全文获取类型
收费全文 | 74篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 8篇 |
环保管理 | 23篇 |
综合类 | 5篇 |
基础理论 | 20篇 |
污染及防治 | 4篇 |
评价与监测 | 8篇 |
社会与环境 | 3篇 |
灾害及防治 | 8篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有79条查询结果,搜索用时 187 毫秒
71.
Distribution and abundance of western gray whales off northeastern Sakhalin Island, Russia, 2001’003
Meier SK Yazvenko SB Blokhin SA Wainwright P Maminov MK Yakovlev YM Newcomer MW 《Environmental monitoring and assessment》2007,134(1-3):107-136
In 2001–2003, >60,000 km of aerial surveys and 7,700 km of vessel surveys were conducted during June to November when critically
endangered Korean–Okhotsk or western gray whales (Eschrichtius robustus) were present off the northeast coast of Sakhalin Island, Russia. Results of surveys in all years indicated gray whales occurred
in predominantly two areas, (1) adjacent to Piltun Bay, and (2) offshore from Chayvo Bay, hereafter referred to as the Piltun
and offshore feeding areas. In the Piltun feeding area, the majority of whales were observed in waters shallower than 20 m
and were distributed from several hundred meters to ∼ 5 km from the shoreline. In the offshore feeding area during all years,
the distribution of gray whales extended from southwest to northeast in waters 30–65 m in depth. During all years, the distribution
and abundance of whales changed in both the Piltun and offshore feeding areas, and both north–south and inshore–offshore movements
were documented within and between feeding seasons. The discovery of a significant number of whales feeding in the offshore
area each year was a substantial finding of this study and raises questions regarding western gray whale abundance and population
levels, feeding behavior and ecology, and individual site-fidelity. Fluctuations in the number of whales observed within the
Piltun and offshore feeding areas and few sightings outside of these two areas indicate that gray whales move between the
Piltun and offshore feeding areas during their summer–fall feeding season. Seasonal shifts in the distribution and abundance
of gray whales between and within both the Piltun and offshore feeding areas are thought, in part, to be a response to seasonal
changes in the distribution and abundance of prey. However, the mechanism driving the movements of whales along the northeast
coast of Sakhalin Island is likely very complex and influenced by a multitude of factors.
*Deceased 相似文献
72.
Elaine J. Brough Bruce Frank Frank Page Stewart Lindsay 《Agriculture, ecosystems & environment》1996,60(2-3)
An interdisciplinary team introduced Integrated Mite Control (IMC) to the Queensland apple industry in Australia from 1989 to 1992. Project funding supported the employment of a consultant to monitor mite levels and provide management advice to growers who paid for the service. Interviews at the beginning and end of the project showed widespread adoption of IMC over this period. Overall use of chemicals was not reduced, but the use pattern changed towards wider use of chemicals that are less toxic to predatory mites. The future of IMC in the Queensland apple industry is in doubt because the seasonal nature of apple production does not allow the paid consultancy service to be self-sustaining. Indications are that the integrated approach to pest management may not be generally accepted as a strategic management process while the availability of effective chemicals allows the continuation of a spray routine for mite control. The lack of availability of effective and proven methods of pest control was seen by growers as the major constraint to adoption of IMC. 相似文献
73.
The factor of scale in ecosystem mapping 总被引:2,自引:0,他引:2
Robert G. Bailey 《Environmental management》1985,9(4):271-275
74.
Thomas J. Myers Sherman Swanson 《Journal of the American Water Resources Association》1997,33(3):647-659
ABSTRACT: The precision of width and pool area measurements has rarely been considered in relation to downstream or at section hydraulic geometry, fisheries studies, long-term or along a continuum research studies, or agency monitoring techniques. We assessed this precision and related it to other stream morphologic characteristics. Confidence limits (95 percent) around mean estimates with four transects (cross-sections perpendicular to the channel center-line) ranged from ± 0.4 to 1.8 m on streams with a width of only 2.2 m. To avoid autocorrelation, transects should be spaced about three channel widths apart. To avoid stochastic inhomogeneity, reach length should be about 30 channel widths or ten transects to optimize sampling efficiency. Precision of width measurements decreased with decreased depth and increased with stream size. Both observations reflect variability caused by features such as boulders or coarse woody debris. Pool area precision increased with pool area reflecting increased precision for flat, wide streams with regular pool-rime sequences. The least precision occurred on small, steep streams with random, boulder or coarse woody debris formed pools. 相似文献
75.
Thomas J. Stohlgren Geneva W. Chong Mohammed a. Kalkhan Lisa D. Schell 《Environmental monitoring and assessment》1997,48(1):25-43
We present a rapid, cost-efficient methodology to link plantdiversity surveys from plots to landscapes using: (1) unbiasedsite selection based on remotely sensed information; (2) multi-scale field techniques to assess plant diversity; (3)mathematical models (species-area curves) to estimate thenumber of species in larger areas corrected for within-typeheterogeneity; and (4) mathematical techniques to estimatetotal species richness and patterns of plant diversity in alandscape. We demonstrate the methodology in a 754 ha studyarea in Rocky Mountain National Park, Colorado, U.S.A.,using four 0.025 ha and twenty-one 0.1 ha multi-scalevegetation plots. We recorded 330 plant species (1/3 thenumber of plants recorded in the 1074 km2 Park) in the2.2 ha area within the plots: this represents a samplingintensity of 0.29% of the 754 ha study site. We estimated 552plant species, about half the plant species recorded in the Park,in just 0.7% of the Parks area. We show how this rapid,cost-efficient methodology: (1) produces a rich informationbase on the patterns of native plant diversity and thedistribution of non-native plant species and keystoneecosystems; and (2) can be easily adapted for other nationaland state parks, national forests, wildlife refuges, and nature reserves. 相似文献
76.
Jonathan Ready Kristin Kaschner Paul D. Eastwood Josephine Rius Sven Kullander 《Ecological modelling》2010,221(3):467-478
We present and evaluate AquaMaps, a presence-only species distribution modelling system that allows the incorporation of expert knowledge about habitat usage and was designed for maximum output of standardized species range maps at the global scale. In the marine environment there is a significant challenge to the production of range maps due to large biases in the amount and location of occurrence data for most species. AquaMaps is compared with traditional presence-only species distribution modelling methods to determine the quality of outputs under equivalently automated conditions. The effect of the inclusion of expert knowledge to AquaMaps is also investigated. Model outputs were tested internally, through data partitioning, and externally against independent survey data to determine the ability of models to predict presence versus absence. Models were also tested externally by assessing correlation with independent survey estimates of relative species abundance. AquaMaps outputs compare well to the existing methods tested, and inclusion of expert knowledge results in a general improvement in model outputs. The transparency, speed and adaptability of the AquaMaps system, as well as the existing online framework which allows expert review to compensate for sampling biases and thus improve model predictions are proposed as additional benefits for public and research use alike. 相似文献
77.
78.
On 1 March 1997, powerful tornadoes touched down in Arkansas (USA) on a Saturday afternoon. Twenty-six fatalities and 400 non-fatal injuries were reported. We performed a population-based cross-sectional study to determine factors associated with appropriate responses to tornado warnings. Of 146 survey participants, 140 (96 per cent) knew the difference between 'tornado watch' and 'tornado warning' and were aware of when the warning was announced. Of those 140 participants, 64 (45.7 per cent) responded to the warning by seeking shelter, and 58 (90.6 per cent) of those 64 acted within five minutes of hearing the warning. Four factors were positively associated with those seeking shelter: having graduated from high school (OR = 4.2, 95 per cent CI = 1.1-15.5); having a basement in one's house (OR = 3.8, 95 per cent exact CI = 1.1-17.1); hearing a siren (OR = 4.4, 95 per cent CI = 1.3-18.9); and having prepared a household plan of response when tornadoes occur (OR = 2.6, 95 per cent CI = 1.1-6.3). On the basis of these findings, we recommend: first, that people who live in tornadoprone areas have a personal plan of action to help them respond immediately to warnings; second, public-health education officials in areas with frequent tornadic activity should do more to educate the public about what they can do to protect themselves from a tornado; and third, that emergency-management officials planning protection measures for vulnerable communities should consider that most people have limited time (our study documented five minutes) in which to respond to a tornado warning. Thus, shelters in tornado-prone areas should be quickly accessible by residents. 相似文献
79.
长春市西湖灌区土壤砷污染调查与评价 总被引:2,自引:0,他引:2
通过对长春市西湖灌区62个样点土壤砷含量的调查,评价该区域砷的污染状况。方法选择灌区稻田地、菜地、玉米地,以未利用土地为对照,采集耕层土壤样品,测定砷的含量,结果与吉林省土壤背景值比较,利用污染累积指数法评价砷的污染程度。结果未利用地砷含量(P〈0.05)与吉林省土壤背景值(8.38mg/kg)没有显著差剐;稻田、菜地、玉米地耕层土壤砷的算术平均值分别为12.79mg·kg^-1、11.96mg·kg^-1、11.19mg·kg^-1,明显高于吉林省土壤砷的背景值;三种土地利用方式下土壤砷的污染累积指数范围在1.90-1.17之间,并且土壤累积指数随着距污灌渠(口)距离的增大而减小。结论长期利用污水灌溉,导致砷在长春市西湖灌区耕层产生累积.土壤受到一定程度的污染。应当引起关注。 相似文献