全文获取类型
收费全文 | 561篇 |
免费 | 9篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 28篇 |
废物处理 | 23篇 |
环保管理 | 87篇 |
综合类 | 110篇 |
基础理论 | 123篇 |
环境理论 | 1篇 |
污染及防治 | 143篇 |
评价与监测 | 45篇 |
社会与环境 | 15篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 27篇 |
2013年 | 47篇 |
2012年 | 24篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 28篇 |
2008年 | 38篇 |
2007年 | 26篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 18篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1983年 | 3篇 |
1967年 | 2篇 |
1963年 | 3篇 |
1962年 | 3篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1959年 | 3篇 |
1956年 | 3篇 |
1954年 | 3篇 |
1946年 | 2篇 |
1930年 | 1篇 |
1929年 | 1篇 |
1926年 | 2篇 |
1924年 | 1篇 |
1921年 | 1篇 |
1916年 | 3篇 |
1915年 | 1篇 |
排序方式: 共有578条查询结果,搜索用时 17 毫秒
61.
62.
Nina Rønsted Seana K. Walsh Margaret Clark Merlin Edmonds Tim Flynn Scott Heintzman Alexander Loomis David Lorence Uma Nagendra Ben Nyberg Michael Opgenorth Lauren Weisenberger Adam Williams Dustin Wolkis Kenneth R. Wood Matthew Keir 《Conservation biology》2022,36(4):e13896
The International Union for Conservation of Nature's Red List of Threatened Species (IUCN Red List) is the world's most comprehensive information source on the global conservation status of species. Governmental agencies and conservation organizations increasingly rely on IUCN Red List assessments to develop conservation policies and priorities. Funding agencies use the assessments as evaluation criteria, and researchers use meta-analysis of red-list data to address fundamental and applied conservation science questions. However, the circa 143,000 IUCN assessments represent a fraction of the world's biodiversity and are biased in regional and organismal coverage. These biases may affect conservation priorities, funding, and uses of these data to understand global patterns. Isolated oceanic islands are characterized by high endemicity, but the unique biodiversity of many islands is experiencing high extinction rates. The archipelago of Hawaii has one of the highest levels of endemism of any floristic region; 90% of its 1367 native vascular plant taxa are classified as endemic. We used the IUCN's assessment of the complete single-island endemic (SIE) vascular plant flora of Kauai, Hawaii, to assess the proportion and drivers of decline of threatened plants in an oceanic island setting. We compared the IUCN assessments with federal, state, and other local assessments of Kauai species or taxa of conservation concern. Finally, we conducted a preliminary assessment for all 1044 native vascular plants of Hawaii based on IUCN criterion B by estimating area of occupancy, extent of occurrence, and number of locations to determine whether the pattern found for the SIE vascular flora of Kauai is comparable to the native vascular flora of the Hawaiian Islands. We compared our results with patterns observed for assessments of other floras. According to IUCN, 256 SIE vascular plant taxa are threatened with extinction and 5% are already extinct. This is the highest extinction risk reported for any flora to date. The preliminary assessment of the native vascular flora of Hawaii showed that 72% (753 taxa) is threatened. The flora of Hawaii may be one of the world's most threatened; thus, increased and novel conservation measures in the state and on other remote oceanic islands are urgently needed. 相似文献
63.
The concentrations of heavy metals (Cd, Cu, Ni, Pb, Zn and Mn) and macroelements (K, Na, Ca and Mg) were determined in green alga Enteromorpha sp. from the coastal zone of the southern Baltic including Gulf of Gdańsk and Vistula Lagoon in 2000-2003. In order to estimate the degree of accumulation of each element by the green alga, concentration and discrimination factors (CFs) with respect to seawater were calculated. The results of factor analysis (FA) and ANOVA clearly indicate geographical differences between concentrations of chemical elements. Enteromorpha sp. from Vistula Lagoon and the southern Baltic exhibited higher levels of Mn and Ni, and Na and K, respectively. Anthropogenic impact of Cu, Pb and Zn, possibly originated from municipal sewage, was identified in alga samples collected in the Gulf of Gdańsk, especially in the vicinity of Gdynia. From comparison our data with those published earlier results that Pb content in Enteromorpha sp. from the Gulf of Gdańsk decreased within 1978-2003 reflecting reducing use of leaded petrol in Baltic countries in this period. The alga Enteromorpha sp. can be used for biomonitoring surveys of metal contaminants in coastal areas of the Baltic Sea. 相似文献
64.
Pawlaczyk-?uszczyńska M Dudarewicz A Zamojska M Sliwinska-Kowalska M 《International journal of occupational safety and ergonomics》2012,18(2):279-296
Noise measurements and questionnaire inquiries were carried out for 124 workers of a rolling stock plant to develop a hearing conservation program. On the basis of that data, the risk of noise-induced hearing loss (NIHL) was evaluated. Additionally, the workers' hearing ability was assessed with the (modified) Amsterdam inventory for auditory disability and handicap, (m)AIADH. The workers had been exposed to noise at A-weighted daily noise exposure levels of 74-110 dB for 1-40 years. Almost one third of the workers complained of hearing impairment and the (m)AIADH results showed some hearing difficulties in over half of them. The estimated risk of hearing loss over 25 dB in the frequency range of 3-6 kHz was 41-50% when the standard method of predicting NIHL specified in Standard No. ISO 1999:1990 was used. This risk increased to 50-67% when noise impulsiveness, coexposure to organic solvents, elevated blood pressure and smoking were included in calculations. 相似文献
65.
66.
Adam Erickson 《Ambio》2015,44(5):343-352
New institutions are critically needed to improve the resilience of social–ecological systems globally. Watershed management offers an important model due to its ability to govern mixed-ownership landscapes through common property regimes, translating national goals into local action. Here, I assess the efficacy of state watershed management institutions in the Pacific Northwest, based on their ability to support local watershed groups. I use document analysis to describe and compare state institutions in Washington, Oregon, Idaho, and California. Results indicate that state institutional efficiency and resilience are the key factors determining watershed group activity and stability. The primary drivers of institutional efficiency and resilience were institutional unification, robust funding portfolios, low agency conflict, and strong support for economic multiplier effects, creative partnerships, and scholarly research. My findings elucidate the critical role of institutional efficiency and resilience in governing dynamic and complex social–ecological systems, enabling the flexibility to address emergent transformations. 相似文献
67.
Lucy Rist Adam Felton Erland Mårald Lars Samuelsson Tomas Lundmark Ola Rosvall 《Ambio》2016,45(2):140-151
There is a growing demand for alternatives to Sweden’s current dominant silvicultural system, driven by a desire to raise biomass production, meet environmental goals and mitigate climate change. However, moving towards diversified forest management that deviates from well established silvicultural practices carries many uncertainties and risks. Adaptive management is often suggested as an effective means of managing in the context of such complexities. Yet there has been scepticism over its appropriateness in cases characterised by large spatial extents, extended temporal scales and complex land ownership—characteristics typical of Swedish forestry. Drawing on published research, including a new paradigm for adaptive management, we indicate how common pitfalls can be avoided during implementation. We indicate the investment, infrastructure, and considerations necessary to benefit from adaptive management. In doing so, we show how this approach could offer a pragmatic operational model for managing the uncertainties, risks and obstacles associated with new silvicultural systems and the challenges facing Swedish forestry. 相似文献
68.
Significant ecological, hydrologic, and geomorphic changes have occurred during the 20th century along many large floodplain rivers in the American Southwest. Native Populus forests have declined, while the exotic Eurasian shrub, Tamarix, has proliferated and now dominates most floodplain ecosystems. Photographs from late 19th and early 20th centuries illustrate wide river channels with largely bare in-channel landforms and shrubby higher channel margin floodplains. However, by the mid-20th century, floodplains supporting dense Tamarix stands had expanded, and river channels had narrowed. Along the lower Green River in eastern Utah, the causal mechanism of channel and floodplain changes remains ambiguous due to the confounding effects of climatically driven reductions in flood magnitude, river regulation by Flaming Gorge Dam, and Tamarix invasion. This study addressed whether Tamarix establishment and spread followed climate- or dam-induced reductions in annual peak flows or whether Tamarix was potentially a driver of floodplain changes. We aged 235 Tamarix and 57 Populus individuals, determined the hydrologic and geomorphic processes that controlled recruitment, identified the spatial relationships of germination sites within floodplain stratigraphic transects, and mapped woody riparian vegetation cohorts along three segments of the lower Green River. The oldest Tamarix established along several sampling reaches in 1938, and 1.50-2.25 m of alluvium has accreted above their germination surfaces. Nearly 90% of the Tamarix and Populus samples established during flood years that exceeded the 2.5-year recurrence interval. Recruitment was most common when large floods were followed by years with smaller peak flows. The majority of Tamarix establishment and Green River channel narrowing occurred long before river regulation by Flaming Gorge Dam. Tamarix initially colonized bare instream sand deposits (e.g., islands and bars), and most channel and floodplain changes followed the establishment of Tamarix. Our results suggest that Tamarix recruitment was triggered by large annual floods that were followed by years with lower peak flows, not by periods of low flow alone. Tamarix appears to have actively invaded floodplains, while Populus colonization has been limited. Thus, Tamarix invasion may have greatly influenced floodplain development and riparian vegetation composition along the lower Green River since the early 20th century. 相似文献
69.
Adam R. Smith William T. Wcislo Sean O’Donnell 《Behavioral ecology and sociobiology》2007,61(7):1111-1120
Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively
social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks
in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on
one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did
social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests
had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests.
After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions
of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures,
M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from
collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate
of solitary nest productivity. 相似文献
70.
The present study describes the emergence pattern of loggerhead sea turtle hatchlings (Caretta caretta) from a nesting beach in Kyparissia Bay (Greece). We try to establish the role played by hatchling biometry, nest relocation
and distance from nest to the sea on this emergence pattern. We surveyed a total of 32 nests, and found long emergence periods
(mean = 6.7 nights). The majority of emergences occurred at night, mainly between 0030 and 0100 hours, and in small groups.
Most of the hatchlings emerged from the nests the first night. We found no clear trend when we studied the effect of hatchling
biometry between successive emergence days. We also found that relocation of the nests did not significantly affect the emergence
pattern. However, we noted that in the relocated nests, hatchlings emerged in smaller groups. Emergence periods were inversely
related to distance from the sea. In short, factors such as climate conditions, relocation and nest distance to the sea appear
to have some effect on the emergence pattern. Therefore, they should be taken into account in both biological studies and
management plans for sea turtle nesting beaches. Our results suggest leaving an extended period between the first emergence
of hatchlings and the excavation of nests by researchers in future studies in the area. 相似文献