全文获取类型
收费全文 | 727篇 |
免费 | 87篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 5篇 |
废物处理 | 4篇 |
环保管理 | 177篇 |
综合类 | 108篇 |
基础理论 | 467篇 |
污染及防治 | 12篇 |
评价与监测 | 30篇 |
社会与环境 | 36篇 |
出版年
2024年 | 3篇 |
2023年 | 35篇 |
2022年 | 31篇 |
2021年 | 34篇 |
2020年 | 36篇 |
2019年 | 25篇 |
2018年 | 19篇 |
2017年 | 30篇 |
2016年 | 35篇 |
2015年 | 33篇 |
2014年 | 29篇 |
2013年 | 35篇 |
2012年 | 26篇 |
2011年 | 34篇 |
2010年 | 33篇 |
2009年 | 46篇 |
2008年 | 46篇 |
2007年 | 46篇 |
2006年 | 44篇 |
2005年 | 39篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 19篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有839条查询结果,搜索用时 15 毫秒
771.
In human-dominated landscapes, interactions and perceptions towards wildlife are influenced by multidimensional drivers. Understanding these drivers could prove useful for wildlife conservation. We surveyed the attitudes and perceptions of fishers towards threatened Irrawaddy dolphins (Orcaella brevirostris) at Chilika Lagoon India. To validate the drivers of fisher perceptions, we : (1) observed dolphin foraging behavior at stake nets, and (2) compared catch per unit effort (CPUE) and catch income of fishers from stake nets in the presence and absence of foraging dolphins. We found that fishers were mostly positive towards dolphins, believing that dolphins augmented their fish catch and using culture to express their perceptions. Foraging dolphins were observed spending half their time at stake nets and were associated with significantly higher catch income and CPUE of mullet (Liza sp.), a locally preferred food fish species. Wildlife conservation efforts should use the multidimensional drivers of human–wildlife interactions to involve local stakeholders in management. 相似文献
772.
冬季不同生境下菹草的水质净化效果研究 总被引:2,自引:0,他引:2
在室外通过人工构建静态模拟生态系统,研究冬季不同底质、水深、水质条件下,菹草对水体营养盐的吸收净化效果。结果表明,在不同水深或水质污染程度的相应组实验中,添加土壤改良剂的各组实验的TN、TP、NO3--N、高锰酸盐指数去除率均高于相应的未添加组,而NH4+-N去除情况相反;添加土壤改良剂有助于菹草对水体营养盐的综合去除,菹草在水深较深且营养盐负荷较高的水体中对营养盐的去除效果更好;水深35cm比水深25cm更适宜菹草的生长;菹草在实验设计的水质条件下能正常生长和对水质进行高效净化,适合在冬季运用于一般河道的水体修复。 相似文献
773.
河流生境质量评价是河流生态系统健康评价的关键之一。本文评价自然和人为作用下的河流生境质量,以南水北调东线工程徐州段丰县、邳州两市输水通道上的河流为研究对象,结合环境特点,选择了反映河道生境、河岸生境和滨岸带生境的10个指标,给出了每个指标的评价方法和5级标准特征值,建立河流生境质量评价体系,确定评价指标的等级标准,对研究区内16个河段的生境质量状况进行综合评价。结果表明:(1)河流生境质量指数(IRHQ)综合得分介于33~91。根据评价等级划分标准,其中有50%的河段生境质量达到"优"等,其余介于"良"等到"劣"等,河流生境质量整体状况良好。(2)河流生境质量指数与NH_4~+-N、COD、TN呈负相关,与DO呈正相关,多项生境指标也与水质指标具有相关性,表明生境质量与水质的相互影响。 相似文献
774.
江西大鄣山夏季鸟类群落多样性研究 总被引:1,自引:0,他引:1
2009年6月至2010年8月采用样线法对江西大鄣山夏季鸟类资源及其生境分布状况进行调查,并计算其物种多样性、均匀性、优势度及不同生境群落间的相似性。共记录江西大鄣山夏季鸟类13目31科78种,其中留鸟45种,夏候鸟21种,冬候鸟7种,旅鸟5种;其中国家二级保护鸟类6种,省级保护鸟类22种;结果表明:东洋种鸟类占有明显优势(500%),古北种次之(282%),广布种占218%。白头鹎(〖WTBX〗Pycnonotus sinensis)和白腰文鸟(Lonchura striata〖WTBZ〗)为当季优势种。6种群落类型中,Shannon Weiner指数与Simpson指数排序均为:阔叶林>农田居民区>针阔混交林>溪流水域>灌木草丛>针叶林。Pielou指数排序为:针阔混交林>溪流水域>阔叶林>农田居民区>灌木草丛>针叶林。Sorenson指数中阔叶林 针阔混交林(〖WTBX〗S〖WTBZ〗=048)为最高。研究结果可为当地森林管理和鸟类保护提供依据 相似文献
775.
Christopher A. Pocknee Sarah M. Legge Jane McDonald Diana O. Fisher 《Conservation biology》2023,37(4):e14062
Fire has shaped ecological communities worldwide for millennia, but impacts of fire on individual species are often poorly understood. We performed a meta-analysis to predict which traits, habitat, or study variables and fire characteristics affect how mammal species respond to fire. We modeled effect sizes of measures of population abundance or occupancy as a function of various combinations of these traits and variables with phylogenetic least squares regression. Nine of 115 modeled species (7.83%) returned statistically significant effect sizes, suggesting most mammals are resilient to fire. The top-ranked model predicted a negative impact of fire on species with lower reproductive rates, regardless of fire type (estimate = –0.68), a positive impact of burrowing in prescribed fires (estimate = 1.46) but not wildfires, and a positive impact of average fire return interval for wildfires (estimate = 0.93) but not prescribed fires. If a species’ International Union for Conservation of Nature Red List assessment includes fire as a known or possible threat, the species was predicted to respond negatively to wildfire relative to prescribed fire (estimate = –2.84). These findings provide evidence of experts’ abilities to predict whether fire is a threat to a mammal species and the ability of managers to meet the needs of fire-threatened species through prescribed fire. Where empirical data are lacking, our methods provide a basis for predicting mammal responses to fire and thus can guide conservation actions or interventions in species or communities. 相似文献
776.
Shelby C. Carlson Alia M. Dietsch Kristina M. Slagle Jeremy T. Bruskotter 《Conservation biology》2023,37(2):e14003
As conservation scholars increasingly recognize the critical role of human thought and behavior in determining the persistence of biodiversity across the globe, a growing line of inquiry regarding the validity and comparability of previous applications of core psychological concepts has emerged. Specifically, inconsistent measurement and use of terms, such as attitudes and acceptance, reveal important questions about previous approaches. Given that these concepts differ by definition, yet have been used interchangeably, we explored what drives differences in people's responses when each concept is operationalized in the context of a contested wildlife species, the gray wolf (Canis lupus). To do so, we used data from a 2014 survey of U.S. residents (n = 1287) to test how measures of six concepts (i.e., acceptance, attitudes, benefits, risks, [prior] behavior, and behavioral intentions) often employed in the conservation social sciences were related with a broad set of possible explanatory variables. Despite moderate to strong correlations between all concepts measured (| Pearson's r | = 0.39–0.65, p < 0.001), results revealed considerable variation in their respective relationships with identical explanatory variables. Specifically, although wildlife value orientation (i.e., domination or mutualism) operated fairly consistently across cognitive and behavioral concepts, the relationship between the six concepts and other factors, such as social trust, identification with various interest groups (i.e., hunter, farmer, or rancher, environmentalist, and animal rights advocate), and political ideology (i.e., liberal vs. conservative), varied considerably. Our findings underscore that differences exist in these measures, which could have serious implications for conservationists integrating social science findings in their decision-making processes if they are unaware of the theoretical underpinnings of and distinctions between core psychological concepts. 相似文献
777.
Daniel Kozák Marek Svitok Veronika Zemlerová Martin Mikoláš Thibault Lachat Laurent Larrieu Yoan Paillet Arne Buechling Radek Bače William S. Keeton Lucie Vítková Krešimir Begovič Vojtěch Čada Martin Dušátko Matej Ferenčík Michal Frankovič Rhiannon Gloor Jeňýk Hofmeister Pavel Janda Ondrej Kameniar Tomáš Kníř Linda Majdanová Marek Mejstřík Jakob Pavlin Dheeraj Ralhan Ruffy Rodrigo Catalin-Constantin Roibu Michal Synek Ondřej Vostarek Miroslav Svoboda 《Conservation biology》2023,37(3):e14066
Protecting structural features, such as tree-related microhabitats (TreMs), is a cost-effective tool crucial for biodiversity conservation applicable to large forested landscapes. Although the development of TreMs is influenced by tree diameter, species, and vitality, the relationships between tree age and TreM profile remain poorly understood. Using a tree-ring-based approach and a large data set of 8038 trees, we modeled the effects of tree age, diameter, and site characteristics on TreM richness and occurrence across some of the most intact primary temperate forests in Europe, including mixed beech and spruce forests. We observed an overall increase in TreM richness on old and large trees in both forest types. The occurrence of specific TreM groups was variably related to tree age and diameter, but some TreM groups (e.g., epiphytes) had a stronger positive relationship with tree species and elevation. Although many TreM groups were positively associated with tree age and diameter, only two TreM groups in spruce stands reacted exclusively to tree age (insect galleries and exposed sapwood) without responding to diameter. Thus, the retention of trees for conservation purposes based on tree diameter appears to be a generally feasible approach with a rather low risk of underrepresentation of TreMs. Because greater tree age and diameter positively affected TreM development, placing a greater emphasis on conserving large trees and allowing them to reach older ages, for example, through the establishment of conservation reserves, would better maintain the continuity of TreM resource and associated biodiversity. However, this approach may be difficult due to the widespread intensification of forest management and global climate change. 相似文献
778.
Richard A. Valdez Colleen Cunningham Ali Effati Deborah L. Freeman 《Journal of the American Water Resources Association》2023,59(5):1084-1098
Warmwater fish habitat in the San Juan River of the southwestern United States has been reduced by over 30% as a result of water depletion, reservoir inundation, and cold-water dam releases combined with drought-related changes in hydrology. This reduction and a suite of other factors have contributed to declines in native fish populations including the federally endangered Colorado Pikeminnow (Ptychocheilus lucius) and Razorback Sucker (Xyrauchen texanus). Conservation efforts for these species include determining flow needs; protecting, managing, and augmenting habitats; and stocking hatchery fish. But the young of stocked fish have low survival due largely to a paucity of nursery habitat not being reformed and maintained under current conditions. Flow recommendations for Navajo Dam releases designed to mimic the river's natural hydrograph have not been met due to water shortages, and the desired outcomes of increased channel complexity and enhanced fish habitat have not been observed. Forecasted hydrology that includes ongoing drought shows that achieving the flow targets through further dam reoperations is unlikely. Mechanical construction of early life-stage habitats is a highly recommended complement to flow management for offsetting the effects of flow reduction and habitat loss. Habitats with features that are effective and resilient under a range of flows are important in counterbalancing the effects of climate change. 相似文献
779.
成都市河流生态健康评价 总被引:2,自引:2,他引:0
研究以成都市域内河流为研究对象,通过采样分析得到水质、生境状况、浮游藻类、底栖动物等相关指标,利用综合指标体系法,评价成都市域内河流生态系统健康状况,并结合成都市人口、土地利用、地区生产总值等因素分析人类活动与河流生态健康的关系。结果表明:成都市河流浮游藻类以硅藻和绿藻为主,部分中下游采样点出现以蓝藻为主的情况;底栖动物以指示有机污染的颤蚓科出现的频率最高,约48%的采样点以颤蚓科为优势种;约74%的河流生态健康状况为"差"或"很差",河流生态健康状况整体呈现中上游优于下游、城市周边优于市区的特征;人口密度、人类活动用地比例与河流中氨氮呈显著正相关,人类活动会显著影响河流生态系统健康。 相似文献
780.
Abstract: Stream and riparian managers must effectively allocate limited financial and personnel resources to monitor and manage riparian ecosystems. They need to use management strategies and monitoring methods that are compatible with their objectives and the response potential of each stream reach. Our objective is to help others set realistic management objectives by comparing results from different methods used to document riparian recovery across a diversity of stream types. The Bureau of Land Management Elko Field Office, Nevada, used stream survey, riparian proper functioning condition (PFC) assessment, repeat photographic analysis, and stream and ecological classification to study 10 streams within the Marys River watershed of northeast Nevada during all or parts of 20 years. Most riparian areas improved significantly from 1979 to 1992‐1993 and then additionally by 1997‐2000. Improvements were observed in riparian and habitat condition indices, bank cover, and stability, pool quality, bank angle, and depth of undercut bank. Interpretation of repeat photography generally confirmed results from stream survey and should be part of long‐term riparian monitoring. More attributes of Rosgen stream types C and E improved than of types B and F. A and Gc streams did not show significant improvement. Alluvial draws and alluvial valleys improved in more ways than V‐erosional canyons and especially V‐depositional canyons. Stream survey data could not be substituted for riparian PFC assessment. Riparian PFC assessments help interpret other data. 相似文献