全文获取类型
收费全文 | 68篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 4篇 |
环保管理 | 20篇 |
综合类 | 3篇 |
基础理论 | 28篇 |
污染及防治 | 6篇 |
评价与监测 | 6篇 |
灾害及防治 | 1篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 1篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有71条查询结果,搜索用时 31 毫秒
51.
We explored relationships of water quality parameters with landscape pattern metrics (LPMs), land use-land cover (LULC) proportions, and the advanced very high resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) or NDVI-derived metrics. Stream sites (271) in Nebraska, Kansas, and Missouri were sampled for water quality parameters, the index of biotic integrity, and a habitat index in either 1994 or 1995. Although a combination of LPMs (interspersion and juxtaposition index, patch density, and percent forest) within Ozark Highlands watersheds explained >60% of the variation in levels of nitrite-nitrate nitrogen and conductivity, in most cases the LPMs were not significantly correlated with the stream data. Several problems using landscape pattern metrics were noted: small watersheds having only one or two patches, collinearity with LULC data, and counterintuitive or inconsistent results that resulted from basic differences in land use-land cover patterns among ecoregions or from other factors determining water quality. The amount of variation explained in water quality parameters using multiple regression models that combined LULC and LPMs was generally lower than that from NDVI or vegetation phenology metrics derived from time-series NDVI data. A comparison of LPMs and NDVI indicated that NDVI had greater promise for monitoring landscapes for stream conditions within the study area. 相似文献
52.
Growth increments of the penaeid shrimp Penaeus vannamel (Boone) and P. schmitti (Burkenroad) grown in commercial production ponds in Ecuador and Colombia were measured over a 4 mo period between October 1987 and January 1988. P. vannamel grown from wild caught seed in Ecuadorian ponds exhibited a growth rhythm which significantly coincided with lunar phases. Growth increments of at least 1 gwk-1 occurred around a new and full moon, while growth increments of less than 1 gwk-1 occurred during first and last quarters. P. vannamel transported from Ecuador as nauplii, raised in Colombian hatcheries and on grown in Colombian ponds exhibited a cyclic pattern in wet weight increments but not correlation to lunar cycles was observed. P. schmitti showed no cyclic pattern in growth. The two species under consideration are indigenous to two different, and quite unique areas displaying different environmental characteristics. The link between the growth pattern, biological and lunar cycles is discussed. 相似文献
53.
van Belle Gerald Griffith William C. Edland Steven D. 《Environmental and Ecological Statistics》2001,8(2):171-180
The initial use of composite sampling involved the analysis of many negative samples with relatively high laboratory cost (Dorfman sampling). We propose a method of double compositing and compare its efficiency with Dorfman sampling. The variability of composite measurement samples has environmental interest (hot spots). The precision of these estimates depends on the kurtosis of the distribution; leptokurtic distributions (2 > 0) have increased precision as the number of field samples is increased. The opposite effect is obtained for platykurtic distributions. In the lognormal case, coverage probabilities are reasonable for < 0.5. The Poisson distribution can be associated with temporal compositing, of particular interest where radioactive measurements are taken. Sample size considerations indicate that the total sampling effort is directly proportional to the length of time sampled. If there is background radiation then increasing levels of this radiation require larger sample sizes to detect the same difference in radiation. 相似文献
54.
55.
Kumar S Dagar SS Mohanty AK Sirohi SK Puniya M Kuhad RC Sangu KP Griffith GW Puniya AK 《Die Naturwissenschaften》2011,98(6):457-472
Methanogens, the members of domain Archaea are potent contributors in global warming. Being confined to the strict anaerobic environment, their direct cultivation as
pure culture is quite difficult. Therefore, a range of culture-independent methods have been developed to investigate their
numbers, substrate uptake patterns, and identification in complex microbial communities. Unlike other approaches, fluorescence
in situ hybridization (FISH) is not only used for faster quantification and accurate identification but also to reveal the
physiological properties and spatiotemporal dynamics of methanogens in their natural environment. Aside from the methodological
aspects and application of FISH, this review also focuses on culture-dependent and -independent techniques employed in enumerating
methanogens along with associated problems. In addition, the combination of FISH with micro-autoradiography that could also
be an important tool in investigating the activities of methanogens is also discussed. 相似文献
56.
Geographic patterns of non-carpeted floor dust loading in Syracuse, New York (USA) homes 总被引:1,自引:0,他引:1
Johnson DL Hunt A Griffith DA Hager JM Brooks J Stellalevinsohn H Lanciki A Lucci R Prokhorova D Blount SL 《Environmental geochemistry and health》2009,31(3):353-363
Residential floor dust loading was measured on the smooth floor surface of 488 houses in Syracuse, New York, during the summers
of 2003 and 2004. Using U.S. Environmental Protection Agency (EPA) wipe methods, pre-weighed Ghost Wipes, Lead Wipes, or Whatman
Filters were employed to collect duplicate samples from (predominantly) kitchens. The collection efficiency of the various
media was determined from multiple wipe tests and side-by-side comparisons. The results were normalized and aggregated at
the census tract level to determine whether spatial patterns of dust loading could be observed. Loading was found to be log-normally
distributed, with a geometric mean value of 0.311 g m−2 (29 mg of dust per square foot of floor); 95% of the observations fell in the range of 0.042–2.330 g m−2 (4–216 mg foot−2). The sampling for floor dust loading shows some bias for day of the week in which visits to the residential properties were
made. After a first-order correction for this effect, results were aggregated by census tract and mapped in a geographic information
system (GIS); strong spatial patterns can be identified in an inverse distance weighted mapping. The geographic patterns exhibit
a strong correlation with socio-economic/demographic covariates extracted from the 2000 census summaries. Dust mass on the
floors is positively correlated with renter-occupied properties and family size; it is negatively correlated with measures
of household income. 相似文献
57.
Michael J. L. Magrath Peter Santema Karen M. Bouwman Dušan M. Brinkhuizen Simon C. Griffith Naomi E. Langmore 《Behavioral ecology and sociobiology》2009,63(5):661-672
Reproductive success within populations often varies with the timing of breeding, typically declining over the season. This
variation is usually attributed to seasonal changes in resource availability and/or differences in the quality or experience
of breeders. In colonial species, the timing of breeding may be of particular importance because the costs and benefits of
colonial breeding are likely to vary over the season and also with colony size. In this study, we examine the relationship
between timing of breeding and reproductive performance (clutch size and nest success) both within and between variable sized
colonies (n = 18) of fairy martins, Petrochelidon ariel. In four of these colonies, we also experimentally delayed laying in selected nests to disentangle the effects of laying
date and individual quality/experience on reproductive success. Within colonies, later laying birds produced smaller clutches,
but only in larger colonies. The general seasonal decline in nest success was also more pronounced in larger colonies. Late
laying birds were generally smaller than earlier laying birds, but morphological differences were also related to colony size,
suggesting optimal colony size also varies with phenotype. Experimentally delayed clutches were larger than concurrently produced
non-delayed clutches, but only in larger colonies. Similarly, delayed clutches were more likely to produce fledglings, particularly
later in the season and in larger colonies. We suggest that the reduced performance of late breeding pairs in larger colonies
resulted primarily from inexperienced/low quality birds preferring to settle in larger colonies, possibly exacerbated by an
increase in the costs of coloniality (e.g., resource depletion and ectoparasite infestations) with date and colony size. These
findings highlight the importance of phenotype-related differences in settlement decisions and reproductive performance to
an improved understanding of colonial breeding and variation in colony size. 相似文献
58.
Daniel M. Evans Stephen H. Schoenholtz Parker J. Wigington Jr Stephen M. Griffith William C. Floyd 《Environmental monitoring and assessment》2014,186(2):873-887
Research on relationships between dissolved nutrients and land-use at the watershed scale is a high priority for protecting surface water quality. We measured dissolved nitrogen (DN) and ortho-phosphorus (P) along 130 km of the Calapooia River (Oregon, USA) and 44 of its sub-basins for 3 years to test for associations with land-use. Nutrient concentrations were analyzed for spatial and seasonal patterns and for relationships with land-use and stream discharge. Ortho-P and DN were higher in lower-elevation sub-basins dominated by poorly drained soils and agricultural production compared with higher-elevation sub-basins dominated by well-drained soils and forests. Eight lower basins had at least one sample period with nitrate-N?>?10 mg L?1. The Calapooia River had lower concentrations of dissolved nutrients compared with lower sub-basins, often by an order of magnitude. Dissolved organic N represented a greater proportion of DN in the upper forested sub-basins. Seasonal nutrient concentrations had strong positive correlations to the percent of a sub-basin that was managed for agriculture in all seasons (p?values?≤?0.019) except summer. Results suggest that agricultural lands are contributing to stream nutrient concentrations. However, poorly drained soils in agricultural areas may also contribute to the strong relationships that we found between dissolved nutrients and agriculture. 相似文献
59.
60.
Fumiaki Y. Nomano Lucy E. Browning Shinichi Nakagawa Simon C. Griffith Andrew F. Russell 《Behavioral ecology and sociobiology》2014,68(8):1379-1391
The social network of preferences among group members can affect the distribution and consequences of collective behaviours. However, the behavioural contexts and taxa in which social network structure has been described are still limited because such studies require extensive data. Here, we highlight the use of an automated passive integrated transponder (PIT)-tag monitoring system for social network analyses and do so in a novel context—nestling provisioning in an avian cooperative breeder, for which direct observation of social behaviours is difficult. First, we used observers and cameras to arrive at a suitable metric of nest visit synchrony in the PIT-tag data. Second, we validated the use of this metric for social network analyses using internal nest video cameras. Third, we used hierarchical regression models with ‘sociality’ parameter to investigate structure of networks collected from multiple groups. Use of PIT tags led to nest visitation duration and frequency being obtained with a high degree of accuracy for all group members, except for the breeding female for whom accurate estimations required the use of a video camera due to her high variability in visitation time. The PIT-tag dataset uncovered significant variability in social network structure. Our results highlight the importance of combining complementary observation methods when conducting social network analyses of wild animals. Our methods can also be generalised to multiple contexts in social systems wherever repeated encounters with other individuals in closed space have ecological implications. 相似文献