全文获取类型
收费全文 | 977篇 |
免费 | 32篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 54篇 |
废物处理 | 43篇 |
环保管理 | 259篇 |
综合类 | 92篇 |
基础理论 | 259篇 |
环境理论 | 2篇 |
污染及防治 | 199篇 |
评价与监测 | 67篇 |
社会与环境 | 34篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 22篇 |
2016年 | 28篇 |
2015年 | 30篇 |
2014年 | 26篇 |
2013年 | 60篇 |
2012年 | 59篇 |
2011年 | 59篇 |
2010年 | 41篇 |
2009年 | 61篇 |
2008年 | 69篇 |
2007年 | 60篇 |
2006年 | 57篇 |
2005年 | 34篇 |
2004年 | 42篇 |
2003年 | 39篇 |
2002年 | 35篇 |
2001年 | 9篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 14篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1961年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有1017条查询结果,搜索用时 750 毫秒
881.
Russell J. Anderson Brian P. Bledsoe W. Cully Hession 《Journal of the American Water Resources Association》2004,40(5):1159-1172
ABSTRACT: An extensive group of datasets was analyzed to examine factors affecting widths of streams and rivers. Results indicate that vegetative controls on channel size are scale dependent. In channels with watersheds greater than 10 to 100 km2, widths are narrower in channels with thick woody bank vegetation than in grass lined or nonforested banks. The converse is true in smaller streams apparently due to interactions between woody debris, shading, understory vegetation, rooting characteristics, and channel size. A tree based statistical method (regression tree) is introduced and tested as a tool for identifying thresholds of response and interpreting interactions between variables. The implications of scale dependent controls on channel width are discussed in the context of stable channel design methods and development of regional hydraulic geometry curves. 相似文献
882.
883.
Neckel Alcindo Korcelski Cleiton Silva Luis F. O. Kujawa Henrique Aniceto Bodah Brian William Figueiredo Adriano Marcos Rodrigues Maculan Larcio Stolfo Gonalves Affonso Celso Bodah Eliane Thaines Moro Leila Dal 《Environment, Development and Sustainability》2022,24(9):10728-10751
Environment, Development and Sustainability - The increasing mortality of COVID-19 can aggravate soil contamination by metals, harmful to the health of the population, requiring new projects for... 相似文献
884.
885.
Use of 210Pb and 137Cs to simultaneously constrain ages and sources of post-dam sediments in the Cordeaux reservoir, Sydney, Australia 总被引:2,自引:0,他引:2
Simms AD Woodroffe C Jones BG Heijnis H Mann RA Harrison J 《Journal of environmental radioactivity》2008,99(7):1111-1120
Environmental radionuclides can be employed as tracers of sediment movement and delivery to water bodies such as lakes and reservoirs. The chronologies of sediments that have accumulated in the Cordeaux reservoir in Sydney, Australia, were determined by the rate of change of (210)Pb(ex) with depth and indicate slow accretion in the reservoir. The ratio of enrichment of radionuclides in sediment cores to (210)Pb(ex) and (137)Cs concentrations in a reference soil sample within the Cordeaux catchment indicates that the dominant source of sediment in the Cordeaux reservoir is surface erosion (detachment and removal of sediment at depths less than 30 cm). However, in the Kembla Creek arm of the reservoir a mixture of sources was detected and includes sheet and rill erosion together with sub-soil contributions. Implications for the utility of these radionuclide sedimentation assessments, especially where samples are limited, are that well-constrained chronologies and sources of soil erosion are facilitated. 相似文献
886.
This paper evaluates the use of a nickel nanoparticle (NiNP) interlayer for making hermetic joints in 316L stainless steel substrates via diffusion brazing. Different NiNP inks were prepared using commercial nanopowder (~9 nm) and in-house synthesized nanoparticles. Syringe pump deposition of ~9 nm NiNP ink and diffusion brazing at 900 °C for 30 min under 2 MPa resulted in a hermetic joint up to the tested pressure of 70 psi. In-house synthesis of NiNPs was carried out in ethylene glycol by the reduction of NiCl2·6H2O in the presence of hydrazine (N2H4) as a reducing agent. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) results confirm the presence of pure fcc-Ni with an average particle size of 5.4 ± 0.9 nm. An as-synthesized suspension of NiNPs was patterned onto 316L stainless steel laminae via automated dispensing to a thickness of ~3 μm and bonded at 800 °C for 30 min at a pressure of 2 MPa. The diffusion-brazed test article was also found to be hermetic up to 70 psi. An examination of the bond line using scanning electron microscopy (SEM) showed good uniformity and continuity. 相似文献
887.
Andrea Ludwig Marty Matlock Brian Haggard Indrajeet Chaubey 《Journal of the American Water Resources Association》2012,48(5):896-908
Ludwig, Andrea, Marty Matlock, Brian Haggard, and Indrajeet Chaubey, 2012. Periphyton Nutrient Limitation and Maximum Potential Productivity in the Beaver Lake Basin, United States. Journal of the American Water Resources Association (JAWRA) 48(5): 896‐908. DOI: 10.1111/j.1752‐1688.2012.00657.x Abstract: The objectives of this study were to measure periphytic growth responses to enrichment with nitrogen (N), phosphorus (P), and simultaneous N and P using in situ bioassays in streams draining Beaver Reservoir Basin, Northwest Arkansas; compare periphytic growth responses measured with in situ bioassays with a range of land use and point sources; and test the lotic ecosystem trophic status index (LETSI) as a simplifying metric to compare effects of nonpoint‐source pollutant‐limiting variables of N, P, and sediment across the basin. P limitation was observed at sites across a transect of stream orders throughout the basin; however, at the two sites with highest ambient nitrogen concentrations, limitation was often coupled with nitrogen limitation. Nutrients were at nonlimiting levels at both of two sites below wastewater treatment plants in all seasonal deployments. A Michaelis‐Menten growth equation described LETSI as a function of ambient PO4‐P concentrations (p < 0.05); the midpoint (LETSI of 0.50) corresponded with a PO4‐P concentration of approximately 3 μg/l. Change‐point analysis indicated a threshold point at LETSI of 0.80 and 15 μg/l PO4‐P. These low values show that the periphytic community has a high affinity for available P, and that the watershed as a whole is sensitive to available nutrient inputs. 相似文献
888.
Branislav Igic David R. Greenwood David J. Palmer Phillip Cassey Brian J. Gill Tomas Grim Patricia L. R. Brennan Suzanne M. Bassett Phil F. Battley Mark E. Hauber 《Chemoecology》2010,20(1):43-48
The known chemical basis of diverse avian eggshell coloration is generated by the same two classes of tetrapyrrole pigments
in most living birds. We aimed to extend the evolutionary scope of these patterns by detecting pigments from extinct birds’
eggs. In our samples biliverdin was successfully extracted from subfossil shell fragments of the blue-green egg-laying upland
moa Megalapteryx didinus, while protoporphyrin was extracted from the beige eggs of two other extinct moa species. Our data on pigment detection from
eggshells of other extant paleognath birds, together with published information on other modern lineages, confirm tetrapyrroles
as ubiquitous and conserved pigments contributing to diverse eggshell colours throughout avian evolution. 相似文献
889.
890.
Robert J. Hawley Brian P. Bledsoe Eric D. Stein Brian E. Haines 《Journal of the American Water Resources Association》2012,48(4):722-744
Hawley, Robert J., Brian P. Bledsoe, Eric D. Stein, and Brian E. Haines, 2012. Channel Evolution Model of Semiarid Stream Response to Urban‐Induced Hydromodification. Journal of the American Water Resources Association (JAWRA) 48(4): 722‐744. DOI: 10.1111/j.1752‐1688.2012.00645.x Abstract: We present a novel channel evolution model (CEM) that qualitatively describes morphologic responses of semiarid channels to altered hydrologic and sediment regimes associated with urbanization (hydromodification). The CEM is based on southern California data from 83 detailed channel surveys, hundreds of synoptic surveys, and historical analyses of aerial photographs along 14 reaches. Channel evolution sometimes follows the well‐known sequence described by Schumm et al. (Incised Channels: Morphology, Dynamics, and Control, Water Resources Publications, Littleton, Colorado, 1984) for incising, single‐thread channels; however, departures from this sequence are common and include transitions of single thread to braided evolutionary endpoints, as opposed to a return to quasi‐equilibrium single‐thread planform. Thresholds and risk factors associated with observed channel response are also presented. In particular, distance to grade control and network position emerged as key controls on channel response trajectory. The CEM and quantitative extensions provide managers with a framework for understanding channel responses and rehabilitation alternatives, and may be transferable to other semiarid settings. It also offers insights regarding channel susceptibility to hydromodification, highlights key boundary conditions for high‐risk channels, and underscores critical knowledge gaps in predicting the complex, discontinuous response trajectories that are highly prevalent in urbanized watersheds. 相似文献