全文获取类型
收费全文 | 17208篇 |
免费 | 1242篇 |
国内免费 | 2639篇 |
专业分类
安全科学 | 2619篇 |
废物处理 | 332篇 |
环保管理 | 2837篇 |
综合类 | 9813篇 |
基础理论 | 1524篇 |
环境理论 | 9篇 |
污染及防治 | 1142篇 |
评价与监测 | 789篇 |
社会与环境 | 1168篇 |
灾害及防治 | 856篇 |
出版年
2024年 | 63篇 |
2023年 | 260篇 |
2022年 | 478篇 |
2021年 | 657篇 |
2020年 | 652篇 |
2019年 | 494篇 |
2018年 | 427篇 |
2017年 | 593篇 |
2016年 | 674篇 |
2015年 | 703篇 |
2014年 | 798篇 |
2013年 | 1020篇 |
2012年 | 1166篇 |
2011年 | 1276篇 |
2010年 | 883篇 |
2009年 | 985篇 |
2008年 | 728篇 |
2007年 | 1156篇 |
2006年 | 1144篇 |
2005年 | 1005篇 |
2004年 | 891篇 |
2003年 | 830篇 |
2002年 | 728篇 |
2001年 | 624篇 |
2000年 | 561篇 |
1999年 | 530篇 |
1998年 | 355篇 |
1997年 | 302篇 |
1996年 | 199篇 |
1995年 | 188篇 |
1994年 | 160篇 |
1993年 | 151篇 |
1992年 | 99篇 |
1991年 | 59篇 |
1990年 | 40篇 |
1989年 | 19篇 |
1988年 | 27篇 |
1987年 | 16篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 5篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 973 毫秒
651.
Dalia Streimikiene 《Natural resources forum》2005,29(4):322-333
This article summarizes some of the results from the application of the indicators for sustainable energy development (ISED) tool for analyzing Lithuania's energy sector, in terms of trends, setting energy policy goals and monitoring progress towards these goals. This experience illustrates the potential applicability of the ISED methodology for energy policy development in economies in transition, using Lithuania as an example. The article presents a summary of the results achieved and conclusions arrived at from the analysis of six priority areas in the context of the research project coordinated by the International Atomic Energy Agency, and provides recommendations for the development of sustainable energy policy using the ISED approach. 相似文献
652.
John V. Westra Julie K.H. Zimmerman Bruce Vondracek 《Journal of the American Water Resources Association》2005,41(2):309-322
ABSTRACT: Farmers can generate environmental benefits (improved water quality and fisheries and wildlife habitat), but they may not be able to quantify them. Furthermore, farmers may reduce their incomes from managing lands to produce these positive externalities but receive little monetary compensation in return. This study simulated the relationship between agricultural practices, water quality, fish responses to suspended sediment and farm income within two small watersheds, one of a cool water stream and one of a warm water stream. Using the Agricultural Drainage and Pesticide Transport (ADAPT) model, this study related best management practices (BMPs) to calculated instream suspended sediment concentrations by estimating sediment delivery, runoff, base flow, and streambank erosion to quantify the effects of suspended sediment exposure on fish communities. By implementing selected BMPs in each watershed, annual net farm income declined $18,000 to $28,000 (1 to 3 percent) from previous levels. “Lethal” fish events from suspended sediments in the cool water watershed decreased by 60 percent as conservation tillage and riparian buffers increased. Despite reducing suspended sediments by 25 percent, BMPs in the warm water watershed did not reduce the negative response of the fisheries. Differences in responses (physical and biological) between watersheds highlight potential gains in economic efficiency by targeting BMPs or by offering performance based “green payments.” 相似文献
653.
Glenn A. Hodgkins Robert W. Dudley Thomas G. Huntington 《Journal of the American Water Resources Association》2005,41(2):403-411
ABSTRACT: High springtime river flows came earlier by one to two weeks in large parts of northern New England during the 20th Century. In this study it was hypothesized that late spring/early summer recessional flows and late summer/early fall low flows could also be occurring earlier. This could result in a longer period of low flow recession and a decrease in the magnitude of low flows. To test this hypothesis, variations over time in the magnitude and timing of low flows were analyzed. To help understand the relation between low flows and climatic variables in New England, low flows were correlated with air temperatures and precipitation. Analysis of data from 23 rural, unregulated rivers across New England indicated little evidence of consistent changes in the timing or magnitude of late summer/early fall low flows during the 20th Century. The interannual variability in the timing and magnitude of the low flows in northern New England was explained much more by the interannual variability in precipitation than by the interannual variability of air temperatures. The highest correlation between the magnitude of the low flows and air temperatures was with May through November temperatures (r =?0.37, p= 0.0017), while the highest correlation with precipitation was with July through August precipitation (r = 0.67, p > 0.0001). 相似文献
654.
Anna Eleria Richard M. Vogel 《Journal of the American Water Resources Association》2005,41(5):1195-1209
In Massachusetts, the Charles River Watershed Association conducts a regular water quality monitoring and public notification program in the Charles River Basin during the recreational season to inform users of the river's health. This program has relied on laboratory analyses of river samples for fecal coliform bacteria levels, however, results are not available until at least 24 hours after sampling. To avoid the need for laboratory analyses, ordinary least squares (OLS) and logistic regression models were developed to predict fecal coliform bacteria concentrations and the probabilities of exceeding the Massachusetts secondary contact recreation standard for bacteria based on meteorological conditions and streamflow. The OLS models resulted in adjusted R2s ranging from 50 to 60 percent. An uncertainty analysis reveals that of the total variability of fecal coliform bacteria concentrations, 45 percent is explained by the OLS regression model, 15 percent is explained by both measurement and space sampling error, and 40 percent is explained by time sampling error. Higher accuracy in future bacteria forecasting models would likely result from reductions in laboratory measurement errors and improved sampling designs. 相似文献
655.
随着页岩气平台井工厂化压裂施工启动,在大排量、高压力、长时间施工条件下,高压管汇失效爆裂大幅增加。为减少高压管汇在压裂过程中失效爆裂风险,运用故障假设、因果分析法从人的因素、物的因素、技术工艺、生产管理、工作环境5个方面分析事故的原因,提出了提升采购产品质量、修订完善高压管汇使用技术规范和管理制度、实施专业化管理、应用大数据管理高压管汇、优化现场地面高压管汇流程分配布局设计与联接工艺等高压管汇失效爆裂风险预防控制措施和失效后应急安全防护措施,建立了生命周期全过程、专业化的高压管汇失效爆裂防控与应急防护体系,实现风险可防受控。为页岩气压裂作业的安全提供了参考。 相似文献
656.
657.
为分析“十三五”期间(2016—2020年)我国化工和危险化学品事故发生情况,统计“十三五”期间化工和危险化学品事故数量及死亡人数,从发生月份、发生区域、行业分布等方面分析事故特征,从事故类别、事故环节、关键作业等方面分析事故原因,总结2011—2020年我国化工和危险化学品事故发展趋势,按照全国4大经济区域研究2013—2020年事故特征。结果表明:“十三五”期间我国化工和危险化学品事故数量呈下降趋势,死亡人数出现波动,总体形势较为平稳。2011—2020年化工和危险化学品事故风险向中西部转移趋势明显,东北、西部地区事故死亡率普遍高于东部地区。研究结果可为相关行业从业者及监管部门提供决策参考。 相似文献
658.
E.V. Antonakou K.G. Kalogiannis S.D. Stephanidis K.S. Triantafyllidis A.A. Lappas D.S. Achilias 《Waste management (New York, N.Y.)》2014,34(12):2487-2493
Pyrolysis appears to be a promising recycling process since it could convert the disposed polymers to hydrocarbon based fuels or various useful chemicals. In the current study, two model polymers found in WEEEs, namely polycarbonate (PC) and high impact polystyrene (HIPS) and their counterparts found in waste commercial Compact Discs (CDs) were pyrolysed in a bench scale reactor. Both, thermal pyrolysis and pyrolysis in the presence of two catalytic materials (basic MgO and acidic ZSM-5 zeolite) was performed for all four types of polymers. Results have shown significant recovery of the monomers and valuable chemicals (phenols in the case of PC and aromatic hydrocarbons in the case of HIPS), while catalysts seem to decrease the selectivity towards the monomers and enhance the selectivity towards other desirable compounds. 相似文献
659.
Damon M. Hall Gerardo R. Camilo Rebecca K. Tonietto Jeff Ollerton Karin Ahrné Mike Arduser John S. Ascher Katherine C. R. Baldock Robert Fowler Gordon Frankie Dave Goulson Bengt Gunnarsson Mick E. Hanley Janet I. Jackson Gail Langellotto David Lowenstein Emily S. Minor Stacy M. Philpott Simon G. Potts Muzafar H. Sirohi Edward M. Spevak Graham N. Stone Caragh G. Threlfall 《Conservation biology》2017,31(1):24-29
Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high‐priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators’ relatively small functional requirements—habitat range, life cycle, and nesting behavior—relative to larger mammals, we argue that pollinators put high‐priority and high‐impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization. 相似文献
660.
Protected areas (PAs) and payments for ecosystem services (PES) are the top two mechanisms available for countries to achieve international REDD agreements, yet there are few empirical comparisons of their effects. We estimate the impacts of PAs and PES on forest conservation, poverty reduction, and population change at the locality level in Mexico in the 2000s. Both policies conserved forest, generating an approximately 20–25% reduction in expected forest cover loss. PES created statistically significant but small poverty alleviation while PAs had overall neutral impacts on livelihoods. Estimates by individual policy type for the same level of deforestation risk indicate that biosphere reserves and PES balanced conservation and livelihood goals better than strict protected areas or mixed-use areas. This suggests that both direct and incentive-based instruments can be effective, and that policies combining sustainable financing, flexible zoning, and recognition of local economic goals are more likely to achieve conservation without harming livelihoods. 相似文献