全文获取类型
收费全文 | 17293篇 |
免费 | 143篇 |
国内免费 | 112篇 |
专业分类
安全科学 | 406篇 |
废物处理 | 654篇 |
环保管理 | 1922篇 |
综合类 | 5325篇 |
基础理论 | 3578篇 |
环境理论 | 2篇 |
污染及防治 | 4104篇 |
评价与监测 | 879篇 |
社会与环境 | 617篇 |
灾害及防治 | 61篇 |
出版年
2018年 | 200篇 |
2017年 | 189篇 |
2016年 | 285篇 |
2015年 | 216篇 |
2014年 | 318篇 |
2013年 | 1158篇 |
2012年 | 369篇 |
2011年 | 520篇 |
2010年 | 497篇 |
2009年 | 554篇 |
2008年 | 573篇 |
2007年 | 597篇 |
2006年 | 527篇 |
2005年 | 465篇 |
2004年 | 506篇 |
2003年 | 460篇 |
2002年 | 437篇 |
2001年 | 618篇 |
2000年 | 412篇 |
1999年 | 283篇 |
1998年 | 207篇 |
1997年 | 195篇 |
1996年 | 194篇 |
1995年 | 230篇 |
1994年 | 242篇 |
1993年 | 207篇 |
1992年 | 225篇 |
1991年 | 234篇 |
1990年 | 253篇 |
1989年 | 230篇 |
1988年 | 181篇 |
1987年 | 181篇 |
1986年 | 180篇 |
1985年 | 180篇 |
1984年 | 200篇 |
1983年 | 187篇 |
1982年 | 196篇 |
1981年 | 208篇 |
1980年 | 169篇 |
1979年 | 181篇 |
1978年 | 147篇 |
1977年 | 139篇 |
1974年 | 147篇 |
1973年 | 147篇 |
1968年 | 156篇 |
1967年 | 184篇 |
1966年 | 154篇 |
1965年 | 148篇 |
1964年 | 151篇 |
1963年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
921.
Existing methods for the comparison of genotoxic effects in the comet assay bear considerable disadvantages such as the problem to link information about concentration dependence and severity of effects. Moreover, given the lack of standardized protocols and the use of various standards, it may be extremely difficult to compare different studies. In order to provide a method for standardized comparative assessment of genotoxic effects, the concept of genotoxicity equivalents (Gene-TEQ) was developed. As potential reference compounds for genotoxic effects, three directly acting (N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methyl-methanesulfonate, and N-methyl-N-nitrosourea) and three indirectly acting (cyclophosphamide, dimethylnitrosamine, and 4-nitroquinoline-oxide) genotoxic substances were compared with respect to their cytotoxic (neutral red) and genotoxic (comet assay) concentration-response profiles in the permanent fish cell line RTL-W1. For further comparison, two sediment extracts from the upper Danube River were investigated as environmental samples. Based on the results of cytotoxicity and genotoxicity testing, MNNG was selected as the reference compound. At several exposure levels and durations, genotoxic effects of both the other pure substances and the environmental samples were calculated as percentages of the maximum MNNG effect and related to the absolute MNNG effect (EC values). Thus, genotoxicity equivalent factors (Gene-TEQs) relative to MNNG could be calculated. Gene-TEQs can easily be applied to pure substances, mixtures and field samples to provide information about their toxicity relative to the reference compound. Furthermore, the Gene-TEQ concept allows a direct comparison of environmental samples from different laboratories. 相似文献
922.
Understanding the spatial soil salinity aids farmers and researchers in identifying areas in the field where special management practices are required. Apparent electrical conductivity measured by electromagnetic induction instrument in a fairly quick manner has been widely used to estimate spatial soil salinity. However, methods used for this purpose are mostly a series of interpolation algorithms. In this study, sequential Gaussian simulation (SGS) and sequential Gaussian co-simulation (SGCS) algorithms were applied for assessing the prediction accuracy and uncertainty of soil salinity with apparent electrical conductivity as auxiliary variable. Results showed that the spatial patterns of soil salinity generated by SGS and SGCS algorithms showed consistency with the measured values. The profile distribution of soil salinity was characterized by increasing with depth with medium salinization (ECe 4–8 dS/m) as the predominant salinization class. SGCS algorithm privileged SGS algorithm with smaller root mean square error according to the generated realizations. In addition, SGCS algorithm had larger proportions of true values falling within probability intervals and narrower range of probability intervals than SGS algorithm. We concluded that SGCS algorithm had better performance in modeling local uncertainty and propagating spatial uncertainty. The inclusion of auxiliary variable contributed to prediction capability and uncertainty modeling when using densely auxiliary variable as the covariate to predict the sparse target variable. 相似文献
923.
Francis Douay Aurélie Pelfrêne Julie Planque Hervé Fourrier Antoine Richard Hélène Roussel Bertrand Girondelot 《Environmental monitoring and assessment》2013,185(5):3665-3680
Soil contamination by metals engenders important environmental and health problems in northern France where a smelter (Metaleurop Nord) was in activity for more than a century. This study aims to look at the long-term effects of the smelter after its closedown by combining data on the degree of soil contamination and the quality of the crops grown (agricultural crops and homegrown vegetables) in these soils for a better assessment of the local population’s exposure to Cd, Pb, and Zn. Seven years after the Metaleurop Nord closedown, (1) the agricultural and urban topsoils were strongly contaminated by Cd, Pb, and Zn; (2) the kitchen garden topsoils were even more polluted than the agricultural soils, with great variability in metal concentrations within the gardens studied; (3) a high proportion of the agricultural crops for foodstuffs did not conform with the European legislation; (4) for feedstuffs, most samples did not exceed the Cd and Pb legislation limits, indicating that feedstuffs may be an opportunity for most agricultural produce; and (5) a high proportion of the vegetables produced in the kitchen gardens did not conform with the European foodstuff legislation. The high contamination level of the soils studied continues to be a risk for the environment and the population’s health. A further investigation (part 2) assesses the associated potential health risk for local inhabitants through consumption of homegrown vegetables and ingestion of soil particles by estimating the site-specific human health assessment criteria for Cd and Pb. 相似文献
924.
Jürgens N Schmiedel U Haarmeyer DH Dengler J Finckh M Goetze D Gröngröft A Hahn K Koulibaly A Luther-Mosebach J Muche G Oldeland J Petersen A Porembski S Rutherford MC Schmidt M Sinsin B Strohbach BJ Thiombiano A Wittig R Zizka G 《Environmental monitoring and assessment》2012,184(2):655-678
The international, interdisciplinary biodiversity research project BIOTA AFRICA initiated a standardized biodiversity monitoring network along climatic gradients across the African continent. Due to an identified lack of adequate monitoring designs, BIOTA AFRICA developed and implemented the standardized BIOTA Biodiversity Observatories, that meet the following criteria (a) enable long-term monitoring of biodiversity, potential driving factors, and relevant indicators with adequate spatial and temporal resolution, (b) facilitate comparability of data generated within different ecosystems, (c) allow integration of many disciplines, (d) allow spatial up-scaling, and (e) be applicable within a network approach. A BIOTA Observatory encompasses an area of 1?km2 and is subdivided into 100 1-ha plots. For meeting the needs of sampling of different organism groups, the hectare plot is again subdivided into standardized subplots, whose sizes follow a geometric series. To allow for different sampling intensities but at the same time to characterize the whole square kilometer, the number of hectare plots to be sampled depends on the requirements of the respective discipline. A hierarchical ranking of the hectare plots ensures that all disciplines monitor as many hectare plots jointly as possible. The BIOTA Observatory design assures repeated, multidisciplinary standardized inventories of biodiversity and its environmental drivers, including options for spatial up- and downscaling and different sampling intensities. BIOTA Observatories have been installed along climatic and landscape gradients in Morocco, West Africa, and southern Africa. In regions with varying land use, several BIOTA Observatories are situated close to each other to analyze management effects. 相似文献
925.
Bradley S. Williams Ellen D’Amico Jude H. Kastens James H. Thorp Joseph E. Flotemersch Martin C. Thoms 《Environmental monitoring and assessment》2013,185(9):7485-7499
River systems consist of hydrogeomorphic patches (HPs) that emerge at multiple spatiotemporal scales. Functional process zones (FPZs) are HPs that exist at the river valley scale and are important strata for framing whole-watershed research questions and management plans. Hierarchical classification procedures aid in HP identification by grouping sections of river based on their hydrogeomorphic character; however, collecting data required for such procedures with field-based methods is often impractical. We developed a set of GIS-based tools that facilitate rapid, low cost riverine landscape characterization and FPZ classification. Our tools, termed RESonate, consist of a custom toolbox designed for ESRI ArcGIS®. RESonate automatically extracts 13 hydrogeomorphic variables from readily available geospatial datasets and datasets derived from modeling procedures. An advanced 2D flood model, FLDPLN, designed for MATLAB® is used to determine valley morphology by systematically flooding river networks. When used in conjunction with other modeling procedures, RESonate and FLDPLN can assess the character of large river networks quickly and at very low costs. Here we describe tool and model functions in addition to their benefits, limitations, and applications. 相似文献
926.
J. L. F. Angeli T. H. Trevizani A. Ribeiro E. C. Machado R. C. L. Figueira B. Markert S. Fraenzle S. Wuenschmann 《Environmental monitoring and assessment》2013,185(10):8333-8342
Concentrations of arsenic and four additional trace elements (Cu, Cr, Ni, and Zn) were determined by inductively coupled plasma–optical emission spectrometry in the muscular tissue of the yellow catfish (Cathorops spixii) and the urutu catfish (Genidens genidens) from Paranaguá Estuarine Complex, Brazil (PEC). The PEC can be characterized by an environment of high ecological and economic importance in which preserved areas of rainforest and mangroves coexist with urban activities as ports and industries. The average concentrations (in milligram per kilogram dry weight) of elements in the muscle tissue of C. spixii are as follows: Zn (31), As (17), Cu (1.17), Cr (0.62), and Ni (0.28). Similar concentrations could be found in G. genidens with exception of As: Zn (36), As (4.78), Cu (1.14), Cr (0.51), and Ni (0.14). Fish from the geographic northern rural region (Guaraqueçaba–Benito) display higher As concentrations in the muscle tissues than fish found in the south-western (urban) part of the PEC. An international comparison of muscle tissue concentrations of trace elements in fish was made. Except for Ni in C. spixii, a tendency of decrease in element concentration with increasing size (age) of the fish could be observed. According to the National Health Surveillance Agency of Brazil, levels of Cr and As exceeded the permissible limits for seafood. An estimation of the provisional tolerable weekly intake of As was calculated with 109 % for C. spixii and with 29 % for G. genidens. 相似文献
927.
Langston WJ O'Hara S Pope ND Davey M Shortridge E Imamura M Harino H Kim A Vane CH 《Environmental monitoring and assessment》2012,184(1):289-311
Biomonitoring of contaminants (metals, organotins, polyaromatic hydrocarbons (PAHs), PCBs) was undertaken in Milford Haven
Waterway (MHW) and a reference site in the Tywi Estuary (St Ishmael/Ferryside) during 2007–2008. Bioindicator species encompassed
various uptake routes—Fucus vesiculosus (dissolved contaminants); Littorina littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and Hediste (=Nereis) diversicolor (sediments). Differences in feeding and habitat preference have subtle implications for bioaccumulation trends though, with
few exceptions, contaminant burdens in MHW were higher than the Tywi reference site, reflecting inputs. Elevated metal concentrations
were observed at some MHW sites, whilst As and Se (molluscs and seaweed) were consistently at the higher end of the UK range.
However, for most metals, distributions in MH biota were not exceptional. Several metal-species combinations indicated increases
in bioavailability upstream, which may reflect the influence of geogenic/land-based sources—perhaps enhanced by lower salinity.
TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi were close to zero. Phenyltins were not accumulated
appreciably in M. edulis, whereas some H. diversicolor populations appear subjected to localized (historical) sources. PAHs in H. diversicolor were distributed evenly across most of MHW, although acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and chrysene were highest at one site near the mouth; naphthalenes in H. diversicolor were enriched in the mid-upper Haven (a pattern seen in M. edulis for most PAHs). Whilst PAH (and PCB) concentrations in MH mussels were mostly above reference and OSPAR backgrounds, they
are unlikely to exceed ecotoxicological thresholds. Bivalve Condition indices (CI) were highest at the Tywi reference site
and at the seaward end of MH, decreasing upstream—giving rise to several significant (negative) relationships between CI and
body burdens. Despite the possible influence of salinity gradient as a complicating factor, multivariate analysis indicated
that a combination of contaminants could influence the pattern in condition (and the biomarkers metallothionein and TOSC).
Integrating bioaccumulation data with biological and biochemical endpoints is seen as a useful way to discriminate environmental
quality of moderately contaminated areas such as MHW and to prioritise cause and effect investigations. 相似文献
928.
Drinking water samples collected from rural areas of three districts of Haryana during pre-monsoon and post-monsoon periods
were analysed for the presence of organochlorine pesticide residues. The main source of drinking water in rural areas, i.e.
groundwater in Ambala and Gurgaon districts and surface water supply in Hisar district, was found to be contaminated with
isomers of HCH and endosulfan and metabolites of DDT, whereas dieldrin remained below detection limits. During the study period,
the mean values observed for total HCH, DDT and endosulfan were 87.6, 848.2, and 27.4 ng/L and 99.8, 275.3 and 164.2 ng/L,
respectively, for Ambala and Gurgaon districts. In the case of Hisar district, the values were 78.5, 115.9, and 53.0 ng/L,
respectively. During the study period, 37% of the samples exceeded the total pesticide level of 500 ng/L indicated in the
EECD directive for drinking water. Seasonal variations of pesticide residues were also observed during the study period. 相似文献
929.
Vincent JH 《Journal of environmental monitoring : JEM》2012,14(2):340-347
This paper reviews how aerosol exposure assessment, for people in both working and living environments, has evolved over the years. It charts the main scientific developments that led to progressively improved ways of thinking and methods to assess exposure to airborne particulate matter in a manner more relevant to human health. It has been a long scientific journey as one generation of pioneering contributors has handed off to the next. In the process a consistent rationale has emerged, producing aerosol sampling criteria--and in turn exposure standards--which have been increasingly relevant to actual human exposures. The journey continues as a new generation of scientists steps up to deal with the new challenges that are emerging. An appreciation of the history of what went before is essential to charting the most effective path looking forward. 相似文献
930.
Inexact Fuzzy-Stochastic Programming for Water Resources Management Under Multiple Uncertainties 总被引:1,自引:0,他引:1
In this study, an interval-parameter fuzzy-stochastic two-stage programming (IFSTP) approach is developed for irrigation planning
within an agriculture system under multiple uncertainties. A concept of the distribution with fuzzy-interval probability (DFIP)
is defined to address multiple uncertainties expressed as integration of intervals, fuzzy sets, and probability distributions.
IFSTP integrates the interval programming, two-stage stochastic programming, and fuzzy-stochastic programming within a general
optimization framework. IFSTP incorporates the pre-regulated water resources management policies directly into its optimization
process to analyze various policy scenarios; each scenario has different economic penalty when the promised amounts are not
delivered. IFSTP is applied to an irrigation planning in a water resources management system. Solutions from IFSTP provide
desired water allocation patterns, which maximize both the system’s benefits and feasibility. The results indicate that reasonable
solutions are generated for objective function values and decision variables; thus, a number of decision alternatives can
be generated under different levels of stream flows. 相似文献