全文获取类型
收费全文 | 1662篇 |
免费 | 189篇 |
国内免费 | 472篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 12篇 |
环保管理 | 195篇 |
综合类 | 752篇 |
基础理论 | 1017篇 |
污染及防治 | 125篇 |
评价与监测 | 70篇 |
社会与环境 | 114篇 |
灾害及防治 | 4篇 |
出版年
2024年 | 4篇 |
2023年 | 39篇 |
2022年 | 65篇 |
2021年 | 72篇 |
2020年 | 91篇 |
2019年 | 68篇 |
2018年 | 64篇 |
2017年 | 84篇 |
2016年 | 84篇 |
2015年 | 101篇 |
2014年 | 93篇 |
2013年 | 138篇 |
2012年 | 120篇 |
2011年 | 161篇 |
2010年 | 113篇 |
2009年 | 120篇 |
2008年 | 120篇 |
2007年 | 151篇 |
2006年 | 94篇 |
2005年 | 111篇 |
2004年 | 75篇 |
2003年 | 60篇 |
2002年 | 42篇 |
2001年 | 29篇 |
2000年 | 37篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 24篇 |
1995年 | 16篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2323条查询结果,搜索用时 31 毫秒
681.
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
682.
为了实现油(气)田(特别是环境敏感地区)开发的可持续发展,在原有基础上,针对水网地区油田开发环境的特点,就现在环境保护技术工作中存在的重点难点问题进行进一步的研究和探讨,完善和发展了整套污染防治工艺、处理技术及处理装备。 相似文献
683.
青山水库底栖动物群落初步研究 总被引:9,自引:0,他引:9
1996年10月-1997年7月对青山水库底栖大型无脊椎动物群落进行了4次采样调查,共发现大型底栖无脊椎动物16种,其中寡毛类5种,水生昆虫7种,软件动物2种,蛭类和线虫各1种。青山水库底栖动物群落密度和生物量的水平变化为库出口>库中心>进口。湖区底栖动物群落占优势的各类为:刺夹长足摇蚊(Tanypus punctipennis)、花翅前突摇蚊(Procladius choreus)和霍甫水丝蚓(Limnodrilus hoffmeisteri)。调查结果表明,目前青山水库底栖动物群落的种类组成指示该水体已属富营养型,但从生物量上分析,目前青山水库应属中营养。 相似文献
684.
Incorporating anthropogenic variables into a species distribution model to map gypsy moth risk 总被引:1,自引:0,他引:1
Christopher D. Lippitt John Rogan James Toledano Florencia Sangermano J. Ronald Eastman Victor Mastro Alan Sawyer 《Ecological modelling》2008
This paper presents a novel methodology for multi-scale and multi-type spatial data integration in support of insect pest risk/vulnerability assessment in the contiguous United States. Probability of gypsy moth (Lymantria dispar L.) establishment is used as a case study. A neural network facilitates the integration of variables representing dynamic anthropogenic interaction and ecological characteristics. Neural network model (back-propagation network [BPN]) results are compared to logistic regression and multi-criteria evaluation via weighted linear combination, using the receiver operating characteristic area under the curve (AUC) and a simple threshold assessment. The BPN provided the most accurate infestation-forecast predictions producing an AUC of 0.93, followed by multi-criteria evaluation (AUC = 0.92) and logistic regression (AUC = 0.86) when independently validating using post model infestation data. Results suggest that BPN can provide valuable insight into factors contributing to introduction for invasive species whose propagation and establishment requirements are not fully understood. The integration of anthropogenic and ecological variables allowed production of an accurate risk model and provided insight into the impact of human activities. 相似文献
685.
An Assessment of Invasion Risk from Assisted Migration 总被引:4,自引:0,他引:4
Abstract: To reduce the risk of extinction due to climate change, some ecologists have suggested human-aided translocation of species, or assisted migration (AM), to areas where climate is projected to become suitable. Such intentional movement, however, may create new invasive species if successful introductions grow out of control and cause ecologic or economic damage. We assessed this risk by surveying invasive species in the United States and categorizing invaders based on origin. Because AM will involve moving species on a regional scale within continents (i.e., range shifts), we used invasive species with an intracontinental origin as a proxy for species that would be moved through AM. We then determined whether intracontinental invasions were more prevalent or harmful than intercontinental invasions. Intracontinental invasions occurred far less frequently than invasions from other continents, but they were just as likely to have had severe effects. Fish and crustaceans pose a particularly high threat of intracontinental invasion. We conclude that the risk of AM to create novel invasive species is small, but assisted species that do become invasive could have large effects. Past experience with species reintroductions may help inform policy regarding AM. 相似文献
686.
Managing Aquatic Species of Conservation Concern in the Face of Climate Change and Invasive Species 总被引:2,自引:0,他引:2
Abstract: The difficult task of managing species of conservation concern is likely to become even more challenging due to the interaction of climate change and invasive species. In addition to direct effects on habitat quality, climate change will foster the expansion of invasive species into new areas and magnify the effects of invasive species already present by altering competitive dominance, increasing predation rates, and enhancing the virulence of diseases. In some cases parapatric species may expand into new habitats and have detrimental effects that are similar to those of invading non-native species. The traditional strategy of isolating imperiled species in reserves may not be adequate if habitat conditions change beyond historic ranges or in ways that favor invasive species. The consequences of climate change will require a more active management paradigm that includes implementing habitat improvements that reduce the effects of climate change and creating migration barriers that prevent an influx of invasive species. Other management actions that should be considered include providing dispersal corridors that allow species to track environmental changes, translocating species to newly suitable habitats where migration is not possible, and developing action plans for the early detection and eradication of new invasive species. 相似文献
687.
Coral Reef Habitats as Surrogates of Species, Ecological Functions, and Ecosystem Services 总被引:3,自引:0,他引:3
PETER J. MUMBY††† KENNETH BROAD† DANIEL R. BRUMBAUGH‡§ CRAIG P. DAHLGREN ALASTAIR R. HARBORNE ALAN HASTINGS†† KATHERINE E. HOLMES‡ CARRIE V. KAPPEL‡‡ FIORENZA MICHELI§§ JAMES N. SANCHIRICO 《Conservation biology》2008,22(4):941-951
Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve networks are designed, but their efficacy as surrogates for species richness and applicability to other conservation measures is poorly understood. Combining an analysis of field survey data, literature review, and expert assessment by a multidisciplinary working group, we examined the degree to which Caribbean coastal habitats provide useful planning information on 4 conservation measures: species richness, the ecological functions of fish species, ecosystem processes, and ecosystem services. Approximately one‐quarter to one‐third of benthic invertebrate species and fish species (disaggregated by life phase; hereafter fish species) occurred in a single habitat, and Montastraea‐dominated forereefs consistently had the highest richness of all species, processes, and services. All 11 habitats were needed to represent all 277 fish species in the seascape, although reducing the conservation target to 95% of species approximately halved the number of habitats required to ensure representation. Species accumulation indices (SAIs) were used to compare the efficacy of surrogates and revealed that fish species were a more appropriate surrogate of benthic species (SAI = 71%) than benthic species were for fishes (SAI = 42%). Species of reef fishes were also distributed more widely across the seascape than invertebrates and therefore their use as a surrogate simultaneously included mangroves, sea grass, and coral reef habitats. Functional classes of fishes served as effective surrogates of fish and benthic species which, given their ease to survey, makes them a particularly useful measure for conservation planning. Ecosystem processes and services exhibited great redundancy among habitats and were ineffective as surrogates of species. Therefore, processes and services in this case were generally unsuitable for a complementarity‐based approach to reserve design. In contrast, the representation of species or functional classes ensured inclusion of all processes and services in the reserve network. 相似文献
688.
Abstract: Species range maps based on extents of occurrence (EOO maps) have become the basis for many analyses in broad-scale ecology and conservation. Nevertheless, EOO maps are usually highly interpolated and overestimate small-scale occurrence, which may bias research outcomes. We evaluated geographical range overestimation and its potential ecological causes for 1158 bird species by quantifying EOO map occurrence across 4040 well-studied survey locations in Australia, North America, and southern Africa at the scale of 80–742 km2 . Most species occurred in only 40–70% of the range indicated by their EOO maps. The observed proportional range overestimation affected the range-size frequency distribution, indicating that species are more range-restricted than suggested by EOO maps. The EOO maps most strongly overestimated the distribution of narrow-ranging species and ecological specialists with narrow diet and habitat breadth. These relationships support basic ecological predictions about the relationship between niche breadth and the fine-scale occurrence of species. Consequently, at-risk species were subject to particularly high proportional range overestimation, on average 62% compared with 37% of nonthreatened species. These trends affect broad-scale ecological analyses and species conservation assessments, which will benefit from a careful consideration of potential biases introduced by range overestimation. 相似文献
689.
JESSICA J. HELLMANN JAMES E. BYERS† BRITTA G. BIERWAGEN‡ JEFFREY S. DUKES§ 《Conservation biology》2008,22(3):534-543
Abstract: Scientific and societal unknowns make it difficult to predict how global environmental changes such as climate change and biological invasions will affect ecological systems. In the long term, these changes may have interacting effects and compound the uncertainty associated with each individual driver. Nonetheless, invasive species are likely to respond in ways that should be qualitatively predictable, and some of these responses will be distinct from those of native counterparts. We used the stages of invasion known as the "invasion pathway" to identify 5 nonexclusive consequences of climate change for invasive species: (1) altered transport and introduction mechanisms, (2) establishment of new invasive species, (3) altered impact of existing invasive species, (4) altered distribution of existing invasive species, and (5) altered effectiveness of control strategies. We then used these consequences to identify testable hypotheses about the responses of invasive species to climate change and provide suggestions for invasive-species management plans. The 5 consequences also emphasize the need for enhanced environmental monitoring and expanded coordination among entities involved in invasive-species management. 相似文献
690.
为了及时掌握衡阳市蔬菜产业发展动态,有效的指导衡阳市蔬菜生产,笔者对2006年衡阳市蔬菜品种及产业发展情况进行了调查,主要是摸清蔬菜品种,找出存在的主要问题,提出了下一步蔬菜品种及产业发展措施,把衡阳市蔬菜生产推向一个新的发展水平.表10,参7. 相似文献