全文获取类型
收费全文 | 17516篇 |
免费 | 298篇 |
国内免费 | 370篇 |
专业分类
安全科学 | 598篇 |
废物处理 | 738篇 |
环保管理 | 2597篇 |
综合类 | 3029篇 |
基础理论 | 4506篇 |
环境理论 | 7篇 |
污染及防治 | 4555篇 |
评价与监测 | 1000篇 |
社会与环境 | 1024篇 |
灾害及防治 | 130篇 |
出版年
2022年 | 158篇 |
2021年 | 167篇 |
2020年 | 196篇 |
2019年 | 144篇 |
2018年 | 290篇 |
2017年 | 265篇 |
2016年 | 402篇 |
2015年 | 323篇 |
2014年 | 453篇 |
2013年 | 1423篇 |
2012年 | 615篇 |
2011年 | 890篇 |
2010年 | 669篇 |
2009年 | 768篇 |
2008年 | 831篇 |
2007年 | 873篇 |
2006年 | 721篇 |
2005年 | 612篇 |
2004年 | 626篇 |
2003年 | 569篇 |
2002年 | 542篇 |
2001年 | 644篇 |
2000年 | 509篇 |
1999年 | 308篇 |
1998年 | 207篇 |
1997年 | 229篇 |
1996年 | 229篇 |
1995年 | 269篇 |
1994年 | 216篇 |
1993年 | 208篇 |
1992年 | 174篇 |
1991年 | 182篇 |
1990年 | 183篇 |
1989年 | 180篇 |
1988年 | 153篇 |
1987年 | 134篇 |
1986年 | 156篇 |
1985年 | 144篇 |
1984年 | 190篇 |
1983年 | 147篇 |
1982年 | 171篇 |
1981年 | 157篇 |
1980年 | 130篇 |
1979年 | 149篇 |
1978年 | 94篇 |
1977年 | 98篇 |
1975年 | 88篇 |
1974年 | 93篇 |
1973年 | 86篇 |
1972年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Keri L. Christensen Anthony P. Gallacher Lizzie Martin Desmond Tong Mark A. Elgar 《Die Naturwissenschaften》2010,97(10):941-944
The geometric framework model predicts that animal foraging decisions are influenced by their dietary history, with animals targeting a combination of essential nutrients through compensatory foraging. We provide experimental confirmation of nutrient-specific compensatory foraging in a natural, free-living population of social insects by supplementing their diet with sources of protein- or carbohydrate-rich food. Colonies of the ant Iridomyrmex suchieri were provided with feeders containing food rich in either carbohydrate or protein for 6 days, and were then provided with a feeder containing the same or different diet. The patterns of recruitment were consistent with the geometric framework: while feeders with a carbohydrate diet typically attracted more workers than did feeders with protein diet, the difference in recruitment between the two nutrients was smaller if the colonies had had prior access to carbohydrate than protein. Further, fewer ants visited feeders if the colony had had prior access to protein than to carbohydrates, suggesting that the larvae play a role in worker foraging behaviour. 相似文献
82.
H.P. Jarvie P.J.A. Withers M.J. Bowes E.J. Palmer-Felgate D.M. Harper K. Wasiak P. Wasiak R.A. Hodgkinson A. Bates C. Stoate M. Neal H.D. Wickham S.A. Harman L.K. Armstrong 《Agriculture, ecosystems & environment》2010,135(4):238-252
This paper provides an overview of the impacts of rural land use on lowland streamwater phosphorus (P) and nitrogen (N) concentrations and P loads and sources in lowland streams. Based on weekly water quality monitoring, the impacts of agriculture on streamwater P and N hydrochemistry were examined along a gradient of rural–agricultural land use, by monitoring three sets of ‘paired’ (near-adjacent) rural headwater streams, draining catchments which are representative of the major geology, soil types and rural/agricultural land use types of large areas of lowland Britain. The magnitude and timing of P and N inputs were assessed and the load apportionment model (LAM) was applied to quantify ‘continuous’ (point) source and ‘flow-dependent’ (diffuse) source contributions of P to these headwater streams. The results show that intensive arable farming had only a comparatively small impact on streamwater total phosphorus (TP loads), with highly consistent stream diffuse-source TP yields of ca. 0.5 kg-P ha?1 year?1 for the predominantly arable catchments with both clay and loam soils, compared with 0.4 kg-P ha?1 year?1 for low agricultural intensity grassland/woodland on similar soil types. In contrast, intensive livestock farming on heavy clay soils resulted in dramatically higher stream diffuse-source TP yields of 2 kg-P ha?1 year?1. The streamwater hydrochemistry of the livestock-dominated catchment was characterised by high concentrations of organic P, C and N fractions, associated with manure and slurry sources. Across the study sites, the impacts of human settlement were clearly identifiable with effluent inputs from septic tanks and sewage treatment works resulting in large-scale increases in soluble reactive phosphorus (SRP) loads and concentrations. At sites heavily impacted by rural settlements, SRP concentrations under baseflow conditions reached several hundred μg-P L?1. Load apportionment modelling demonstrated significant ‘point-source’ P inputs to the streams even where there were no sewage treatment works within the upstream catchment. This indicates that, even in sparsely populated rural headwater catchments, small settlements and even isolated groups of houses are sufficient to cause significant nutrient pollution and that septic tank systems serving these rural communities are actually operating as multiple point sources, rather than a diffuse input. 相似文献
83.
84.
85.
Behavioral responses to information about forecasted air quality may introduce systematic measurement error in pollution exposure, leading to biased estimates of the impact of pollution exposure on health. This paper estimates the statistical association between ambient ozone concentrations and asthma hospitalizations in Southern California while accounting for potential avoidance behavior in response to forecasted air quality. Data on asthma hospital admissions were merged with observed and forecasted air quality and meteorological data at the daily level for the years 1989–1997. A distributed lag Poisson generalized linear model allowing for overdispersion was estimated. Accounting for potential responses to information about pollution leads to significantly larger estimates of the relationship between ozone concentrations and asthma hospital admissions, particularly for susceptible populations. Individuals take substantial actions to reduce exposure to ozone; estimates of the concentration–response function for ozone that ignore these actions are biased towards the null and may significantly understate the costs to society from ozone concentrations. 相似文献
86.
Hepatitis A virus (HAV) is currently recognized as an important human food borne pathogen, and it is one of the most resistant
enteric RNA viruses, is highly infectious, and may lead to widespread outbreaks. The aim of this study was to optimize the
methods to detect HAV from artificially contaminated food. To this end, strawberry and lettuce were experimentally contaminated
with HAV suspension containing 6 × 106 copies/ml. After contamination, HAV persistence and washing procedure were evaluated at 0, 1, 3, 7, and 9 days of storage.
Five elution buffers (PBS (pH 7.4)/0.1% Tween80; 50 mM glycine/3% (wt/vol) beef extract (pH 9.5); PBS (pH 7, 4); 25 mM glycine/0.1
Tween80; and 1 M sodium bicarbonate) were used to elute the virus, and qualitative and quantitative PCR were used for HAV
detection. HAV was detected by qualitative and quantitative PCR using any of the five elution buffers, but PBS was the most
effective. Even after washing, HAV was detected up to 9 days after contamination by quantitative PCR. Quantitative PCR was
more sensitive than qualitative PCR since samples containing viral load lower than 1.4 × 103 copies/ml could not be detected by qualitative PCR. Quantitative PCR can be used for rapid detection of food borne viruses
and will help in the monitoring and control of food borne disease. 相似文献
87.
Ingeborg L. A. Boxman 《Food and environmental virology》2010,2(3):156-166
Different sources were consulted to obtain information on the occurrence of viruses in bivalve molluscs on the European market.
Twenty-six peer-reviewed articles were identified reporting on the molecular detection of viral RNA in 4,260 samples in total.
The data obtained will be presented geographically on virus types detected, the origin and treatment of the shellfish, and
the detection technique applied. The data demonstrate that viral RNA can be detected in shellfish from polluted areas, in
depurated shellfish as well as those for human consumption. The European Rapid Alert System for Food and Feed (RASFF) database
was consulted as another source. Twenty-eight notifications were identified on the presence of hepatitis A virus or norovirus
in shellfish on the European market. The most recent report of the European laboratory network was referred to, to gain insight
into the laboratory capability at present for the analyses of shellfish on the presence of viruses. Approximately 67% of 27
participating laboratories obtained intended results for all samples, consisting of lenticules loaded with 103 copies norovirus (genogroup I (GGI) and/or genogroup II (GGII)) and/or 1 × 105–8 × 104 copies of hepatitis A virus. From 1993, there has been a continuous development of molecular detection techniques and tools
have been described to ensure quality assurance. End product testing will, however, not be achievable. As depuration has been
shown not to be effective for the complete elimination of viruses, shellfish should not be in contact with faecal contaminated
water in order to minimise the risk of shellfish-transmittable viral diseases. 相似文献
88.
上海中心城区苏州河沿岸排水系统降雨径流水文水质特性研究 总被引:4,自引:0,他引:4
为了解城市合流制管道系统降雨径流的水文水质变化过程与特征,于2007年7~9月对上海中心城区合流制排水系统(CSS)4类强度降雨(小雨、中雨、大雨和暴雨)的降雨量、径流量和污染浓度进行了同步连续监测与分析.结果表明,径流过程线滞后于降雨过程线约15~25 min,形态与降雨过程线相似,波动幅度低于降雨过程线.4类强度降雨的径流系数分别为:0.33、 0.62、 0.67和0.73.CSS基本存在30/30标准的降雨径流初始冲刷现象,污染物浓度过程线滞后于降雨过程线约30~40 min. 4类强度降雨径流的pH值和重金属Cu、Zn、Cr、Cd、Pb、Ni的事件平均浓度(EMC)均符合地表水环境质量标准Ⅴ类水要求,COD、BOD5、NH+4-N和TP的EMC的变化范围分别为225.0~544.1、 31.5~98.9、 8.9~44.2和1.98~3.52 mg·L-1,平均分别超过Ⅴ类水标准9.3、 5.6、 11.7和6.1倍,接近国外城市CSS的平均污染水平.SS与COD、BOD5、NH+4-N和TP在P<0.01水平上均具有一定的正相关性(R为0.359~0.736),颗粒态有机类和营养类污染物的比例平均为70.21%. 相似文献
89.
L. Claessens J.M. Schoorl P.H. Verburg L. Geraedts A. Veldkamp 《Agriculture, ecosystems & environment》2009,129(1-3):157-170
Land use changes and landscape processes are interrelated and influenced by multiple bio-physical and socio-economic driving factors, resulting in a complex, multi-scale system. Consequently in landscapes with active landscape processes such as erosion, land use changes should not be analysed in isolation without accounting for both on-site and off-site effects on landscape processes. To investigate the interactions between land use, land use change and landscape processes, a case study for the Álora region in southern Spain is carried out, coupling a land use change model (CLUE) and a landscape process model simulating water and tillage erosion and sedimentation (LAPSUS). First, both models are run independently for a baseline scenario of land use change. Secondly, different feedbacks are added to the coupled model framework as ‘interaction scenarios’. Firstly effects of land use change on landscape processes are introduced by means of a ‘changed erodibility feedback’. Secondly effects of landscape processes on land use are introduced stepwise: (i) an ‘observed erosion feedback’ where reallocation of land use results from farmers’ perception of erosion features, and (ii) a ‘reduced productivity feedback’ whereby changes in soil depth result in a land use relocation. Quantities and spatial patterns of both land use change and soil redistribution are compared with the baseline scenario to assess the cumulative effect of including each of the interaction mechanisms in the modelling framework.Overall, total quantities of land use change (areas) and soil redistribution do not differ much for the different interaction scenarios. However, there are important differences in the spatial patterns of both land use and soil redistribution. In addition, by incorporating the perception and bio-physical feedback mechanisms, land use types with stable or increasing acreages are increasingly relocated from their original positions, suggesting a current location on landscape positions prone to soil erosion and sedimentation. Implementing the ‘reduced productivity feedback’ causes most of these effects. Another important outcome is that on-site land use changes trigger major off-site soil redistribution dynamics. These off-site effects are attributed to down slope or downstream changes in sediment transport rates and/or discharge caused by changes in land surface characteristics.The results of this study provide insight into the interactions between different processes occurring within landscapes and the influence of feedbacks on the development of the landscape. The interaction between processes goes across various spatial and temporal scales, leading to difficulties in linked model representation and calibration and validation of the coupled modelling system. 相似文献
90.
Both phytophagous and parasitic insects deposit oviposition-marking pheromones (OMPs) following oviposition that function
to inform conspecifics of a previously utilized host of reduced suitability. The blueberry maggot fly, Rhagoletis mendax Curran (Diptera: Tephritidae), deposits eggs individually into blueberries and then marks the fruit surface with an OMP which
reduces acceptance of fruit for oviposition by conspecifics. Diachasma alloeum (Muesebeck) (Hymenoptera: Braconidae) is a parasitic wasp attacking larval R. mendax which also deposits an OMP, signaling conspecifics of a wasp-occupied host. Behavioral studies were conducted testing the
hypothesis that the OMP of the parasitic wasp modifies the oviposition behavior of its host fly. In this study, we show that
the OMP of D. alloeum is recognized by R. mendax, and female flies will reject wasp-marked fruit for oviposition. Thus, we present a rare demonstration of pheromonal recognition
between animals occupying different taxonomic orders and trophic levels. This chemical eavesdropping may enhance the ability
of the fly to avoid fruit unsuitable for larval development. 相似文献