全文获取类型
收费全文 | 416篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 14篇 |
环保管理 | 119篇 |
综合类 | 40篇 |
基础理论 | 80篇 |
环境理论 | 2篇 |
污染及防治 | 85篇 |
评价与监测 | 37篇 |
社会与环境 | 13篇 |
灾害及防治 | 2篇 |
出版年
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 39篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 19篇 |
2007年 | 19篇 |
2006年 | 8篇 |
2005年 | 17篇 |
2004年 | 6篇 |
2003年 | 14篇 |
2002年 | 17篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1957年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 171 毫秒
321.
322.
Obligate Cave Fauna of the 48 Contiguous United States 总被引:7,自引:0,他引:7
David C. Culver Lawrence L. Master † Mary C. Christman ‡ and Horton H. Hobbs III § 《Conservation biology》2000,14(2):386-401
Abstract: We assembled a list of obligate cave-dwelling species and subspecies, their county distribution, and their provisional global conservation rank. A total of 927 species and 46 additional subspecies in 96 families exclusively from cave and associated subterranean habitats have been described in the 48 contiguous states of the United States. The terrestrial (troglobitic) species are concentrated in northeast Alabama (especially Jackson County), with other concentrations in Kentucky, Texas, Virginia, and West Virginia. Only 23 counties, comprising less than 1% of the land area of the 48 contiguous states, account for over 50% of the terrestrial species and subspecies. The aquatic (stygobitic) species are concentrated in Hays County, Texas, with other concentrations in Florida, Oklahoma, Texas, Virginia, and West Virginia. Only 18 counties, comprising less than 1% of the land area, account for over 50% of the aquatic species and subspecies. Endemism is high, with 54% of the species known from a single county. Approximately 95% of the species are listed by The Nature Conservancy as vulnerable or imperiled in the United States. These cave species comprise 50% of all vulnerable or imperiled species listed in databases of the Natural Heritage Program. Less than 4% of these subterranean species have federal status. Conservation can best be accomplished through habitat protection, which must include protection of the associated surface habitat. 相似文献
323.
324.
Ilias G. Kavouras Joy Lawrence Petros Koutrakis Euripides G. Stephanou Pedro Oyola 《Atmospheric environment (Oxford, England : 1994)》1999,33(30):1588
Using a novel sampler, particulate organic compounds were collected in Santiago de Chile from June 9 to August 10, 1997. This sampler consists of a diffusion denuder to remove gas-phase organics prior to particle collection, a Teflon filter, and a PUF cartridge downstream of the filter. PAHs and n-alkanes were measured using gas chromatography/mass spectrometry analysis. Volatilization of particles collected on the Teflon filter varied from 15 to 85% for both n-alkanes and PAHs, with strong dependence on molecular weight. The relative distribution of n-alkanes and the values of molecular diagnostic ratios, such as Carbon preference index, indicated a mixed origin with strong anthropogenic input. Indeed, CPI values ranged from 0.66 to 1.96 (for the whole range of n-alkanes). The percent contribution of leaf “wax” n-alkanes (4.55–20.83%) indicated the low contribution of biogenic sources. In addition, the distribution pattern of PAHs was characteristic of anthropogenic emissions. The dominant contribution of combustion-related PAHs (CPAHs), 74–84%, indicated that vehicular emissions was the major source of PAHs. 相似文献
325.
Relationships Between Landscape Characteristics and Nonpoint Source Pollution Inputs to Coastal Estuaries 总被引:24,自引:0,他引:24
The model can help in examining the relative sensitivity of water-quality variables to alterations in land use made at varying
distances from the stream channel. The model also shows the importance of streamside management zones, which are key to maintenance
of stream water quality. The linkage model can be considered a first step in the integration of GIS and ecological models.
The model can then be used by local and regional land managers in the formulation of plans for watershed-level management. 相似文献
326.
Given the common use of self‐ratings and other‐ratings (e.g., supervisor or coworker) of organizational citizenship behavior (OCB), the purpose of this meta‐analysis was to evaluate the extent to which these rating sources provide comparable information. The current study's results provided three important lines of evidence supporting the use and construct‐related validity of self‐rated OCB. The meta‐analysis of mean differences demonstrated that the mean difference in OCB ratings is actually quite small between self‐ and other‐raters. Importantly, the difference between self‐ and other‐raters was influenced by neither the response scale (i.e., agreement vs. frequency) nor the use of antithetical/reverse‐worded items on OCB scales. The meta‐analysis of correlations showed that self‐ and other‐ratings are moderately correlated but that self–other convergence is higher when antithetical items are not used and when agreement response scales are used. In addition, self‐ratings and supervisor‐ratings showed significantly more convergence than self‐ratings and coworker‐ratings. Finally, an evaluation of self‐rated and other‐rated OCB nomological networks showed that although self‐rated and other‐rated OCBs have similar patterns of relationships with common correlates, other‐rated OCB generally contributed negligible incremental variance to correlates and only contributed appreciable incremental variance to other‐rated behavioral variables (e.g., task performance and counterproductive work behavior). Implications and future research directions are discussed, particularly regarding the need to establish a nomological network for other‐rated OCB. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
327.
Decentralisation policies in least developed countries have emerged in response to failed centralised natural resource governance programmes because high-value natural resources are distributed unequally, with central governments often reaping more than local-level users. Current natural resource governance institutions have been created to remedy the problems that central governments formerly posed. Here, we argue that Uganda's forestry and fishery resources are biologically diverse and thus amenable to current decentralised management programmes, provided that there is compromise between market values and local cultural and subsistence values and uses. We observe, however, Uganda's current institutional arrangement favours the former over the latter and determine that successful natural resource decentralisation requires strengthening local-level natural resource institutions with increased fiscal flow, enforcement, monitoring and judicial powers. A strong and reliable partnership between local-level resource users and the central government is necessary for this to occur. 相似文献
328.
Meysam?Fazeli Mirmosadegh?JamaliEmail author Gregory?A.?Lawrence Brian?Seymour 《Environmental Fluid Mechanics》2016,16(2):401-412
The resonant interaction of surface and internal waves produces a nonlinear mechanism for energy transfer among wave components in oceans, lakes, and estuaries. In many field situations, the stratification may be well approximated by a two-layer fluid with a diffuse interface. The growth and damping rates of sub-harmonic interfacial waves generated by a surface wave through a three-wave resonant interaction are measured in the laboratory. These measurements are compared with theoretical predictions. A diffuse interface reduces the damping rate and increases the growth rate. The predicted growth rate provides excellent comparison with the laboratory measurements. The inclusion of the effects of a diffuse interface significantly improve the comparison. 相似文献
329.
330.
Trophic dynamics of U, Ni, Hg and other contaminants of potential concern on the Department of Energy’s Savannah River Site 总被引:1,自引:0,他引:1
Paul G. Edwards Karen F. Gaines A. Lawrence Bryan Jr. James M. Novak Susan A. Blas 《Environmental monitoring and assessment》2014,186(1):481-500
The Department of Energy’s Savannah River Site is a former nuclear weapon material production and current research facility located in South Carolina, USA. Wastewater discharges from a fuel and nuclear reactor target manufacturing facility released depleted and natural U, as well as other metals into the Tims Branch-Steed Pond water system. We investigated the current dynamics of this system for the purposes of environmental monitoring and assessment by examining metal concentrations, bioavailability, and trophic transfer of contaminants in seven ponds. Biofilm, detritus, and Anuran and Anisopteran larvae were collected and analyzed for stable isotopes (δ 15N, δ 13C) and contaminants of potential concern (COPC) with a focus on Ni, U, and Hg, to examine metal mobility. Highest levels of Ni and U were found in biofilms U (147 and 332 mg kg?1 DW, respectively), while highest Hg levels were found in tadpoles (1.1 mg kg?1 DW). We found intraspecific biomagnification of COPCs as expressed through stable isotope analysis. Biofilms were the best indicators for contamination and Anuran larvae with the digestive tract removed were the best indicators of the specific bioavailability of the focal metals. Monitoring data showed that baseline δ 15N values differed between ponds, but within a pond, values were stable throughout tadpole Gosner stage, strengthening the case to use this species for monitoring purposes. It is likely that there still is risk to ecosystem integrity as COPC metals are being assimilated into lower trophic organisms and even low levels of this mixture has shown to produce deleterious effects to some wildlife species. 相似文献