全文获取类型
收费全文 | 3312篇 |
免费 | 68篇 |
国内免费 | 33篇 |
专业分类
安全科学 | 120篇 |
废物处理 | 102篇 |
环保管理 | 609篇 |
综合类 | 521篇 |
基础理论 | 868篇 |
环境理论 | 9篇 |
污染及防治 | 797篇 |
评价与监测 | 192篇 |
社会与环境 | 148篇 |
灾害及防治 | 47篇 |
出版年
2023年 | 15篇 |
2022年 | 17篇 |
2021年 | 39篇 |
2020年 | 20篇 |
2019年 | 32篇 |
2018年 | 79篇 |
2017年 | 76篇 |
2016年 | 83篇 |
2015年 | 86篇 |
2014年 | 95篇 |
2013年 | 243篇 |
2012年 | 156篇 |
2011年 | 202篇 |
2010年 | 149篇 |
2009年 | 163篇 |
2008年 | 174篇 |
2007年 | 205篇 |
2006年 | 205篇 |
2005年 | 150篇 |
2004年 | 107篇 |
2003年 | 102篇 |
2002年 | 116篇 |
2001年 | 65篇 |
2000年 | 59篇 |
1999年 | 49篇 |
1998年 | 50篇 |
1997年 | 60篇 |
1996年 | 46篇 |
1995年 | 54篇 |
1994年 | 49篇 |
1993年 | 29篇 |
1992年 | 31篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1965年 | 11篇 |
1963年 | 8篇 |
1957年 | 10篇 |
排序方式: 共有3413条查询结果,搜索用时 15 毫秒
121.
Peter Bacopoulos Ethan J. Kubatko Scott C. Hagen Andrew T. Cox Teddy Mulamba 《Environmental Fluid Mechanics》2017,17(2):323-353
Continuous data of vertical-profile salinity were analyzed for four stations located successively upriver in a macrotidal estuary, the lower St. Johns River (Northeast Florida, USA). The data analysis confirmed well-mixed salinity conditions in the river with at most 1.3 ppt of vertical variability at Dames Point (river km 20), where the main variations of salinity are along the longitudinal axis of the river. Given the well-mixed salinity conditions and dominant horizontal structure of salinity variations in the river, we present and apply a barotropic, two-dimensional modeling approach for hydrodynamic-salinity transport simulation in the lower St. Johns River. When properly forced by offshore surge, high-resolution wind fields and freshwater river inflows, the model replicated the salinity measurements remarkably well, including the separation into tidal and sub-tidal components. The data and model results show that, at times, offshore winds and surge can be more influential on longitudinal salinity variations than local winds over the river. We demonstrate the importance of using proper boundary conditions to force the model relative to the minimal sensitivity of the model to parameter adjustment of horizontal mixing and uncertainty-based perturbation of wind and inflow forcings. 相似文献
122.
Matt Dodd G. Mark Richardson Ross Wilson Andy Rencz Peter Friske 《Environmental geochemistry and health》2017,39(4):759-777
Elemental concentrations and bioaccessibility were determined in background soils collected in Canada as part of the North American Geochemical Landscapes Project. The concentrations of As, Cr, Cu, Co, Ni and Zn were higher in the C-horizon (parent material) compared to 0–5 cm (surface soil), and this observation along with the regional distribution suggested that most of the variability in concentrations of these elements were governed by the bedrock characteristics. Unlike the above-stated elements, Pb and Cd concentrations were higher in the surface layer reflecting the potential effects of anthropogenic deposition. Elemental bioaccessibility was variable decreasing in the order Cd > Pb > Cu > Zn > Ni > Co > As > Cr for the surface soils. With the exception of As, bioaccessibility was generally higher in the C-horizon soils compared to the 0–5 cm soils. The differences in metal bioaccessibility between the 0–5 cm and the C-horizon and among the provinces may reflect geological processes and speciation. The mean, median or 95th percentile bioaccessibility for As, Cr, Cu, Co, Ni and Pb were all below 100 %, suggesting that the use of site-specific bioaccessibility results for these elements will yield more accurate estimation of the risk associated with oral bioavailability for sites where soil ingestion is the major contributor of human health risk. 相似文献
123.
Land systems are described based on various characteristics, including land cover composition and agricultural production. However, it is uncertain to what extent livestock, particularly monogastric livestock, determines land systems. We included monogastrics in a land system classification, and statistically analyzed the land cover composition and agricultural production of otherwise similar land systems with and without monogastric livestock. The results indicate that land systems with monogastrics are statistically different from their counterparts in the classification without monogastrics in terms of grassland area and crop yields, but are less different in terms of tree area, crop area, and ruminant livestock production. We then used a land systems map that includes monogastrics in the classification and a similar map that does not include monogastrics to project future changes in a novel manner that integrates livestock as a determinant of land systems. The results show that including monogastrics in otherwise similar projections yields less cropland intensification and more cropland expansion in several world regions, including Northern Africa and the Middle East. Other regions, such as Europe and Australia, were characterized by less decrease or more increase in tree area in the application with monogastrics, mainly due to the occurrence of open forests with monogastrics. This study prompts a call for improved characterization of land systems for land use and cover change (LUCC) assessments in order to better represent LUCC driven by monogastric livestock. 相似文献
124.
125.
This paper introduces a model, which is enabling a comparison between universities regarding research, educational and environmental performances; the mission of university fits the sustainability idea. The purpose of the paper is to improve the methodology and indicators of the existing ranking tables. The three dimensional index, which provides simplified information about the quality of universities, has been developed. It enables quick detection of the weaknesses, strengths and opportunities for universities. Weights of indicators were determined using the analytic hierarchy process (AHP). Results of the AHP have shown that the most important are research oriented indicators, followed by social and environmental ones.The proposed model has been tested on a sample of 35 top universities from the ARWU (Academic Ranking of World Universities) and Times ranking tables and a new ranking table – the Three dimensional University Ranking (TUR) has been developed. In addition, correlations between indicators and ranking tables have been carried out. There is only a medium correlation between the ARWU and TUR. Regarding the indicators, a high correlation with Hirsch indices and Highly Cited Researchers exists, while there is an insignificant correlation between the low student to staff ratio and the graduation rate. 相似文献
126.
Coeloides bostrichorum Giraud parasitoids (Hymenoptera: Braconidae) attack late larval stages of various bark beetle species breeding in spruce. Volatile compounds collected from Norway spruce (Picea abies) infested by Ips typographus L. (Coleoptera: Scolytidae) were analysed by coupled gas chromatography-mass spectrometry (GC-MS) and GC-electroantennographic detection (GC-EAD). Monoterpene hydrocarbons are the predominant volatile compounds of fresh Norway spruce, while the presence of oxygenated monoterpenes indicates damaged trees. Between one and eight EAD-active oxygenated monoterpenes were used, in amounts reflecting their natural abundance in spruce trees containing bark beetle larvae, to prepare five synthetic baits which were tested in wind tunnel bioassays. Odour samples collected from spruce logs containing the preferred host stage were attractive, while similar samples from uninfested logs failed to elicit any flight activity. However, when a four- or an eight-component synthetic bait was added to volatiles collected from uninfested spruce logs, this combination was as attractive as volatiles collected from infested spruce logs. 相似文献
127.
Alan R. Thornhill John A. McGrath Robin A. J. Eady Peter R. Braude Alan H. Handyside 《黑龙江环境通报》2001,21(6):490-497
Single cell polymerase chain reaction (PCR) for preimplantation genetic diagnosis (PGD) requires high efficiency and accuracy. Allele dropout (ADO), the random amplification failure of one of the two parental alleles, remains the most significant problem in PCR-based PGD testing since it can result in serious misdiagnosis for compound heterozygous or autosomal dominant conditions. A number of different strategies (including the use of lysis buffers to break down the cell and make the DNA accessible) have been employed to combat ADO with varying degrees of success, yet there is still no consensus among PGD centres over which lysis buffer should be used (ESHRE PGD Consortium, 1999 ). To address this issue, PCR amplification of three genes (CFTR, LAMA3 and PKP1) at different chromosomal loci was investigated. Single lymphocytes from individuals heterozygous for mutations within each of the three genes were collected and lysed in either alkaline lysis buffer (ALB) or proteinase K/SDS lysis buffer (PK). PCR amplification efficiencies were comparable between alkaline lysis and proteinase K lysis for PCR products spanning each of the three mutated loci (ΔF508 in CFTR 90% vs 88%; R650X in LAMA3 82% vs 78%; and Y71X in PKP1 91% vs 87%). While there was no appreciable difference between ADO rates between the two lysis buffers for the LAMA3 PCR product (25% vs 26%), there were significant differences in ADO rates between ALB and PK for the CFTR PCR product (0% vs 23%) and the PKP1 PCR product (8% vs 56%). Based on these results, we are currently using ALB in preference to PK/SDS buffer for the lysis of cells in clinical PGD. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
128.
Ronald J. Wapner Thomas M. Jenkins Neil Silverman Marion Kaufmann Cheryl Hannau Peter McCue 《黑龙江环境通报》2001,21(4):256-261
The diagnosis of congenital nephrosis is difficult during the antepartum period. The combination of an elevated amniotic fluid alpha-fetoprotein, a negative acetylcholinesterase, and a negative ultrasound examination is highly indicative of congenital nephrosis; however, these findings can also be associated with a normal gestation. This is the first report of pathologic confirmation of congenital nephrosis from an in utero fetal kidney biopsy. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
129.
Liangyun Liu Huan Tang Peter Caccetta Eric A. Lehmann Yong Hu Xiaoliang Wu 《Environmental monitoring and assessment》2013,185(12):9949-9965
The Three-North Shelter Forest Program is the largest afforestation reconstruction project in the world. Remote sensing is a crucial tool to map land use and land cover change, but it is still challenging to accurately quantify the change in forest extent from time-series satellite images. In this paper, 30 Landsat MSS/TM/ETM+ epochs from 1974 to 2012 were collected, and the high-quality ground surface reflectance (GSR) time-series images were processed by integrating the 6S atmosphere transfer model and a relative reflectance normalization algorithm. Subsequently, we developed a vegetation change tracking method to reconstruct the forest change history (afforestation and deforestation) from the time-series Landsat GSR images based on the integrated forest z-score (IFZ) model by Huang et al. (2009a), which was improved by multi-phenological IFZ models and the smoothing processing of IFZ data for afforestation mapping. The mapping result showed a large increase in the extent of forest, from 380,394 ha (14.8 % of total district area) in 1974 to 1,128,380 ha (43.9 %) in 2010. Finally, the land cover and forest change map was validated with an overall accuracy of 89.1 % and a kappa coefficient of 0.858. The forest change time was also successfully retrieved, with 22.2 % and 86.5 % of the change pixels attributed to the correct epoch and within three epochs, respectively. The results confirmed a great achievement of the ecological revegetation projects in Yulin district over the last 40 years and also illustrated the potential of the time-series of Landsat images for detecting forest changes and estimating tree age for the artificial forest in a semi-arid zone strongly influenced by human activities. 相似文献
130.
Christopher Buzzelli Melanie Parker Stephen Geiger Yongshan Wan Peter Doering Daniel Haunert 《Environmental Modeling and Assessment》2013,18(2):185-198
Oyster populations in south Florida estuaries have declined in part through altered salinity driven by anthropogenic changes in freshwater inputs. In particular, the St. Lucie Estuary (SLE) in southeastern Florida has suffered widespread loss of oyster habitat. With efforts underway to improve water quality and oyster habitat in the SLE, the goal of this study was to develop a model to assess ecosystem level impacts of oyster restoration. Phytoplankton and oyster biomass modeling targets were established from observational data collected from 2005 to 2009. Modeled oyster biomass production and filtration fluctuated with temperature, salinity, and total suspended solids from a combination of observational and predicted input functions in 10-year simulations (1998–2007). Model estimates of oyster biomass fluctuated with salinity from near zero after extreme freshwater discharge in 2002–2003 and 2004–2005 to maximum values near 150.0 and 200.0 g?C?m?2 in spring 1999 and fall 2006. There was potential for algal blooms as turnover time for the phytoplankton standing stock (15.6 days) was faster than water mass turnover (21.0 days). While >1,000 days were required for 50 ha of oyster habitat to filter the entire volume of the estuarine segment, filter time reduced to <20 days with an estimated fivefold increase in net consumption of phytoplankton if the oyster habitat was increased to 300 ha. Re-establishment of biologically desirable salinity envelopes would stabilize oyster survival allowing the possibility for successful habitat restoration to benefit water quality and faunal attributes of the St. Lucie Estuary. 相似文献