首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9625篇
  免费   0篇
废物处理   765篇
环保管理   1207篇
综合类   932篇
基础理论   3103篇
污染及防治   1720篇
评价与监测   1004篇
社会与环境   894篇
  2019年   1篇
  2018年   1473篇
  2017年   1371篇
  2016年   1193篇
  2015年   123篇
  2014年   13篇
  2013年   5篇
  2012年   458篇
  2011年   1337篇
  2010年   688篇
  2009年   596篇
  2008年   876篇
  2007年   1226篇
  2006年   1篇
  2005年   18篇
  2004年   32篇
  2003年   61篇
  2002年   97篇
  2001年   14篇
  2000年   10篇
  1999年   2篇
  1998年   9篇
  1984年   11篇
  1983年   8篇
  1935年   2篇
排序方式: 共有9625条查询结果,搜索用时 250 毫秒
121.
Loss of zooxanthellae (dinoflagellate Symbiodinium) from corals will sometimes lead to mass mortality of corals. To detect and quantify Symbiodinium released from corals, we developed a zooxanthellae “trap” and a quantitative PCR (qPCR) system with Symbiodinium clades A–F-specific primer sets. The trap was attached to a branch or the surface of several wild stony corals, and the water samples within the traps, including released Symbiodinium, were subjected to qPCR. All tested corals released clade C Symbiodinium at estimates of ~5,900 cells h−1 cm−2 of coral surface. Although all tested Pocillopora eydouxi harboured both clades C and D, some of these colonies released only clade C or released a lesser amount of clade D than that in the tissues. Our Symbiodinium quantification system revealed that wild hermatypic corals constantly release Symbiodinium to the environment. Our result suggests that some corals may discharge certain clades of Symbiodinium alternatively.  相似文献   
122.
123.
Global marine capture fisheries are undergoing serious stress, with overfishing as one of the major problems. In order to mitigate the overexploitation of capture fisheries, government regulation or fisheries management is necessary. Among various management approaches, vessel quantity control is being widely employed. To achieve effective governance of fisheries, the technical efficiency (TE) issue needs to be considered in the implementation of vessel quantity control. Using the Pacific saury (Cololabis saira) stick-held dip net fishery in Japan as a case study, this paper estimated the TE of sampled fishing vessels and explored the possible factors affecting the gap in efficiency. This paper aims to provide suggestions for a better implementation of vessel quantity control in global Pacific saury fishery, and also to serve as an empirical example of integrating TE analysis into management of overexploited fisheries for achieving satisfactory effects. Results show the TE score of the sampled fishery averaged around 0.7 from 2009 to 2014, and factors concerning owners/skippers’ motivation such as vessel ownership and specialization, vessel tonnage as well as skippers’ age show positive effects on the TE. Our findings in the present work provide important strategies for mitigating overexploitation in fisheries. Conducting technical efficiency analysis of targeted fisheries is a vital issue to be considered for designing and realizing an effective implementation of fisheries management approaches. The large vessels and the enthusiasm of vessel owners/skippers need to be particularly addressed when vessel quantity limit is considered to mitigate the problem of overfishing.  相似文献   
124.
Assessment of vulnerability is an important step in building long-term resilience in the forestry sector. The objective of this paper is to present a methodological approach to assess inherent vulnerability of forests at landscape level. The approach involves use of vulnerability indicators, the pairwise comparison method, and geographic information system (GIS) tools. We apply this approach to assess the inherent vulnerability of forests of the Western Ghats Karnataka (WGK) landscape, which is a part of the Western Ghats biodiversity hotspot in India. Four vulnerability indicators, namely biological richness, disturbance index, canopy cover, and slope, are selected. We find that forests in 30, 36, 19, and 15 % grid points in this region show low, medium, high, and very high inherent vulnerability, respectively. The forest showing high and very high inherent vulnerability are mostly dry deciduous forests and plantations located largely on the eastern side of the landscape. We also find that canopy cover is one of the key indicators that determine the inherent vulnerability of forests, and natural forests are inherently less vulnerable than man-made plantations. Spatial assessment of inherent vulnerability of forests at landscape level is particularly useful for developing strategies to build resilience to current stressors and climate change in future.  相似文献   
125.
Sandy beach habitat where sea turtles nest will be affected by multiple climate change impacts. Before these impacts occur, knowledge of how nest site selection and hatching success vary with beach microhabitats is needed to inform managers on how to protect suitable habitats and prepare for scientifically valid mitigation measures at beaches around the world. At a highly successful green turtle (Chelonia mydas) rookery at Akumal, Quintana Roo, Mexico, we measured microhabitat characteristics along the beach crawl (rejected sites) and related nest site conditions (selected sites) to subsequent hatching success rates for 64 nesting events. To our knowledge, this is the first study to report environmental data along the nesting crawl for a green turtle population and the first to use natural breaks in the data to describe their preferred habitat ranges. Our results indicate that turtles were likely using a combination of cues to find nest sites, mainly higher elevations and lower sand surface temperatures (Kruskal-Wallis test, H?=?19.84, p?<?0.001; H?=?10.78, p?<?0.001). Hatching success was significantly and negatively correlated to sand temperature at cloaca depth (Spearman’s ρ?=??0.27, p?=?0.04). Indeed, the preferred range for cloaca sand temperatures at the nest site (26.3–27.5 °C) had significantly higher hatching success rates compared to the highest temperature range (Tukey HSD?=?0.47, p?=?0.05). Sand temperatures at various depths were intercorrelated, and surface and cloaca depth sand temperatures were correlated to air temperature (ρ?=?0.70, p?=?0.00; ρ?=?0.26, p?=?0.04). Therefore, rising air temperatures could alter sand temperature cues for suitable nest sites, preferred nest site ranges, and produce uneven sex ratios or lethal incubating temperatures. Elevation cues and preferred ranges (1.4–2.5 m) may also be affected by sea level rise, risking inundation of nests.  相似文献   
126.
India being a developing economy dependent on climate-sensitive sector like agriculture is highly vulnerable to impacts of global climate change. Vulnerability to climate change, however, differs spatially within the country owing to regional differences in exposure, sensitivity, and adaptive capacity. The study uses the Hadley Centre Global Environment Model version 2-Earth System (HadGEM-ES) climate projections to assess the dynamics in vulnerability across four climate change exposure scenarios developed using Representative Concentration Pathways (RCPs). The analysis was carried out at subnational (district) level; the results were interpreted and reported for their corresponding agro-ecological zones. Vulnerability of each district was quantified using indicators capturing climatic variability, ecological and demographic sensitivity, and socio-economic capacity. Our analysis further assigns probabilities to vulnerability classes of all the 579 districts falling under different agro-ecological zones. The results of the vulnerability profile show that Western plains, Northern plains, and central highlands of the arid and semi-arid agro-ecological zones are the most vulnerable regions in the current scenario (1950–2000). In the future scenario (2050), it extends along districts falling within Deccan plateau and Central (Malwa) highlands, lying in the arid and semi-arid zones, along with regions vulnerable in the current scenario, recording the highest vulnerability score across all exposure scenarios. These regions exhibit highest degree of variation in climatic parameters, ecological fragility, socio-economic marginality, and limited accessibility to resources, generating conditions of high vulnerability. The study emphasizes on the priority to take up adaptive management actions in the identified vulnerable districts to not only reduce risks of climate change, but also enhance their inherent capacity to withstand any future changes in climate. It provides a systematic approach to explicitly identify vulnerable regions, where regional planners and policy makers can build on existing adaptation decision-making by utilizing an interdisciplinary approach in the context of global change scenario.  相似文献   
127.
Forests play a fundamental role in the global carbon cycle and can be managed to mitigate greenhouse gas emissions and conserve or sequester carbon. Global policy and environmental changes can affect regional consumption of forest products, as well as inter-regional trade of forest goods and services. This study analyzes global and regional change impacts on the production, consumption and trade of forest products in two Nordic countries, Finland and Sweden. Annual data on removal and trade (1964–2012) for roundwood and sawnwood is used to identify structural breaks based on Chow tests. According to the analysis, the time period is divided into two periods: t1 (1964–1980) and t2 (1981–2012). In the first period, breaks occurred in 1975 and 1976 in the Finnish model and no break is found in the Swedish model. In the second period, we identify breaks in 1991 and 1992 for the Finnish model and in 2004, 2005 and 2006 for the Swedish model. Although our findings have broad empirical support, we do not identify any specific incident as a direct cause of the changes in the consumption and trade patterns of the two types of wood in these countries. The models and analysis presented here can serve as methodological tools for policymakers to better understand the effects of structural changes in the production of forest goods and services in the Nordic region and globally.  相似文献   
128.
After extensive flooding in 2002, the European Union Solidarity Fund (EUSF) was created as an ex post loss-financing vehicle for EU member states and candidate countries in the case of disasters that exceed the government’s resources to cope. The EUSF is viewed as a valuable instrument for pooling risk among countries in Europe and potentially as a model for financing loss and damage from climate change in vulnerable countries worldwide. This paper assesses its future prospects taking account of reforms adopted in 2014. Our analysis is based on three recognized aims of the Solidarity Fund: its promotion of solidarity with those countries having the least capacity to cope with major disasters; its contribution to proactive disaster risk reduction and management (climate adaptation); and its robustness with regard to its risk of depletion (stress testing). Using a simulation approach for future disasters, we conclude that the reformed EUSF’s risk of depletion, although it is reasonably robust to more frequent disasters, could be reduced by increasing member state contributions and/or engaging in risk transfer. The European Commission has taken important steps in linking the fund to proactive risk reduction; yet, by changing its budgeting practices, the commission could be more proactive in encouraging risk management in member states. In its current form, the EUSF does not embed needs-based solidarity. Lower-income “new” member states have received disproportionately less compensation in terms of eligible losses, although on average, they have received more disaster aid than what they contribute to the fund. Solidarity could be enhanced by changing the rules for disbursing aid. After briefly describing alternative risk-pooling models in the Caribbean, Africa, and Europe, we suggest how design features of the EUSF as compared to other regional risk pools can inform discussions on the Warsaw International Loss and Damage Mechanism.  相似文献   
129.
We present a methodology for using a domestic water use time series that were obtained from Yellow River Conservancy Commission, together with the climatic records from the National Climate Center of China to evaluate the effects of climate variability on water use in the Yellow River Basin. A suit of seven Global Circulation Models (GCMs) were adopted to anticipate future climate patterns in the Yellow River. The historical records showed evidences of rises in temperature and subsequent rises in domestic water demand in the basin. For Upstream of Longyangxia region, the impact was the least, with only 0.0021?×?108 m3 for a temperature increase of 1 °C; while for Longyangxia-Lanzhou region, domestic water use was found to increase to 0.18?×?108 m3 when temperature increases 1 °C. Downstream of Huayuankou was the region with the most changes in temperature that gave the highest increase of 1.95?×?108 m3 in domestic water demand for 1 °C of change of temperature. Downstream of Huayuankou was identified as the most vulnerable area, where domestic water demand increases nearly by 42.2 % with 1 °C increase of temperature. Judging from the trends of temperature range, we concluded that future temperature in Yellow River Basin has an increasing tendency. This could worsen the existing issues of domestic water demand and even more to trigger high competition among different water-using sectors.  相似文献   
130.
Institutions are one of the decisive factors which enable, constrain and shape adaptation to the impacts of climate change, variability and extreme events. However, current understanding of institutions in adaptation situations is fragmented across the scientific community, evidence diverges, and cumulative learning beyond single studies is limited. This study adopts a diagnostic approach to elaborate a nuanced understanding of institutional barriers and opportunities in climate adaptation by means of a model-centred meta-analysis of 52 case studies of public climate adaptation in Europe. The first result is a novel taxonomy of institutional attributes in adaptation situations. It conceptually organises and decomposes the many details of institutions that empirical research has shown to shape climate adaptation. In the second step, the paper identifies archetypical patterns of institutional traps and trade-offs which hamper adaptation. Thirdly, corresponding opportunities are identified that enable actors to alleviate, prevent or overcome specific institutional traps or trade-offs. These results cast doubt on the validity of general institutional design principles for successful adaptation. In contrast to generic principles, the identified opportunities provide leverage to match institutions to specific governance problems that are encountered in specific contexts. Taken together, the results may contribute to more coherence and integration of adaptation research that we need if we are to foster learning about the role of institutions in adaptation situations in a cumulative fashion.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号