全文获取类型
收费全文 | 2073篇 |
免费 | 37篇 |
国内免费 | 54篇 |
专业分类
安全科学 | 76篇 |
废物处理 | 105篇 |
环保管理 | 301篇 |
综合类 | 328篇 |
基础理论 | 559篇 |
环境理论 | 1篇 |
污染及防治 | 510篇 |
评价与监测 | 134篇 |
社会与环境 | 134篇 |
灾害及防治 | 16篇 |
出版年
2023年 | 18篇 |
2022年 | 62篇 |
2021年 | 22篇 |
2020年 | 29篇 |
2019年 | 32篇 |
2018年 | 75篇 |
2017年 | 59篇 |
2016年 | 52篇 |
2015年 | 72篇 |
2014年 | 64篇 |
2013年 | 165篇 |
2012年 | 77篇 |
2011年 | 110篇 |
2010年 | 100篇 |
2009年 | 103篇 |
2008年 | 104篇 |
2007年 | 99篇 |
2006年 | 73篇 |
2005年 | 64篇 |
2004年 | 96篇 |
2003年 | 85篇 |
2002年 | 61篇 |
2001年 | 111篇 |
2000年 | 50篇 |
1999年 | 34篇 |
1998年 | 25篇 |
1997年 | 22篇 |
1996年 | 12篇 |
1995年 | 27篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 19篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 12篇 |
1971年 | 6篇 |
1959年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有2164条查询结果,搜索用时 203 毫秒
991.
992.
The populations of many North American landbirds are showing signs of declining. Gathering information on breeding productivity
allows critical assessment of population performance and helps identify good habitat-management practices. He (Biometrics
(2003) 59 962–973) proposed a Bayesian model to estimate the age-specific nest survival rates. The model allows irregular
visiting schedule under the assumption that the observed nests have homogeneous nest survival. Because nest survival studies
are often conducted in different sites and time periods, it is not realistic to assume homogeneous nest survival. In this
paper, we extend He’s model by incorporating these factors as categorical covariates. The simulation results show that the
Bayesian hierarchical model can produce satisfactory estimates on nest survival and capture different factor effects. Finally
the model is applied to a Missouri red-winged blackbird data set. 相似文献
993.
994.
Adapting to Climate Change on Western Public Lands: Addressing the Ecological Effects of Domestic, Wild, and Feral Ungulates 总被引:2,自引:2,他引:0
Robert L. Beschta Debra L. Donahue Dominick A. DellaSala Jonathan J. Rhodes James R. Karr Mary H. O’Brien Thomas L. Fleischner Cindy Deacon Williams 《Environmental management》2013,51(2):474-491
Climate change affects public land ecosystems and services throughout the American West and these effects are projected to intensify. Even if greenhouse gas emissions are reduced, adaptation strategies for public lands are needed to reduce anthropogenic stressors of terrestrial and aquatic ecosystems and to help native species and ecosystems survive in an altered environment. Historical and contemporary livestock production—the most widespread and long-running commercial use of public lands—can alter vegetation, soils, hydrology, and wildlife species composition and abundances in ways that exacerbate the effects of climate change on these resources. Excess abundance of native ungulates (e.g., deer or elk) and feral horses and burros add to these impacts. Although many of these consequences have been studied for decades, the ongoing and impending effects of ungulates in a changing climate require new management strategies for limiting their threats to the long-term supply of ecosystem services on public lands. Removing or reducing livestock across large areas of public land would alleviate a widely recognized and long-term stressor and make these lands less susceptible to the effects of climate change. Where livestock use continues, or where significant densities of wild or feral ungulates occur, management should carefully document the ecological, social, and economic consequences (both costs and benefits) to better ensure management that minimizes ungulate impacts to plant and animal communities, soils, and water resources. Reestablishing apex predators in large, contiguous areas of public land may help mitigate any adverse ecological effects of wild ungulates. 相似文献
995.
S.Z. Cohen 《Journal of environmental science and health. Part. B》2013,48(3):345-352
Abstract Scientific and regulatory interest in ground water contamination by pesticides increased significantly in 1979. This was prompted by findings of the nematicide 1,2‐dibromo‐3‐chloropropane (DBCP) and the nematicide/insecticide aldicarb (Temik®) in ground water in several states. Since that time, at least 130 pesticides and pesticide metabolites have been detected in ground water in over 150 studies, but detection frequencies are 4–10% nationally. Detection frequencies of pesticides over Health Advisory Levels are generally lower. Screening‐level models and detailed computer simulation models are useful for risk assessments and regulatory decisions. Attenuation Factor, CMLS, PRZM2, GLEAMS, and LEACHM are all useful models. 相似文献
996.
Cheryl M. E. McCrindle Marianna Siegmund-Schultze Alexander W. Heeb Anne Valle Zárate Shashi Ramrajh 《Environment, Development and Sustainability》2013,15(5):1245-1257
Game harvesting in South Africa generally leaves behind edible by-products, which could be a low-cost source of protein for poor people in rural areas. Seven professional and nine recreational hunters were interviewed, a game harvest and trophy hunt attended and literature reviewed, in order to describe the food value chain for game and ways in which edible by-products could be legally channelled into the human food chain, rather than being left in the field for scavengers. Practices of informal vendors (n = 51) were assessed using structured interviews, observation and microbiological analysis. In an experiment, inspected game by-products (shinbones from impala and springbok) were provided to eight informal traders for cooking at an informal market and microbiological analysis was done before and after preparation. The results showed that providing edible by-products to poor consumers appears to be culturally acceptable, affordable, accessible and safe. A crossover from formal to informal marketing is recommended as it would enhance traceability and safety of the product and minimise the risk of poaching. It is suggested that methods should be developed which make the distribution of edible by-products to vulnerable rural communities feasible. 相似文献
997.
Dimitrios Zekkos George A. Athanasopoulos Jonathan D. Bray Athena Grizi Andreas Theodoratos 《Waste management (New York, N.Y.)》2010,30(8-9):1544-1555
Large direct shear testing (300 mm × 300 mm box) of municipal solid waste (MSW) collected from a landfill located in the San Francisco Bay area was performed to gain insight on the shear response of MSW. The study investigated the effects of waste composition, confining stress, unit weight, and loading rate on the stress–displacement response and shear strength of MSW. The amount and orientation of the fibrous waste materials in the MSW were found to play a critical role. The fibrous material had little effect on the MSW’s strength when it was oriented parallel to the shear surface, as is typically the case when waste material is compressed vertically and then tested in a direct shear apparatus. Tests in which the fibrous material was oriented perpendicular to the horizontal shear surface produced significantly stronger MSW specimens. The test results indicate that confining stress and loading rate are also important factors. Based on 109 large-scale direct shear tests, the shear strength of MSW at low moisture contents is best characterized by cohesion = 15 kPa, friction angle = 36° at a normal stress of 1 atmosphere, and a decrease in the friction angle of 5° for every log-cycle increase in normal stress. 相似文献
998.
Sebastian Theis Jonathan L.W. Ruppert Karling N. Roberts Charles K. Minns Marten Koops Mark S. Poesch 《Conservation biology》2020,34(1):41-53
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes. 相似文献
999.
K. Lebecki J.
li K. Cybulski Z. Dyduch 《Journal of Loss Prevention in the Process Industries》2001,14(6):489-494
The paper describes large-scale tests of triggered barriers of different design. Main stress was put on examining suitability of the flame detector developed in US Bureau of Mines to work as a trigger for the barriers. It was found that the detector works satisfactorily with the barriers of different design providing a suitable mean to suppress explosions in galleries, either in mines or in other industries. 相似文献
1000.
This study uses DAYCENT model to investigate the sensitivity of soil organic carbon (SOC) at an intensely cultivated site in the U.S. Midwest under an ensemble of scenario climates predicted by IPCC models. The model ensemble includes three IPCC models (Canadian, French, German), three emission scenarios (B1, A1B, A2) and three time periods (late 20th, mid-21st, late 21st century). DAYCENT shows that SOC at the site would decline by 0.3-2.6 kg m−2 (5-35%) depending on the models and scenarios from late 20th to mid-21st century despite a larger increase of future net primary production (NPP) than respiration. The future SOC decrease is mostly attributable to harvest loss. The wide spread in future SOC decline rates are in part because SOC decrease (by respiration) is directly proportional to SOC itself. Any uncertainty in absolute SOC in DAYCENT would translate directly into its trend, unlike other variables such as temperature whose trends are independent of their values themselves, contrasting the reliability of SOC trend with temperature change. 相似文献