全文获取类型
收费全文 | 1279篇 |
免费 | 23篇 |
国内免费 | 27篇 |
专业分类
安全科学 | 49篇 |
废物处理 | 41篇 |
环保管理 | 272篇 |
综合类 | 154篇 |
基础理论 | 293篇 |
环境理论 | 2篇 |
污染及防治 | 387篇 |
评价与监测 | 82篇 |
社会与环境 | 42篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 13篇 |
2022年 | 17篇 |
2021年 | 23篇 |
2020年 | 6篇 |
2019年 | 24篇 |
2018年 | 29篇 |
2017年 | 34篇 |
2016年 | 39篇 |
2015年 | 26篇 |
2014年 | 41篇 |
2013年 | 189篇 |
2012年 | 53篇 |
2011年 | 58篇 |
2010年 | 60篇 |
2009年 | 70篇 |
2008年 | 55篇 |
2007年 | 72篇 |
2006年 | 78篇 |
2005年 | 44篇 |
2004年 | 40篇 |
2003年 | 38篇 |
2002年 | 41篇 |
2001年 | 8篇 |
2000年 | 19篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 17篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1972年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有1329条查询结果,搜索用时 15 毫秒
101.
George E. Radosevich Melvin B. Sabey 《Journal of the American Water Resources Association》1977,13(4):747-757
ABSTRACT: Faced with the necessity of meeting growing municipal water requirements in areas where available supplies are completely allocated, numerous cities throughout the West are turning to their eminent domain powers to affect a reallocation of water from less preferred uses to municipal uses, thus bringing about a sharp conflict with agricultural interests. As a basis for discussing these eminent domain powers, this paper begins with a brief review of the development of property rights. The existence of both private and public (social) rights in the “bundle of rights” is noted. In recent years the Public Trust Doctrine has been used to limit private rights in property, and to protect and strengthen social rights. A case study which focuses on a conflict between individual and social interests in water rights is discussed. This case involves the City of Thorton, Colorado which initiated municipal condemnation proceedings to acquire the water rights and structures of two nearby irrigation companies. The case represents an attempt to incorporate the spirit of the Public Trust Doctrine into legislation which sets forth procedures for resolution of similar water rights conflicts that will inevitably become more numerous throughout the West in the future. 相似文献
102.
103.
Goris Nazari Joy C. MacDermid Kathryn E. Sinden Tom J. Overend 《International journal of occupational safety and ergonomics》2019,25(1):1-7
Introduction. Few studies have addressed whether firefighters are fitter than the general population and possess sufficient levels of aerobic capacity and muscle strength to perform on-duty tasks in a safe and efficient manner, considering age and gender. We aimed to evaluate the fitness levels of Hamilton firefighters, and to determine the effects of age and gender. Methods. In total, 89 participants were recruited. The modified Canadian aerobic fitness test was used to determine participants’ estimated maximal oxygen consumption (VO2max) levels. For upper and lower body strength levels, a calibrated J-Tech hand-held dynamometer and a National Institute for Occupational Safety and Health (NIOSH) lifting device was used respectively. Results. Firefighters’ mean (SD) VO2max level was 40.30?±?6.25?ml·kg?1·min?1. Age proved to have a statistically significant impact on VO2max (p?<?0.001). Gender displayed statistically significant effects on strength levels. Firefighters’ age was the only statistically significant independent variable, and accounted for 61.00% of the variance in firefighters’ aerobic capacity levels. Conclusions. Firefighters possessed somewhat similar aerobic capacities but much higher levels of body strength when compared with the general population. With age, firefighters’ aerobic capacities decreased; however, their upper and lower body strength levels remained the same. 相似文献
104.
Kathryn A. Powlen Jonathan Salerno Kelly W. Jones Michael C. Gavin 《Conservation biology》2023,37(4):e14058
Protected areas (PAs) are a commonly used strategy to confront forest conversion and biodiversity loss. Although determining drivers of forest loss is central to conservation success, understanding of them is limited by conventional modeling assumptions. We used random forest regression to evaluate potential drivers of deforestation in PAs in Mexico, while accounting for nonlinear relationships and higher order interactions underlying deforestation processes. Socioeconomic drivers (e.g., road density, human population density) and underlying biophysical conditions (e.g., precipitation, distance to water, elevation, slope) were stronger predictors of forest loss than PA characteristics, such as age, type, and management effectiveness. Within PA characteristics, variables reflecting collaborative and equitable management and PA size were the strongest predictors of forest loss, albeit with less explanatory power than socioeconomic and biophysical variables. In contrast to previously used methods, which typically have been based on the assumption of linear relationships, we found that the associations between most predictors and forest loss are nonlinear. Our results can inform decisions on the allocation of PA resources by strengthening management in PAs with the highest risk of deforestation and help preemptively protect key biodiversity areas that may be vulnerable to deforestation in the future. 相似文献
105.
Mahdi Ahmadi Josh Minot George Allen Lisa Rector 《Journal of the Air & Waste Management Association (1995)》2020,70(4):393-409
ABSTRACTA study was undertaken to identify patterns of consumer use of outdoor wood boilers or outdoor wood furnaces (technically referred to as outdoor wood-fired hydronic heaters (OWHHs)) and indoor wood stoves (IWSs) to inform the development of performance testing protocols that reflect real-life operating conditions. These devices are manually fed, and their usage protocols are a function of a number of variables, including user habits, household characteristics, and environmental factors. In this study, researchers logged the stack wall temperatures of 4 OWHH and 20 IWS units in the states of New York and Washington over two heating seasons. Stack wall temperature is an indicator of changes in combustion modes. Two algorithms were developed to identify usage modes and cold and warm start refueling events from the stack wall temperature time series. A linear correlation analysis was conducted to evaluate the effect of heat demand on usage patterns. The results and methods presented here will inform the cataloging of typical operational patterns of OWHHs and IWSs as a step in the development of performance testing procedures that represent actual in-home usage patterns.Implications: Current US regulatory programs for residential wood heating use a certification program to assess emissions and efficiency performance. Testing under this program uses a test that burns 100% of a single, standardized wood fuel charge to assess performance at different steady-state load conditions. This study assessed in-field operational patterns to determine if the current certification approach accurately characterized typical homeowner use patterns. The data from this study can be used to inform revisions to testing methods to increase certification test comparability between lab and field performance. 相似文献
106.
Brian E. Reichert Mylea Bayless Tina L. Cheng Jeremy T. H. Coleman Charles M. Francis Winifred F. Frick Benjamin S. Gotthold Kathryn M. Irvine Cori Lausen Han Li Susan C. Loeb Jonathan D. Reichard Thomas J. Rodhouse Jordi L. Segers Jeremy L. Siemers Wayne E. Thogmartin Theodore J. Weller 《Ambio》2021,50(4):901
Collaborative monitoring over broad scales and levels of ecological organization can inform conservation efforts necessary to address the contemporary biodiversity crisis. An important challenge to collaborative monitoring is motivating local engagement with enough buy-in from stakeholders while providing adequate top-down direction for scientific rigor, quality control, and coordination. Collaborative monitoring must reconcile this inherent tension between top-down control and bottom-up engagement. Highly mobile and cryptic taxa, such as bats, present a particularly acute challenge. Given their scale of movement, complex life histories, and rapidly expanding threats, understanding population trends of bats requires coordinated broad-scale collaborative monitoring. The North American Bat Monitoring Program (NABat) reconciles top-down, bottom-up tension with a hierarchical master sample survey design, integrated data analysis, dynamic data curation, regional monitoring hubs, and knowledge delivery through web-based infrastructure. NABat supports collaborative monitoring across spatial and organizational scales and the full annual lifecycle of bats. 相似文献
107.
Optimum conditions for microbial carbonate precipitation 总被引:3,自引:0,他引:3
The type of bacteria, bacterial cell concentration, initial urea concentration, reaction temperature, the initial Ca(2+) concentration, ionic strength, and the pH of the media are some factors that control the activity of the urease enzyme, and may have a significant impact on microbial carbonate precipitation (MCP). Factorial experiments were designed based on these factors to determine the optimum conditions that take into consideration economic advantage while at the same time giving quality results. Sporosarcina pasteurii strain ATCC 11859 was used at constant temperature (25°C) and ionic strength with varying amounts of urea, Ca(2+), and bacterial cell concentration. The results indicate that the rate of ureolysis (k(urea)) increases with bacterial cell concentration, and the bacterial cell concentration had a greater influence on k(urea) than initial urea concentration. At 25 mM Ca(2+) concentration, increasing bacterial cell concentration from 10(6) to 10(8)cells mL?1 increased the CaCO(3) precipitated and CO(2) sequestrated by over 30%. However, when the Ca(2+) concentration was increased 10-fold to 250 mM Ca(2+), the amount of CaCO(3) precipitated and CO(2) sequestrated increased by over 100% irrespective of initial urea concentration. Consequently, the optimum conditions for MCP under our experimental conditions were 666 mM urea and 250 mM Ca(2+) at 2.3×10? cells mL?1 bacterial cell concentration. However, a greater CaCO(3) deposition is achievable with higher concentrations of urea, Ca(2+), and bacterial cells so long as the respective quantities are within their economic advantage. X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray analyzes confirmed that the precipitate formed was CaCO(3) and composed of predominantly calcite crystals with little vaterite crystals. 相似文献
108.
George F. Antonious John C. Snyder Terry Berke Robert L. Jarret 《Journal of environmental science and health. Part. B》2013,48(6):562-571
Elevated concentrations of heavy metals in edible plants could expose consumers to excessive levels of potentially hazardous chemicals. Sixty-three accessions (genotypes) of Capsicum chinense Jacq, collected from 8 countries of origin were grown in a silty-loam soil under field conditions. At maturity, fruits were collected and analyzed for seven heavy metals (Cd, Cr, Ni, Pb, Zn, Cu, and Mo) concentrations. The main objectives of this investigation were: 1) to determine the concentrations of seven heavy metals in the soil and monitor their accumulation in mature fruits, 2) to categorize the pepper accessions as low or high heavy metal accumulators, and 3) to determine if heavy metal content of the pepper fruit was lower than the permitted limits. Concentrations and relative proportions of heavy metals in pepper fruits of C. chinense varied among accessions. Fruits of Plant Introduction (PI) 355820 accumulated significant concentrations of Cd (0.47 μ g g?1dry fruit). PI-260522 accumulated the highest concentration of Pb (2.12 μ g g?1 dry fruit) among the 63 accessions tested. This accession (PI-260522) contained about twice the Pb limit on a fresh weight basis. Among the 63 accessions analyzed, PI-238051 contained the highest levels of Ni (17.2 μ g g?1). We concluded that high accumulator genotypes may be useful for phytoremediation, while, low accumulator accessions might be appropriate selections for growing on Cd-, Pb-, or Ni-contaminated soils to prevent potential human exposure to heavy metals and health hazards through the food chain. 相似文献
109.
Graphical models provide an important tool for facilitating communication between scientists, decision-makers, and statisticians—many
complicated ecological processes can be described in terms of “box-and-arrow” conceptual diagrams (e.g., Shipley in Cause
and correlation in biology: a user’s guide to path analysis, structural equations and causal inferences, Cambridge Universtiy
Press, Cambridge, 2000; Clark and Gelfand TRENDS in Ecology and Evolution 21:375–380, 2006). In particular, problems in landscape
ecology often involve modeling relationships among multiple physical and/or biological variables that may operate on differing
spatial scales (e.g., Rossi et al. in Ecol Monographs 62:277–314, 1992; Legendre et al. in Ecography 25:601–615, 2002; Overmars
et al. in Ecol Model 164:257–270, 2003; Brown and Spector in J Appl Ecol 45:1639–1648, 2008; Koniak and Noy-Meir in Ecol Model
220:1148–1158, 2008). These problems are inherently multivariate, though researchers commonly rely on univariate methods,
such as spatial regression models, to address them. In this paper, we introduce a multivariate method—graphical spatial models—that
extends path analysis to incorporate spatial autocorrelation in one or more variables in a directed graph. We show how both
exogenous and endogenous ecological processes as defined by Legendre et al. (Ecography 25:601–615, 2002) and Lichstein et al.
(Ecol Monographs 72:445–463, 2002) can be represented in a graph. Most importantly, we show how to translate graphs representing
these ecological processes into statistically estimable models. We motivate our theoretical results using an example of stream
health data from the Willamette Valley, Oregon. For these data we are interested in the spatial pattern within both riparian
land use and an index of stream health, and whether there is an association between land use and stream health, after accounting
for these spatial patterns. We use a graphical spatial model to address these ecological questions simultaneously. We find
that the health of a stream decreases as the percent of developed land within a 120-m riparian buffer increases; interestingly,
there is only evidence of spatial pattern within land use. 相似文献
110.
John E. Hobbie Gaius R. Shaver Edward B. Rastetter Jessica E. Cherry Scott J. Goetz Kevin C. Guay William A. Gould George W. Kling 《Ambio》2017,46(1):160-173
Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness. 相似文献