全文获取类型
收费全文 | 363篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 16篇 |
废物处理 | 6篇 |
环保管理 | 96篇 |
综合类 | 51篇 |
基础理论 | 100篇 |
环境理论 | 2篇 |
污染及防治 | 64篇 |
评价与监测 | 23篇 |
社会与环境 | 13篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 11篇 |
2013年 | 32篇 |
2012年 | 18篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 19篇 |
2008年 | 18篇 |
2007年 | 18篇 |
2006年 | 20篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 23篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有373条查询结果,搜索用时 15 毫秒
61.
62.
Three types of soil-gas surveys were performed over the same location at an industrial facility. The surveys performed were (1) a passive technique using buried collectors, (2) an active technique in which samples were collected in the field by pumping with subsequent analysis at a field laboratory, and (3) a screening technique that employed a hand-held survey instrument. Each of the surveys had desirable features, but there was considerable variability in the quality of data obtained, cost, and ease of performance. The passive and active surveys provided excellent detection limits, but the passive technique does not provide data in real time. The active survey was also time-consuming and required an analytical chemist in the field. Neither the active nor the passive survey were able to delineate the plume of contaminated groundwater. Consequently, the results from the rapid and inexpensive reconnaissance technique provided functionally equivalent data.Publication No. 3672, Environmental Sciences Division, ORNL.Operated by Martin Marietta Energy Systems, Inc. for the U.S. Department of Energy under Contract No. DE-AC05-840R21400. 相似文献
63.
64.
Agnes M. L. Karlson Jon Duberg Nisha H. Motwani Hedvig Hogfors Isabell Klawonn Helle Ploug Jennie Barthel Svedén Andrius Garbaras Brita Sundelin Susanna Hajdu Ulf Larsson Ragnar Elmgren Elena Gorokhova 《Ambio》2015,44(3):413-426
Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N2 allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea. 相似文献
65.
Length of maternal care, i.e. the interval between successfully raised litters, is the most important factor explaining the variation in reproductive rate among brown-bear (Ursus arctos) populations. In this paper, we examine the variation in length of maternal care in radio-marked brown bears and its effect on their offspring in northern Sweden. Young stayed with their mothers for 1.4–1.5 or 2.4–2.5 (in one case 3.5) years and were weaned with body masses varying from 17 to 69 kg. The probability of yearling litters staying with their mother for a 2nd year increased with decreasing yearling body mass, and was higher for litters with two offspring than for litters with one or three to four offspring. Staying with their mothers for a 2nd year had a positive effect on mass gain in yearlings and this effect was more pronounced in litters with two than three to four offspring. Body mass of 2-year-olds was not related to age of weaning, suggesting that keeping offspring for an additional year mainly compensated for low yearling body mass. If large offspring body mass positively affects later offspring survival and reproduction, mothers may be able to optimize the length of maternal care according to the litter size and the size of their yearlings.Communicated by F. Trillmich 相似文献
66.
67.
Jon P. Nelson 《Journal of Environmental Economics and Management》1979,6(4):320-331
The present study reports on the influence of aircraft noise on housing prices in the vicinity of six major U.S. airports, including San Francisco, St. Louis, Cleveland, New Orleans, San Diego, and Buffalo. The sampling procedures attempt to control for the effect of accessibility on location rent, and hence, housing prices. Regression results are reported for the individual samples and for a pooled sample consisting of 845 observations. The regression coefficients for aircraft noise are stable about their weighted mean and are comparable to coefficient estimates from the pooled sample. Dummy variables and partitioned regressions are used to test for remaining accessibility effects. 相似文献
68.
Statistical inference on patch-specific survival and movement rates from marked animals 总被引:1,自引:0,他引:1
Michael J. Conroy Jon E. Anderson Stephen L. Rathbun David G. Krementz 《Environmental and Ecological Statistics》1996,3(2):99-116
Empirical estimates of patch-specific survival and movement rates are needed to parametrize spatially explicit population
models, and for inference on the effects of habitat quality and fragmentation on populations. Data from radio-marked animals,
in which both the fates and habitat locations of animals are known over time, can be used in conjunction with continuous-time
proportional hazards models to obtain inferences on survival rates. Discrete-time conditional logistic models may provide
inference on both survival and movement rates. We use Monte Carlo simulation to investigate accuracy of estimates of survival
from both approaches, and movement rates from conditional logistic regression, for two habitats. Bias was low (relative bias
< 0.04) and interval coverage accurate (close to the nominal 0.95) for estimates of habitat effect on survival based on proportional
hazards. Bias was high (
relative bias 0.60) and interval coverage poor (
= 0.26 vs. nominal 0.95) for estimates of habitat effect based on conditional logistic regression; bias was especially influenced
by heterogeneity in survival and the shape of the hazard function, whereas both bias and coverage were affected by ‘memory’
effects in movement patterns. Bias estimates of movement rate was low (
relative bias < 0.05), but interval coverage was poor (
= 0.48–0.80), possibly as a result of poor performance of a Taylor series estimate of variance. An example is provided from
a radio-telemetry study of 47 wintering American woodcock (Scolopax minor), illustrating practical difficulties in field studies to parametrize these models. We also discuss extensions of continuous-time
models to explicitly include a movement process, and further examine tradeoffs between continuous and discrete models. 相似文献
69.
Elie Gaget Diego Pavón-Jordán Alison Johnston Aleksi Lehikoinen Wesley M. Hochachka Brett K. Sandercock Alaaeldin Soultan Hichem Azafzaf Nadjiba Bendjedda Taulant Bino Luka Božič Preben Clausen Mohamed Dakki Koen Devos Cristi Domsa Vitor Encarnação Kiraz Erciyas-Yavuz Sándor Faragó Teresa Frost Clemence Gaudard Lívia Gosztonyi Fredrik Haas Menno Hornman Tom Langendoen Christina Ieronymidou Vasiliy A. Kostyushin Lesley J. Lewis Svein-Håkon Lorentsen Leho Luigujõe Włodzimierz Meissner Tibor Mikuska Blas Molina Zuzana Musilová Viktor Natykanets Jean-Yves Paquet Nicky Petkov Danae Portolou Jozef Ridzoň Samir Sayoud Marko Šćiban Laimonas Sniauksta Antra Stīpniece Nicolas Strebel Norbert Teufelbauer Goran Topić Danka Uzunova Andrej Vizi Johannes Wahl Marco Zenatello Jon E. Brommer 《Conservation biology》2021,35(3):834-845
Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming. 相似文献
70.
Influence of sediment on the fate and toxicity of a polyethoxylated tallowamine surfactant system (MON 0818) in aquatic microcosms 总被引:1,自引:0,他引:1
Wang N Besser JM Buckler DR Honegger JL Ingersoll CG Johnson BT Kurtzweil ML Macgregor J McKee MJ 《Chemosphere》2005,59(4):545-551
The fate and toxicity of a polyethoxylated tallowamine (POEA) surfactant system, MON 0818, was evaluated in water-sediment microcosms during a 4-d laboratory study. A surfactant solution of 8 mg l(-1) nominal concentration was added to each of nine 72-l aquaria with or without a 3-cm layer of one of two natural sediments (total organic carbon (TOC) 1.5% or 3.0%). Control well water was added to each of nine additional 72-l aquaria with or without sediment. Water samples were collected from the microcosms after 2, 6, 24, 48, 72, and 96 h of aging to conduct 48-h toxicity tests with Daphnia magna and to determine surfactant concentrations. Elevated mortality of D. magna (43-83%) was observed in overlying water sampled from water-only microcosms throughout the 96-h aging period, whereas elevated mortality (23-97%) was only observed in overlying water sampled from water-sediment microcosms during the first 24h of aging. Measured concentrations of MON 0818 in water-only microcosms remained relatively constant (4-6 mg l(-1)) during the 96-h period, whereas the concentrations in overlying water from microcosms containing either of the two types of sediment dissipated rapidly, with half-lives of 13 h in the 3.0% TOC sediment and 18 h in the 1.5% TOC sediment. Both toxicity and the concentration of MON 0818 in overlying water decreased more rapidly in microcosms containing sediment with the higher percent TOC and clay and with a higher microbial biomass. Mortality of D. magna was significantly correlated with surfactant concentrations in the overlying water. These results indicate that the toxicity of the POEA surfactant in water rapidly declines in the presence of sediment due to a reduction in the surfactant concentration in the overlying water above the sediment. 相似文献