全文获取类型
收费全文 | 254篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 17篇 |
废物处理 | 4篇 |
环保管理 | 100篇 |
综合类 | 9篇 |
基础理论 | 57篇 |
污染及防治 | 41篇 |
评价与监测 | 14篇 |
社会与环境 | 14篇 |
灾害及防治 | 4篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 34篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 19篇 |
2006年 | 17篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 15 毫秒
251.
Cerveny LK Blahna DJ Stern MJ Mortimer MJ Predmore SA Freeman J 《Environmental management》2011,48(3):644-657
U.S. Forest Service managers are required to incorporate social and biophysical science information in planning and environmental
analysis. The use of science is mandated by the National Environmental Policy Act, the National Forest Management Act, and
U.S. Forest Service planning rules. Despite the agency’s emphasis on ‘science-based’ decision-making, little is known about
how science is actually used in recreation planning and management. This study investigated the perceptions of Forest Service
interdisciplinary (ID) team leaders for 106 NEPA projects dealing with recreation and travel management between 2005 and 2008.
Our survey data show how managers rate the importance of social and biophysical science compared to other potential ‘success
factors’ in NEPA assessments. We also explore how team leaders value and use multi-disciplinary tools for recreation-related
assessments. Results suggest that managers employ a variety of recreation planning tools in NEPA projects, but there appears
to be no common understanding or approach for how or when these tools are incorporated. The Recreation Opportunity Spectrum
(ROS) was the most frequently used planning tool, but the Visitor Experience and Resource Protection (VERP) framework was
the most consistently valued tool by those who used it. We recommend further evaluation of the strengths and weaknesses of
each planning tool and future development of procedures to select appropriate planning tools for use in recreation-related
NEPA assessments. 相似文献
252.
Doucet JJ Hill L Stout P Bansal V Lee J Fortlage D Potenza B Workman P Coimbra R 《Journal of Safety Research》2011,42(2):131-135
Objective
Pedicabs are a new and controversial transportation innovation for tourists in congested areas in several U.S. cities. Scant literature on this trauma mechanism exists. The purpose of this study is to identify the incidence, demographics, morbidity, mortality, and potential for injury prevention of pedicab incidents amongst major trauma admissions at an urban, academic Level I Trauma Center.Patients & Methods
Researchers conducted a retrospective review of the Trauma Registry from 2000 to 2009. All patients identified as being injured in a pedicab incident were reviewed. Demographics, diagnoses, toxicology, treatments, and injury severity scale (ISS) were collected. Outcomes included mortality, ICU, and hospital length of stay (LOS), discharge disposition, and hospital charges. A photographic survey of 50 local pedicabs was examined for the presence and use of safety equipment.Results
During the period of January 2000 to July 2009 there were 15 major trauma victims from identified pedicab incidents. Falling from the pedicab was the mechanism of injury in 14 of 15 cases. There were two fatalities in victims following severe traumatic brain injury. Traumatic brain injury, skull fracture, or loss of consciousness was seen in 11/15 victims. Ethanol ingestion was detected in blood tests of 10 of the 14 adult victims. Median charges of hospitalization due to a pedicab related injury was US$29,956 ± 77,482. A photographic survey of 50 local pedicabs reveals very limited use of safety belts by passengers despite existing city ordinances.Conclusions
Major trauma victims of pedicab incidents in the United States suffer significant injuries and death. Most cases occurred in passengers falling from the pedicab at night after alcohol ingestion. There is an opportunity for implementation of strategies toward improved injury prevention with this new form of transport. 相似文献253.
Abstract In this paper we question the importance of social capital as a primary indicator of a community's ability to engage in sustainable development as social capital can have both hindering and facilitating effects. We suggest that actor agency allows an individual or group to increase access to other critical forms of capital to overcome barriers and solve problems. We present ‘bonding’ social capital consisting of strong network ties as a negative in excess quantity as it can lead to the enforcement of social norms that hinder innovative change, and ‘bridging’ social capital consisting of weak network ties as a benefit that allows actors to bring about critical social changes. Communities achieve agency through a dynamic mix of bonding and bridging ties. We close with suggestions for fostering community agency and flag the need for further research in this area. 相似文献
254.
Radioactive particles present a novel exposure pathway for members of the public. For typical assessments of potential doses received by members of the public, habit surveys and environmental monitoring combine to allow the assessment to occur. In these circumstances it is believed that the probability of encounter/consumption is certain. The potential detriment is assessed through sampling the use of environmental monitoring data and dose coefficients such as that in ICRP 60 [ICRP, 1990. 1990 Recommendations of the international commission on radiological protection. Publication 60. Annals of the ICRP 21 (1-3)]. However, radioactive particles often represent a hazard that is difficult to quantify and where the probability of encounter is less than certain as are the potential effects on health. Normal assessment methodologies through sampling and analysis are not appropriate for assessing the impact of radioactive particles either prospectively or retrospectively. This paper details many of the issues that should be considered when undertaking an assessment of the risk to health posed by radioactive particles. 相似文献
255.
256.
Progressive N limitation in forests: review and implications for long-term responses to elevated CO2
Johnson DW 《Ecology》2006,87(1):64-75
Field studies have shown that elevated CO2 can cause increased forest growth over the short term (<6 years) even in the face of N limitation. This is facilitated to some degree by greater biomass production per unit N uptake (lower tissue N concentrations), but more often than not, N uptake is increased with elevated CO2 as well. Some studies also show that N sequestration in the forest floor is increased with elevated CO2. These findings raise the questions of where the "extra" N comes from and how long such growth increases can continue without being truncated by progressive N limitation (PNL). This paper reviews some of the early nutrient cycling literature that describes PNL during forest stand development and attempts to use this information, along with recent developments in soil N research, to put the issue of PNL with elevated CO2 into perspective. Some of the early studies indicated that trees can effectively "mine" N from soils over the long term, and more recent developments in soil N cycling research suggest mechanisms by which this might have occurred. However, both the early nutrient cycling literature and more recent simulation modeling suggest that PNL will at some point truncate the observed increases in growth and nutrient uptake with elevated CO2, unless external inputs of N are increased by either N fixation or atmospheric deposition. 相似文献
257.
Salzar RS Bass CR Kent R Millington S Davis M Lucas S Rudd R Folk B Donnellan L Murakami D Kobayashi S 《Traffic injury prevention》2006,7(3):299-305
OBJECTIVE: This article assesses the position-dependent injury tolerance of the hip in the frontal direction based on testing of eight postmortem human subjects. METHODS: For each subject, the left and right hemipelvis complex was axially loaded using a previously developed test configuration. Six positions were defined from a seated femur neutral condition, combining flexed, neutral, and extended femur positions with abducted, neutral, and adducted positions. RESULTS: Axial injury tolerances based on peak force were found to be 6,850 +/- 840 N in the extended, neutral position and 4,080 +/- 830 N in the flexed, neutral position. From the flexed neutral orientation, the peak axial force increased 18% for 20 degrees abduction and decreased 6% for 20 degrees adduction. From the extended, neutral orientation, the peak axial force decreased 4% for 20 degrees abduction and decreased 3% for 20 degrees adduction. However, as there is evidence that increases in loading may occur after the initiation of fracture, the magnitude of the peak force is likely related to the extent of injury, not to the initial tolerance. Using the axial femur force at the initiation of fracture (assessed with acoustic crack sensors) as a potentially more relevant indicator of injury may lower the existing injury criteria. This fracture initiation force varied by position from 3,010 +/- 560 N in the flexed, neutral position to 5,470 N in the extended, abducted position. Further, there was a large position-dependent variation in the ratio of fracture initiation force to the peak axial force. The initiation of fracture was 83% of the peak axial force in the extended, abducted position, but the ratio was 34% in the extended, adducted position. CONCLUSIONS: This may have significant implications for the development of pelvic injury criteria by automobile designers attempting to mitigate pelvis injuries. 相似文献
258.
This study aimed to determine the extent to which older drivers can be considered responsible for their crashes, to identify key factors in those crashes for which older drivers have been judged responsible, and to assess the extent to which older drivers' extra crash responsibility contributes to the road toll. Insurance claims from the State of Tasmania, Australia, for 1998-2002 were linked with police records for crashes involving drivers aged either 41-55 years or 65 years or older. Insurance and police data sets contained independent judgments of crash responsibility. There was a high level of agreement between the two sets of judgments, with older drivers judged around 1.5 times more likely to be responsible for their crashes than middle-aged drivers and, conversely, older drivers were around 0.6 as likely to be absolved from crash responsibility. It was concluded that older drivers' additional crash responsibility while valuable in explaining "what went wrong," currently makes only a small contribution to the overall road toll. 相似文献
259.
We sampled 41 sites on 34 nonwadeable rivers that represent the types of rivers in Wisconsin, and the kinds and intensities
of nutrient and other anthropogenic stressors upon each river type. Sites covered much of United States Environmental Protection
Agency national nutrient ecoregions VII—Mostly Glaciated Dairy Region, and VIII—Nutrient Poor, Largely Glaciated upper Midwest.
Fish, macroinvertebrates, and three categories of environmental variables including nutrients, other water chemistry, and
watershed features were collected using standard protocols. We summarized fish assemblages by index of biotic integrity (IBI)
and its 10 component measures, and macroinvertebrates by 2 organic pollution tolerance and 12 proportional richness measures.
All biotic and environmental variables represented a wide range of conditions, with biotic measures ranging from poor to excellent
status, despite nutrient concentrations being consistently higher than reference concentrations reported for the regions.
Regression tree analyses of nutrients on a suite of biotic measures identified breakpoints in total phosphorus (~0.06 mg/l)
and total nitrogen (~0.64 mg/l) concentrations at which biotic assemblages were consistently impaired. Redundancy analyses
(RDA) were used to identify the most important variables within each of the three environmental variable categories, which
were then used to determine the relative influence of each variable category on the biota. Nutrient measures, suspended chlorophyll
a, water clarity, and watershed land cover type (forest or row-crop agriculture) were the most important variables and they
explained significant amounts of variation within the macroinvertebrate (R
2
= 60.6%) and fish (R
2
= 43.6%) assemblages. The environmental variables selected in the macroinvertebrate model were correlated to such an extent
that partial RDA analyses could not attribute variation explained to individual environmental categories, assigning 89% of
the explained variation to interactions among the categories. In contrast, partial RDA attributed much of the explained variation
to the nutrient (25%) and other water chemistry (38%) categories for the fish model. Our analyses suggest that it would be
beneficial to develop criteria based upon a suite of biotic and nutrient variables simultaneously to deem waters as not meeting
their designated uses. 相似文献
260.
Hungate BA Johnson DW Dijkstra P Hymus G Stiling P Megonigal JP Pagel AL Moan JL Day F Li J Hinkle CR Drake BG 《Ecology》2006,87(1):26-40
Experimentally increasing atmospheric CO2 often stimulates plant growth and ecosystem carbon (C) uptake. Biogeochemical theory predicts that these initial responses will immobilize nitrogen (N) in plant biomass and soil organic matter, causing N availability to plants to decline, and reducing the long-term CO2-stimulation of C storage in N limited ecosystems. While many experiments have examined changes in N cycling in response to elevated CO2, empirical tests of this theoretical prediction are scarce. During seven years of postfire recovery in a scrub oak ecosystem, elevated CO2 initially increased plant N accumulation and plant uptake of tracer 15N, peaking after four years of CO2 enrichment. Between years four and seven, these responses to CO2 declined. Elevated CO2 also increased N and tracer 15N accumulation in the O horizon, and reduced 15N recovery in underlying mineral soil. These responses are consistent with progressive N limitation: the initial CO2 stimulation of plant growth immobilized N in plant biomass and in the O horizon, progressively reducing N availability to plants. Litterfall production (one measure of aboveground primary productivity) increased initially in response to elevated CO2, but the CO2 stimulation declined during years five through seven, concurrent with the accumulation of N in the O horizon and the apparent restriction of plant N availability. Yet, at the level of aboveground plant biomass (estimated by allometry), progressive N limitation was less apparent, initially because of increased N acquisition from soil and later because of reduced N concentration in biomass as N availability declined. Over this seven-year period, elevated CO2 caused a redistribution of N within the ecosystem, from mineral soils, to plants, to surface organic matter. In N limited ecosystems, such changes in N cycling are likely to reduce the response of plant production to elevated CO2. 相似文献