全文获取类型
收费全文 | 1103篇 |
免费 | 42篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 56篇 |
废物处理 | 63篇 |
环保管理 | 299篇 |
综合类 | 99篇 |
基础理论 | 296篇 |
环境理论 | 4篇 |
污染及防治 | 219篇 |
评价与监测 | 76篇 |
社会与环境 | 48篇 |
灾害及防治 | 9篇 |
出版年
2023年 | 14篇 |
2022年 | 14篇 |
2021年 | 17篇 |
2020年 | 24篇 |
2019年 | 16篇 |
2018年 | 43篇 |
2017年 | 44篇 |
2016年 | 64篇 |
2015年 | 46篇 |
2014年 | 44篇 |
2013年 | 85篇 |
2012年 | 64篇 |
2011年 | 88篇 |
2010年 | 52篇 |
2009年 | 57篇 |
2008年 | 58篇 |
2007年 | 63篇 |
2006年 | 49篇 |
2005年 | 31篇 |
2004年 | 44篇 |
2003年 | 34篇 |
2002年 | 30篇 |
2001年 | 14篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有1169条查询结果,搜索用时 31 毫秒
71.
Designing and Implementing a Network for Sensing Water Quality and Hydrology across Mountain to Urban Transitions 下载免费PDF全文
Amber Spackman Jones Zachary T. Aanderud Jeffery S. Horsburgh David P. Eiriksson Dylan Dastrup Christopher Cox Scott B. Jones David R. Bowling Jonathan Carlisle Gregory T. Carling Michelle A. Baker 《Journal of the American Water Resources Association》2017,53(5):1095-1120
Water resources are increasingly impacted by growing human populations, land use, and climate changes, and complex interactions among biophysical processes. In an effort to better understand these factors in semiarid northern Utah, United States, we created a real‐time observatory consisting of sensors deployed at aquatic and terrestrial stations to monitor water quality, water inputs, and outputs along mountain to urban gradients. The Gradients Along Mountain to Urban Transitions (GAMUT) monitoring network spans three watersheds with similar climates and streams fed by mountain winter‐derived precipitation, but that differ in urbanization level, land use, and biophysical characteristics. The aquatic monitoring stations in the GAMUT network include sensors to measure chemical (dissolved oxygen, specific conductance, pH, nitrate, and dissolved organic matter), physical (stage, temperature, and turbidity), and biological components (chlorophyll‐a and phycocyanin). We present the logistics of designing, implementing, and maintaining the network; quality assurance and control of numerous, large datasets; and data acquisition, dissemination, and visualization. Data from GAMUT reveal spatial differences in water quality due to urbanization and built infrastructure; capture rapid temporal changes in water quality due to anthropogenic activity; and identify changes in biological structure, each of which are demonstrated via case study datasets. 相似文献
72.
Elsa Aristodemou Tom Bentham Christopher Pain Roy Colvile Alan Robins Helen ApSimon 《Atmospheric environment (Oxford, England : 1994)》2009,43(39):6238-6253
In this paper we address two important aspects of micro-scale urban airflow model evaluation: (a) the identification of key flow features as dictated by the physics of the problem and as captured by the simulations, and (b) the comparison of important model output parameters (mean flows and fluctuations) with experimental data. A series of mesh-adaptive large eddy simulations (LES) was carried out for the study of air flows within two intersecting street canyons with varying building configurations. The novelty of the approach lies in the combination of LES with mesh adaptivity, which allows a variable-filter length and the implementation of an anisotropic eddy-viscosity model. Both coarse and fine-mesh simulations were carried out, using single and parallel-processor systems respectively. The simulations showed clearly that the expected flow patterns such as the street canyon recirculation and the street-mouth vortices, as well as the exchange of air flow at the street intersections, can readily be captured by the mesh-adaptive LES.In addition, the detailed comparisons of mean flows and fluctuations of the resolved velocity field with the measured data showed that the simulation results agreed well with the patterns and trends of the wind tunnel measurements. In most cases the finer-mesh simulations improved considerably the accuracy of the mean flows, especially for the symmetrical configuration. The improvement in the predicted fluctuations was less obvious, with several detector locations underpredicting the measured values, although the overall comparison was also satisfactory. The typical errors for the mean flows for all three building configurations were less than 30%, whilst for the velocity fluctuations less that 40%. Both the simulated means flows and turbulence levels were generally more accurate in the streets parallel to the wind (streamwise direction) than in the streets normal to the wind. 相似文献
73.
Benjamin M. Jones Christopher D. Arp Kenneth M. Hinkel Richard A. Beck Joel A. Schmutz Barry Winston 《Environmental management》2009,43(6):1071-1084
Lakes are dominant landforms in the National Petroleum Reserve Alaska (NPRA) as well as important social and ecological resources.
Of recent importance is the management of these freshwater ecosystems because lakes deeper than maximum ice thickness provide
an important and often sole source of liquid water for aquatic biota, villages, and industry during winter. To better understand
seasonal and annual hydrodynamics in the context of lake morphometry, we analyzed lakes in two adjacent areas where winter
water use is expected to increase in the near future because of industrial expansion. Landsat Thematic Mapper and Enhanced
Thematic Mapper Plus imagery acquired between 1985 and 2007 were analyzed and compared with climate data to understand interannual
variability. Measured changes in lake area extent varied by 0.6% and were significantly correlated to total precipitation
in the preceding 12 months (p < 0.05). Using this relation, the modeled lake area extent from 1985 to 2007 showed no long-term trends. In addition, high-resolution
aerial photography, bathymetric surveys, water-level monitoring, and lake-ice thickness measurements and growth models were
used to better understand seasonal hydrodynamics, surface area-to-volume relations, winter water availability, and more permanent
changes related to geomorphic change. Together, these results describe how lakes vary seasonally and annually in two critical
areas of the NPRA and provide simple models to help better predict variation in lake-water supply. Our findings suggest that
both overestimation and underestimation of actual available winter water volume may occur regularly, and this understanding
may help better inform management strategies as future resource use expands in the NPRA. 相似文献
74.
A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species 总被引:1,自引:0,他引:1
John Pierce Wise Sr. Roger Payne Sandra S. Wise Carolyne LaCerte James Wise Christy Gianios Jr. W. Douglas Thompson Christopher Perkins Tongzhang Zheng Cairong Zhu Lucille Benedict Iain Kerr 《Chemosphere》2009,75(11):1461-1467
Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 μg Cr g tissue−1 with a global mean of 8.8 ± 0.9 μg g−1. Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean = 44.3 ± 14.4) and the Seychelles in the Indian Ocean (mean = 19.5 ± 5.4 μg g−1). The lowest mean levels were found in whales near the Canary Islands (mean = 3.7 ± 0.8 μg g−1) and off of the coast of Sri Lanka (mean = 3.3 ± 0.4 μg g−1). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed. 相似文献
75.
76.
Patrick L. Witmer Paul M. Stewart Christopher K. Metcalf 《Journal of the American Water Resources Association》2009,45(3):734-747
Abstract: Unpaved road‐stream crossings increase sediment yields in streams and alter channel morphology and stability. Before restoration and sedimentation reduction strategies can be implemented, a priority listing of unpaved road‐stream crossings must be created. The objectives of this study were to develop a sedimentation risk index (SRI) for unpaved road‐stream crossings and to prioritize 125 sites in the Choctawhatchee watershed (southeastern Alabama) using this model. Field surveys involved qualitative and quantitative observations of 73 metrics related to waterway conditions, crossing structures, road approaches, and roadside soil erosion. The road‐stream crossing risk analyses involved elimination of candidate metrics based on redundancy, skewness, lack of data, professional judgment, lack of nonzero values, unbalanced box plots, and limited ranges of values. A final selection of 12 metrics formed the SRI and weighed factors involving soil erodibility, road sedimentation abatement features, and stream morphology alteration. The SRI was organized into narrative categories (excellent, good, fair, poor, and very poor) based on the distribution of scores. No excellent sites (scores ≥55) were found in this study, 17 (20.7%) were good (low sedimentation risk), 37 (45.1%) were fair (moderate sedimentation risk), 26 (31.7%) were poor (high sedimentation risk), and two (2.5%) were very poor (high sedimentation risk). There was no significant difference in SRI scores among crossing structure type (round culverts, box culverts, and bridges) (H = 4.31, df = 2, p = 0.058). A future study of the Choctawhatchee watershed involving the same study sites could assess the success of restoration plans and activities based on site score improvement or decline. 相似文献
77.
Suzanne J.T. Hangx Christopher J. Spiers 《International Journal of Greenhouse Gas Control》2009,3(6):757-767
Qualitative proposals to control atmospheric CO2 concentrations by spreading crushed olivine rock along the Earth's coastlines, thereby accelerating weathering reactions, are presently attracting considerable attention. This paper provides a critical evaluation of the concept, demonstrating quantitatively whether or not it can contribute significantly to CO2 sequestration. The feasibility of the concept depends on the rate of olivine dissolution, the sequestration capacity of the dominant reaction, and its CO2 footprint. Kinetics calculations show that offsetting 30% of worldwide 1990 CO2 emissions by beach weathering means distributing of 5.0 Gt of olivine per year. For mean seawater temperatures of 15–25 °C, olivine sand (300 μm grain size) takes 700–2100 years to reach the necessary steady state sequestration rate and is therefore of little practical value. To obtain useful, steady state CO2 uptake rates within 15–20 years requires grain sizes <10 μm. However, the preparation and movement of the required material poses major economic, infrastructural and public health questions. We conclude that coastal spreading of olivine is not a viable method of CO2 sequestration on the scale needed. The method certainly cannot replace CCS technologies as a means of controlling atmospheric CO2 concentrations. 相似文献
78.
Businesses offering to make you or your company carbon neutral are proliferating on the Internet. The term carbon neutral is being defined by common usage. There are no standard ways of measuring your carbon emissions and so no standards for becoming carbon neutral. This paper examines eleven websites offering carbon neutrality. It compares online calculators, their results and the costs of offsetting calculated on the strength of those results. It traces two offset projects: one in Kenya, offering voluntary offsets and run by a not-for-profit organisation; one in India striving for UN Clean Development Mechanism status. The projects are traced from the online carbon offset retailer to the actual project on the ground in order to compare the online rhetoric with the time consuming and difficult work of developing community based projects in Third World countries. The paper offers a definition of carbon neutral based on the ways in which the term is being used. It also uncovers a range of issues for further discussion. 相似文献
79.
Turnover potentially leads to a new individual being selected into a work team. This study investigated the safety-specific trust which team members place in their organisation’s selection and induction processes, and related this to the perceived risk from new employees. The research was conducted with teams working in forest harvesting, an occupation which has high-turnover, high risk and a high accident rate. Results indicate that trust in induction processes was negatively correlated with perceived risk from a new employee. Team members also engaged in a number of safety ensuring behaviours when a new individual joined the team, and these were related to the level of perceived risk, and how much they cared about their team members’ safety. It is argued that trust in the safety-specific characteristics of an organisation’s selection and induction process may have negative consequences for safety. 相似文献
80.
de Grenade Rafael Rudow Joshua Taboada Hermoza Rossi Adauto Aguirre Maria Elena Scott Christopher A. Willems Bram Schultz Jennifer L. Varady Robert G. 《Regional Environmental Change》2017,17(3):789-802
Regional Environmental Change - Mountainous areas with extreme elevation gradients and corresponding ranges of biophysical and socioeconomic conditions are highly vulnerable to global change. We... 相似文献