全文获取类型
收费全文 | 2801篇 |
免费 | 69篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 107篇 |
废物处理 | 118篇 |
环保管理 | 590篇 |
综合类 | 245篇 |
基础理论 | 847篇 |
环境理论 | 5篇 |
污染及防治 | 614篇 |
评价与监测 | 189篇 |
社会与环境 | 150篇 |
灾害及防治 | 30篇 |
出版年
2023年 | 13篇 |
2022年 | 33篇 |
2021年 | 42篇 |
2020年 | 39篇 |
2019年 | 41篇 |
2018年 | 63篇 |
2017年 | 60篇 |
2016年 | 95篇 |
2015年 | 80篇 |
2014年 | 82篇 |
2013年 | 253篇 |
2012年 | 104篇 |
2011年 | 187篇 |
2010年 | 116篇 |
2009年 | 144篇 |
2008年 | 157篇 |
2007年 | 162篇 |
2006年 | 131篇 |
2005年 | 106篇 |
2004年 | 92篇 |
2003年 | 94篇 |
2002年 | 78篇 |
2001年 | 54篇 |
2000年 | 41篇 |
1999年 | 45篇 |
1998年 | 33篇 |
1997年 | 34篇 |
1996年 | 38篇 |
1995年 | 46篇 |
1994年 | 37篇 |
1993年 | 33篇 |
1992年 | 28篇 |
1991年 | 33篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 13篇 |
1984年 | 28篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1978年 | 10篇 |
1977年 | 13篇 |
1975年 | 12篇 |
1974年 | 8篇 |
1971年 | 7篇 |
排序方式: 共有2895条查询结果,搜索用时 609 毫秒
821.
An uptake parameter u (L kg−1 d−1) and a loss rate parameter k (d−1) were estimated for the patterns of accumulation and loss of 133Cs by three fish species following an experimental 133Cs addition into a pond in South Carolina, USA. These u and k parameters were compared to similar estimates for fish from other experimental ponds and from lakes that received 137Cs deposition from Chernobyl. Estimates of u from ponds and lakes declined with increasing potassium concentrations in the water column. Although loss rates were greater in the experimental ponds, the times required to reach maximum Cs concentrations in fish were similar between ponds and lakes, because ponds and lakes had similar retentions of Cs in the water column. The maximum Cs concentrations in fish were largely determined by initial Cs concentrations in the water column. These maximum concentrations in fish and the times required to reach these maxima are potentially useful indicators for assessments of risks to humans from fish consumption. 相似文献
822.
P. B. L. Tamuno G. Howard M. D. Smith 《Environment, Development and Sustainability》2009,11(4):887-903
The Central Niger Delta is made up of a network of rivers and creeks that constitute the inland surface waters. These surface
waters have historically influenced settlement patterns and are of diverse use to residents of the Central Niger Delta. Surface
water like many ecological system are complex, whose complexity has been associated with seasonal variability. Traditional
knowledge (TK), traditional ecological knowledge (TEK) and the traditional eco-livelihood knowledge (TELK) of residents of
four rural communities in the Central Niger Delta have been explored in developing a river use profile of rural communities
of the Central Niger Delta. A questionnaire survey has been carried out in four communities, two each from the Otuoke and
Kolo Creeks. The result shows that river use varies across seasons and affected by: physico-chemical water quality and characteristics
of surface water; the hydrological characteristics; the biological/ecological characteristics; cultural use and demand; need
for development projects; and access to this vital resource. Fishing constitute one of the major livelihood source in the
Central Niger Delta and the TELK of fishers in the sample communities have specifically been explored to understanding fishing
patterns across seasons. The five seasons identified from this study are: flood season; flood recession season; dry season;
early rainy season; and rainy season. Therefore, the thesis of this paper is that there is the need to balance the current
usage of surface water in the developing world such as the Central Niger Delta with the demand for development as well as
future use if development is to meet the criteria for equitable development. The river use profile could be a promising tool
in planning for equitable development.
相似文献
M. D. SmithEmail: |
823.
Andrew O. Hughes Jon M. Olley Jacky C. Croke Ian T. Webster 《Journal of environmental radioactivity》2009,100(10):858-865
Fallout 137Cs has been widely used to determine floodplain sedimentation rates in temperate environments, particularly in the northern hemisphere. Its application in low fallout, tropical environments in the southern hemisphere has been limited. In this study we assess the utility of 137Cs for determining rates of floodplain sedimentation in a dry-tropical catchment in central Queensland, Australia. Floodplain and reference site cores were analysed in two centimetre increments, depth profiles were produced and total 137Cs inventories calculated from the detailed profile data. Information on the rates of 137Cs migration through local soils was obtained from the reference site soil cores. This data was used in an advection–diffusion model to account of 137Cs mobility in floodplain sediment cores. This allowed sedimentation rates to be determined without the first year of detection for 137Cs being known and without having to assume that 137Cs remains immobile following deposition. Caesium-137 depth profiles in this environment are demonstrated to be an effective way of determining floodplain sedimentation rates. The total 137Cs inventory approach was found to be less successful, with only one of the three sites analysed being in unequivocal agreement with the depth profile results. The input of sediment from catchment sources that have little, or no, 137Cs attached results in true depositional sites having total inventories that are not significantly different from those of undisturbed reference sites. 相似文献
824.
Fatin Samara Brian K. Gullett Robert O. Harrison Andrew Chu George C. Clark 《Environment international》2009,35(3):588-593
Determination of toxic activity requires knowledge of both the concentration and toxicity to evaluate the risk for adverse human health and environmental effects. A chemically-activated luciferase gene expression cell bioassay system (CALUX) and an antibody-based method enzyme immunoassay (EIA) were used to detect the dioxin-like response of several polybrominated, polychlorinated, and polybrominated/chlorinated dibenzo-p-dioxins/furans (PBDDs/Fs, PCDDs/Fs, and PBCDDs/Fs, respectively). It has been suggested that the biological activity of the brominated and mixed bromo/chloro compounds is similar to their chlorinated analogues (measured by binding to the Ah receptor). PBDD/F, PCDD/F, and PBCDD/F laboratory standards exhibited biological activity ranging over three orders of magnitude. The highest relative potency (REP) values from CALUX analysis, when compared to 2,3,7,8-TCDD, were 2,3,7,8-TBDD at 0.99 (± 0.07), 1,2,3,7,8-PeCDD at 0.69, and 2-Br-3,7,8-TriCDD at 0.72 (± 0.02). Cross-reactivities were calculated using EIA for several PBDDs/Fs and PBCDDs. The highest percent cross-reactivity was found for 2,3,7,8-TBDD at 138 (± 34%), and 2,3,7-TriBDD at 84 (± 36%). 相似文献
825.
Murphy JJ Dinar A Howitt RE Rassenti SJ Smith VL Weinberg M 《Journal of environmental management》2009,90(2):1089-1096
The main objective of this paper is to design and test a decentralized exchange mechanism that generates the location-specific pricing necessary to achieve efficient allocations in the presence of instream flow values. Although a market-oriented approach has the potential to improve upon traditional command and control regulations, questions remain about how these rights-based institutions can be implemented such that the potential gains from liberalized trade can be realized. This article uses laboratory experiments to test three different water market institutions designed to incorporate instream flow values into the allocation mechanism through active participation of an environmental trader. The smart, computer-coordinated market described herein offers the potential to significantly reduce coordination problems and transaction costs associated with finding mutually beneficial trades that satisfy environmental constraints. We find that direct environmental participation in the market can achieve highly efficient and stable outcomes, although the potential does exist for the environmental agent to influence outcomes. 相似文献
826.
Linking Theory and Practice for Restoration of Step-Pool Streams 总被引:1,自引:0,他引:1
Chin A Anderson S Collison A Ellis-Sugai BJ Haltiner JP Hogervorst JB Kondolf GM O'Hirok LS Purcell AH Riley AL Wohl E 《Environmental management》2009,43(4):645-661
Step-pools sequences are increasingly used to restore stream channels. This increase corresponds to significant advances in
theory for step-pools in recent years. The need for step-pools in stream restoration arises as urban development encroaches
into steep terrain in response to population pressures, as stream channels in lower-gradient areas require stabilization due
to hydrological alterations associated with land-use changes, and as step-pools are recognized for their potential to enhance
stream habitats. Despite an increasingly voluminous literature and great demand for restoration using step-pool sequences,
however, the link between theory and practice is limited. In this article, we present four unique cases of stream restoration
using step-pools, including the evolution of the approaches, the project designs, and adjustments in the system following
restoration. Baxter Creek in El Cerrito, California demonstrates an early application of artificial step-pools in which natural
adjustments occurred toward geomorphic stability and ecological improvement. Restoration of East Alamo Creek in a large residential
development near San Ramon, California illustrates an example of step-pools increasingly used in locations where such a channel
form would not naturally occur. Construction of a step-pool channel in Karnowsky Creek within the Siuslaw National Forest,
Oregon overcame constraints posed by access and the type and availability of materials; the placement of logs allowed natural
scouring below steps. Dry Canyon Creek on the property of the Mountains Restoration Trust in Calabasas, California afforded
a somewhat experimental approach to designing step-pools, allowing observation and learning in the future. These cases demonstrate
how theories and relationships developed for step-pool sequences over the past two decades have been applied in real-world
settings. The lessons from these examples enable us to develop considerations useful for deriving an appropriate course of
design, approval, and construction of artificial step-pool systems. They also raise additional fundamental questions concerning
appropriate strategies for restoration of step-pool streams. Outstanding challenges are highlighted as opportunities for continuing
theoretical work. 相似文献
827.
Environmental integrated assessments are often carried out via the aggregation of a set of environmental indicators. Aggregated
indices derived from the same data set can differ substantially depending upon how the indicators are weighted and aggregated,
which is often a subjective matter. This article presents a method of generating aggregated environmental indices in an objective
manner via Monte Carlo simulation. Rankings derived from the aggregated indices within and between three Monte Carlo simulations
were used to evaluate the overall environmental condition of the study area. Other insights, such as the distribution of good
or bad values of indicators at a watershed and/or a subregion, were observed in the study. 相似文献
828.
It has been argued that strategies to manage natural areas important for tourism and recreation should integrate an understanding
of tourist preferences for specific natural features. However, the accuracy of tourist recalled perceptions of environmental
attributes, which are usually derived from post hoc surveys and used to establish management priorities, is currently unmeasured.
We tested the validity of the relationship between tourist-stated preferences and actual condition of coral reefs around the
Caribbean island of Bonaire. Using standardized questionnaires, we asked 200 divers to select their most and least favorite
dive sites and the attributes that contributed to that selection. We also carried out ecological surveys at 76 of the 81 dives
sites around the island to assess the actual conditions of the attributes indicated as important for site selection. Fish-
and coral-related attributes were key features affecting dive enjoyment. In general, divers appeared to be able to perceive
differences between sites in the true condition of biological attributes such as fish species richness, total number of fish
schools, live coral cover, coral species richness, and reef structural complexity, although men and women divers differed
in their ability to perceive/recall some of the attributes. Perceived differences in environmental attributes, such as surface
conditions, underwater current, and the likelihood of encountering rare fish and sea turtles, were not empirically validated.
The fact that divers perceive correctly differences in the condition of some of the key biological attributes that affect
dive enjoyment reinforces the need to maintain overall reef condition at satisfactory levels. However, variation in accuracy
of perceptions owing to demographic factors and attribute type suggests the need for caution when using public perceptions
to develop environmental management strategies, particularly for coral reefs. 相似文献
829.
Most studies characterizing successful biological invaders emphasize those traits that help a species establish a new population.
Invasions are, however, multi-phase processes with at least two phases, dispersal and introduction, that occur before establishment.
Characteristics that enhance survival at any of these three phases will contribute to invasion success. Here, we synthesize
information on the dispersal, introduction, and establishment of fishes mediated by ship ballast-water transport. We synthesize
54 reports of at least 31 fish species collected from ballast tanks (Phase 1), including 28 new reports from our recent studies
(1986 to 1996). Our literature survey revealed 40 reports of 32 fish species whose introductions have been attributed to ballast
transport (Phase 2), of which at least 24 survived to establish persistent populations (Phase 3). We detected little overlap
at the species level between these two data sets (Phase 1 vs Phases 2 and 3), but patterns emerged at the family level. The
Gobiidae (6 species), Clupeidae (4 species), and Gasterosteidae (1 species) were the most commonly found fish families in
ballast tanks (Phase 1). The Gobiidae (13 species), Blenniidae (6 species) and Pleuronectidae (2 species) dominated the list
of ballast-mediated introductions (Phase 2); gobies and blennies were the families most frequently established (Phase 3).
The invasive success of gobies and blennies may be explained in part by their crevicolous nature: both groups seek refuge
and lay eggs in small holes, and may take advantage of the ballast-intake holes on ship hulls. This behavior, not typically
associated with invasive ability, may contribute to successful introduction and establishment by facilitating the dispersal
phase of invasion. The failure of the pleuronectids to invade may reflect poor salinity match between donor and recipient
regions. To develop a predictive framework of invasion success, organisms must be sampled at all three phases of the invasion
process. Our comparison of two ballast sampling methods suggests that fishes have been undersampled in ballast-water studies,
including our own, and that the role of ballast transport in promoting fish invasions has been underestimated.
Received: 13 January 1999 / Accepted: 24 February 2000 相似文献
830.
Robert K. Hall Gary A. Wolinsky Peter Husby James Harrington Patti Spindler Karen Vargas Gordon Smith 《Environmental monitoring and assessment》2000,64(1):17-30
U.S. EPA Region IX is supporting bioassessment programs in Arizona, California, Hawaii and Nevada using biocriteria program and Regional Environmental Monitoring and Assessment Program (R-EMAP) resources. These programs are designed to improve the state, tribal and regional ability to determine the status of water quality. Biocriteria program funds were used to coordinate with Arizona, California and Hawaii which resulted in these states establishing reference conditions and in developing biological indices. U.S. EPA Region IX has initiated R-EMAP projects in California and Nevada. These U.S. EPA Region IX sponsored programs have provided an opportunity to interact with the States and provide them with technical and management support. In Arizona, several projects are being conducted to develop the State's bioassessment program. These include the development of a rotational random monitoring program; a regional reference approach for macroinvertebrate bioassessments; ecoregion approach to testing and adoption of an alternate regional classification system; and development of warm-water and cold-water indices of biological integrity. The indices are projected to be used in the Arizona Department of Environmental Quality (ADEQ) 2000 water quality assessment report. In California, an Index of Biological Integrity (IBI) has been developed for the Russian River Watershed using resources from U.S. EPA's Non-point Source (NPS) Program grants. A regional IBI is under development for certain water bodies in the San Diego Regional Water Quality Control Board. Resources from the U.S. EPA Biocriteria program are being used to support the California Aquatic Bioassessment Workgroup (CABW) in conjunction with the California Department of Fish & Game (CDFG), and to support the Hawaii Department of Health (DoH) Bioassessment Program to refine biological metrics. In Nevada, R-EMAP resources are being used to create a baseline of aquatic information for the Humboldt River watershed. U.S. EPA Region IX is presently working with the Nevada Division of Environmental Protection (NDEP) to establish a Nevada Aquatic Bioassessment Workgroup. Future R-EMAP studies will occur in the Calleguas Creek watershed in Southern California, and in the Muddy and Virgin River watersheds in southern Nevada, and the Walker River watershed in eastern California and west-central Nevada. 相似文献