全文获取类型
收费全文 | 1661篇 |
免费 | 31篇 |
国内免费 | 19篇 |
专业分类
安全科学 | 61篇 |
废物处理 | 61篇 |
环保管理 | 254篇 |
综合类 | 310篇 |
基础理论 | 375篇 |
环境理论 | 2篇 |
污染及防治 | 412篇 |
评价与监测 | 136篇 |
社会与环境 | 93篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 23篇 |
2022年 | 33篇 |
2021年 | 32篇 |
2020年 | 23篇 |
2019年 | 24篇 |
2018年 | 41篇 |
2017年 | 38篇 |
2016年 | 51篇 |
2015年 | 44篇 |
2014年 | 52篇 |
2013年 | 90篇 |
2012年 | 73篇 |
2011年 | 98篇 |
2010年 | 66篇 |
2009年 | 84篇 |
2008年 | 78篇 |
2007年 | 104篇 |
2006年 | 81篇 |
2005年 | 63篇 |
2004年 | 72篇 |
2003年 | 56篇 |
2002年 | 52篇 |
2001年 | 41篇 |
2000年 | 25篇 |
1999年 | 20篇 |
1998年 | 31篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 21篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1972年 | 4篇 |
1968年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有1711条查询结果,搜索用时 15 毫秒
151.
152.
153.
Abstract: Illegal exploitation threatens the survival of many species, and anti-poaching legislation ("protection on paper") does not protect species. State enforcement is needed to support and supplement the formal status of endangered species, but state enforcement can be a source of instability leading to the demise of species if ad hoc rules are followed blindly. We demonstrate this with a model of poaching, wildlife, and government wildlife enforcement, but our findings apply more generally. Crucial assumptions of the dynamic model are that both poaching and enforcement effort increase or decrease whenever poaching effort and enforcement are relatively profitable or unprofitable activities, respectively. We found that multiple steady states may characterize the system's equilibrium. Depending on initial populations, the initial extent of state involvement, and random events, animal populations may be severely depleted or unexpectedly built up during transition phases. Our findings highlight the importance of history and luck in protecting endangered species. 相似文献
154.
155.
Intrauterine fetal growth restriction (IUGR) is an important pregnancy complication associated with significant adverse clinical outcome, stillbirth, perinatal morbidity and cerebral palsy. To date, no uniformly accepted management protocol of Doppler surveillance that reduces mortality and cognitive morbidity has emerged. Aortic isthmus (AoI) evaluation has been proposed as a potential monitoring tool for IUGR fetuses. In this review, the current knowledge of the relationship between AoI Doppler velocimetry and preterm fetal growth restriction is reviewed. Relevant technical aspects and reproducibility data are reviewed as we discuss AoI Doppler and its place within the existing repertoire of Doppler assessments in placental insufficiency. The AoI is a link between the right and left ventricles which perfuse the lower and upper body, respectively. The clinical use of AoI waveforms for monitoring fetal deterioration in IUGR has been limited, but preliminary work suggests that abnormal AoI impedance indices are an intermediate step between placental insufficiency-hypoxemia and cardiac decompensation. Further prospective studies correlating AoI indices with arterial and venous Doppler indices and perinatal outcome are required before encorporating this index into clinical practice. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
156.
157.
158.
J. Van Caneghem C. Block P. Cramm R. Mortier C. Vandecasteele 《Journal of Cleaner Production》2010,18(8):807-814
In addition to CO2 released by the combustion of fossil fuel and leading to climate change, large steelworks emit pollutants that have other environmental impacts. ArcelorMittal Gent, an integrated steelwork producing ca. 5 × 106 tons of steel per year, not only decreased its specific energy consumption and CO2-emissions, but also reduced the environmental impact of its other emissions. This is illustrated by means of the evolution of 6 partial eco-efficiency indicators for the impact categories acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity, eutrophication and water use. The partial eco-efficiency indicators are eco-intensities, defined as the environmental impact in the respective impact category, divided by the amount of liquid steel produced. In the period 1995 – 2005 these indicators decreased by 45, 4, 52, 9, 11 and 33% respectively, whereas the steel production increased by 17%. The net impact of discharges of wastewater is negligible for human toxicity and is negative (concentrations lower than in the canal water used) for freshwater aquatic toxicity and eutrophication. For acidification, human toxicity (only emissions to air) and water use, the decoupling between environmental impact and production was absolute; for photo-oxidant formation, freshwater aquatic ecotoxicity (only emissions to air) and eutrophication, it was relative. 相似文献
159.
Stuart J. Marsden 《Conservation biology》1998,12(3):605-611
160.