biotechnology, the concept of species, and nature in general. Some recent projects of genetic modification aim to accommodate the above mentioned concerns by altering the expression of endogenous genes rather than introducing genes from other species. There can be good scientific reasons for this approach, in addition to strategic reasons related to greater public acceptability. But are there also moral reasons for choosing intragenic rather than transgenic modification? I suggest three interrelated moral reasons for giving priority to intragenic modification. First, we should respect the opinions of lay people even when their view is contrary to scientific consensus; they express an alternative world-view, not scientific ignorance. Second, staying within species borders by strengthening endogenous traits reduces the risks and scientific uncertainty. Third, we should show respect for nature as a complex system of laws and interconnections that we cannot fully control. The main moral reason for intragenic modification, in our view, is the need to respect the “otherness” of nature. 相似文献
868.
Alan E. Haberstock Henry G. Nichols Mark P. DesMeules Jed Wright Jon M. Christensen Daniel H. Hudnut 《Journal of the American Water Resources Association》2000,36(6):1271-1286
ABSTRACT: Successful restoration of declining anadromous species is dependent upon effective riparian buffer zone management. Natural resource managers, policy developers and local conservation groups require science‐based information concerning the width at which a given buffer will be effective for its stated purpose. This paper summarizes a method developed in 1999 to determine effective riparian buffer widths for Atlantic salmon habitat protection as part of the Atlantic Salmon Conservation Plan for Seven Maine Rivers. A major assumption of the method is that no two buffers are alike with respect to their effectiveness and that various buffer characteristics dictate the required width for a given level of effectiveness. The method uses a predictive model that generates suggested riparian buffer widths as a function of specific, measurable buffer characteristics (such as slope, soil characteristics, and plant community structure and density) that affect buffer function. The method utilizes a variable‐width, two‐zone approach and specifies land uses that are consistent with desired buffer function within the two zones. 相似文献
869.
Trichodiene, a volatile sesquiterpene which is structurally related to trichothecene mycotoxins, has been identified in the
headspace of growing Stachybotrys chartarum by GC/MS. It is possible that volatile sesquiterpene patterns can be used to characterize S. chartarum and related mold isolates as trichothecene producers, thus providing clear criteria for decisions concerning the occupancy
and renovation of contaminated buildings. 相似文献
870.
E. A. Platonova 《Russian Journal of Ecology》2001,32(6):375-381
The distribution of tree species in the landscape was studied using the approach based on the comparison of the ecological requirements of species and the properties of ecotopes distinguished by their position in the relief and peculiarities of basement rocks. The types and specificity of ecological regimes were determined for the typical ecotopes of the southern Karelian ridge landscape. The main environmental and successional factors determining the distribution of seven forest-forming tree species in the ecotopes of this landscape were identified. The results of this work can provide a basis for the prognosis of forest vegetation in the landscape studied. 相似文献