全文获取类型
收费全文 | 31114篇 |
免费 | 233篇 |
国内免费 | 367篇 |
专业分类
安全科学 | 512篇 |
废物处理 | 1706篇 |
环保管理 | 3694篇 |
综合类 | 4528篇 |
基础理论 | 8793篇 |
环境理论 | 4篇 |
污染及防治 | 7257篇 |
评价与监测 | 2486篇 |
社会与环境 | 2599篇 |
灾害及防治 | 135篇 |
出版年
2022年 | 241篇 |
2021年 | 198篇 |
2020年 | 159篇 |
2019年 | 199篇 |
2018年 | 1702篇 |
2017年 | 1641篇 |
2016年 | 1624篇 |
2015年 | 503篇 |
2014年 | 657篇 |
2013年 | 1796篇 |
2012年 | 1139篇 |
2011年 | 2229篇 |
2010年 | 1501篇 |
2009年 | 1411篇 |
2008年 | 1811篇 |
2007年 | 2160篇 |
2006年 | 852篇 |
2005年 | 777篇 |
2004年 | 780篇 |
2003年 | 785篇 |
2002年 | 789篇 |
2001年 | 939篇 |
2000年 | 655篇 |
1999年 | 347篇 |
1998年 | 247篇 |
1997年 | 276篇 |
1996年 | 293篇 |
1995年 | 344篇 |
1994年 | 306篇 |
1993年 | 254篇 |
1992年 | 267篇 |
1991年 | 252篇 |
1990年 | 272篇 |
1989年 | 243篇 |
1988年 | 212篇 |
1987年 | 226篇 |
1986年 | 201篇 |
1985年 | 208篇 |
1984年 | 210篇 |
1983年 | 198篇 |
1982年 | 177篇 |
1981年 | 178篇 |
1980年 | 157篇 |
1979年 | 169篇 |
1978年 | 130篇 |
1977年 | 143篇 |
1975年 | 117篇 |
1974年 | 116篇 |
1973年 | 133篇 |
1972年 | 128篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
171.
172.
Quevauviller P 《Journal of environmental monitoring : JEM》1999,1(3):48N-49N
Following the decision of the European Parliament and of the Council of 22 December 1998, The European Commission has launched its Fifth Framework Programme for Research, Technological Development and Demonstration (RTD) which will run from 1999 to 2002. The activities will be carried out in the frame of four thematic programmes and three horizontal ones. The first calls for proposals were published in March 1999. Detailed information on the work programme of each activity is available through the Internet at the following address http://www.cordis.lu/fp5 and through direct contact with the programme's help-desks. The present summary gives an outline of environment-related research activities covered by 5th FWP. 相似文献
173.
Kramer KJ Dorten WS van het Groenewoud H de Haan E Kramer GN Monteiro L Muntau H Quevauviller P 《Journal of environmental monitoring : JEM》1999,1(1):83-89
In order to control the quality of rare earth determinations in environmental matrices, the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna muscle, mussel tissue, aquatic plant and estuarine sediment) for their contents of a range of rare earth elements (Sc, Y and the lanthanides: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The elements U and Th were added to the study. The first part of this project consisted of an interlaboratory study which aimed to test the feasibility of preparation of environmental reference materials and to detect and remove most of the pitfalls observed in rare earth determinations. This paper presents the preparation of the four matrices for the intercomparison study and for the candidate reference material. The main results are presented of the interlaboratory study that was carried out prior to the certification campaign. This collaborative trial is the first attempt ever carried out at this scale to evaluate the state-of-the-art of rare earth determinations in the environment. Its impact on the improvement of chemical measurements will have positive effects on the comparability of data necessary for environmental monitoring. 相似文献
174.
MARTIN A. STAPANIAN STEVEN P. CLINE DAVID L. CASSELL 《Environmental monitoring and assessment》1997,45(3):237-257
We evaluate a field method for determining species richness andcanopy cover of vascular plants for the Forest Health MonitoringProgram (FHM), an ecological survey of U.S. forests. Measurementsare taken within 12 1-m2 quadrats on 1/15 ha plots in FHM.Species richness and cover are determined for four height classes(strata) within each quadrat and aggregated by stratum over the entireplot. We estimated (1) the agreement between experienced trainers andinexperienced technicians who collected the data on this survey(accuracy) and (2) the agreement among the technicians (precision) forresults on species richness and cover from 3 test plots at 3 timeintervals. The methods appear to be highly precise, although somediscrepancies with the values obtained by the trainers were found.Trainers found significantly more species in the ground stratum (0–0.6 m) and measured significantly more cover in the uppermost stratum(>4.9 m). The proportion of variation due to measurement error andtemporal variability was less than 13% for species richness (all strata)and cover (all but one stratum). This indicates that the method issuitable for monitoring changes in species richness and canopy coverfor a large-scale synoptic monitoring project such as FHM. 相似文献
175.
D. M. Whelpdale P. W. Summers E. Sanhueza 《Environmental monitoring and assessment》1997,48(3):217-247
This paper presents a summary of globalacid deposition flux data taken from a globalassessment report on acid deposition prepared forUNEP/WMO (Whelpdale and Kaiser, 1996). There is a largevariation in the spacial coverage and reliability ofmonitoring around the world. Many more stationsmeasure wet deposition than collect appropriate datafor estimating dry deposition. The widespread regionswith highest precipitation concentrations anddeposition fluxes of sulphate and nitrate coincideclosely with the regions of highest density ofSO2 and NOx precursor emissions occurringprimarily in the mid-latitude, northern hemispherebelt where a large fraction of the worlds fossilfuels is consumed. Organic acids in precipitation makea minor contribution to acidity (<20%) inindustrial regions, but in the rest of the world theyare of same order, or even exceed, inorganic acids.Less is known about dry deposition, but it appears topredominate near strong emission sources with wetdeposition predominating farther downwind. The molarratio of the N/S contribution to acidic deposition isclose to 1.0 over large areas of Europe and NorthAmerica, but is highly variable elsewhere, beinghighest in equatorial regions due to biomass burningand lowest near smelters and other large sources of SO2. 相似文献
176.
Modeling rhizofiltration: heavy-metal uptake by plant roots 总被引:1,自引:0,他引:1
P. Verma K. V. George H. V. Singh S. K. Singh A. Juwarkar R. N. Singh 《Environmental Modeling and Assessment》2006,11(4):387-394
The discovery of phytoaccumulation potential of plant species has led to its application for remediation of heavy-metal-contaminated soil and wastewater, which is termed as phytoextraction/rhizofiltration. For prediction, analysis, planning and cost-effective design of such systems, mathematical models not only are used as a screening tool but also provide optimal parameters like harvesting time, irrigation schedule, etc. Several laboratory and field scale studies have been carried out in the past, and mathematical expressions have been developed by various researchers for different phenomena like metal adsorption in soil, plant root growth with time, moisture and metal uptake by plant root, moisture movement in unsaturated zone, soil moisture relationship, etc. The complete design of any such phytoremediation program would require the knowledge of behavior of heavy-metal movement in soil, water and plant root system. In this paper, a model for simulating heavy-metal dynamics in soil, water and plant root system is developed and discussed. The governing non-linear partial differential equation is solved numerically by implicit finite difference method using Picard's iterative technique, and the formulation has been illustrated using a characteristic example. The source code is written in MATLAB. 相似文献
177.
Gottfried Tappeiner Ulrike Tappeiner Janette Walde 《Environmental Modeling and Assessment》2007,12(4):253-256
The complexity of today’s research problems increasingly demands that scientists move beyond the confines of their own discipline.
In this special issue, the basics of a transdisciplinary framework are established and problems analyzed in a specific discipline
are successfully integrated in this transdisciplinary network. The intent has been to go beyond only statements about the
importance of enabling early stage researchers to work across disciplinary boundaries, and to show that important discoveries
are being made at the intersection of disciplines. Embedding various research projects in a more global framework can meet
the demands of an interdisciplinary or transdisciplinary approach (especially for early stage researchers) and contribute
significantly to sustainable research. 相似文献
178.
A study on the orbit of air temperature movement 总被引:1,自引:0,他引:1
Zong-Chang Yang 《Environmental Modeling and Assessment》2007,12(2):131-143
In this paper, we describe an air temperature movement by mapping its time series to the polar coordinates: the value of the
time series is plotted on the radial coordinate and the time on the angular coordinate. In this way, both the yearly and daily
air temperature movements from five different locations of China are used to demonstrate that, in an intuitionistic view,
air temperature movement is neither random nor chaotic, but has its own orbit. We then propose an elliptic orbit model for
the air temperature movement. Our proposed model provides quite good results when it is applied to the evaluation of yearly
air temperature movements in eight locations in various parts of the world, and the evaluation of daily air temperature movements
in five locations in Hunan Province of China on December 17, 2005. Results show that our approach provides a concise and helpful
model for air temperature analysis. 相似文献
179.
R. A. Field J. R. Brown M. E. Goldstone J. N. Lester R. Perry 《Environmental monitoring and assessment》1996,43(2):101-116
Results of intermittent monitoring of six aromatic hydrocarbons (benzene, toluene, ethyl-benzene, m-xylene, p-xylene and o-xylene), carbon monoxide and oxides of nitrogen over a thirteen year period at a site in central London (Exhibition Road) are presented. Four monitoring regimes were undertaken; namely, 1979, 1982/83, 1986/87 and 1991/92. The summertime daytime mean ambient concentrations of the measured parameters at this site are presented. The reported concentrations show a reduction from 1979 to 1992 by approximately a factor of two, despite national increases in motor fuel consumption and the volume of traffic. Relevant European Community legislation covering emissions from motor-vehicles are outlined and comparisons are made with emissions from motor vehicles predicted from the UK national inventory. The importance of the frequency of measurements was also noted. 相似文献
180.
During the summers of 1991–1994, the Environmental Monitoringand Assessment Program (EMAP) sampled 344 lakes throughout thenortheastern United States using a proportional stratified sampling design based on lake size. Approximately one-quarter ofthe 344 lakes were sampled each year (4 years) for totalphosphorus to determine the proportion (and associated95% confidence intervals) of the northeast lake population 1ha (11,076 ± 1,699 lakes) that was in oligotrophic,mesotrophic, eutrophic, or heupereutropic (4 classes) conditionaccording to the total phosphorus criteria of the North AmericaLake Manegement Society. Estimates for the second, third, andfourth yr were developed as cumulative of the previous yrsamples and the current yr samples for the northeast as a wholeand for each of its three ecoregions (4 regions). New confidence intervals were computed for each cumulative yrcondition estimate. This produced a total (4 years × 4classes × 4 regions) of 64 cumulative yr tropic conditionestimates. Confidence intervals for 21% of these estimates didnot shorten with increased sample size. This phenomena raisedquestions about the accuracy of estimates based on cumulativesampling procedures. We explain why and how the phenomenon comesabout with both straight random and proportional randomsampling. Further, we present an example of the effects thisphenomenon has on lake tropic state condition estimates in thenortheastern United States. 相似文献