全文获取类型
收费全文 | 803篇 |
免费 | 14篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 18篇 |
环保管理 | 238篇 |
综合类 | 82篇 |
基础理论 | 208篇 |
环境理论 | 1篇 |
污染及防治 | 177篇 |
评价与监测 | 26篇 |
社会与环境 | 30篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 36篇 |
2015年 | 23篇 |
2014年 | 31篇 |
2013年 | 76篇 |
2012年 | 45篇 |
2011年 | 34篇 |
2010年 | 19篇 |
2009年 | 37篇 |
2008年 | 33篇 |
2007年 | 35篇 |
2006年 | 25篇 |
2005年 | 23篇 |
2004年 | 33篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 17篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有821条查询结果,搜索用时 15 毫秒
701.
OBJECTIVE: The objective of this article is to explore relationship between older drivers and their passengers (co-pilots) and potential implications of in-vehicle navigation technology on their driving safety. METHODS: Semi-structured interviews were conducted with 44 healthy, community-dwelling older adults (aged 60-83) or 22 married couples. Males identified themselves as drivers and females identified themselves as passengers (i.e., co-pilot). RESULTS: Findings indicate that operating a motor vehicle in older adulthood is a shared activity between drivers and passengers. Older drivers and co-pilots reported their level of interaction depended on their familiarity with their route. Navigating unfamiliar areas, particularly large urban centers, was identified as the most challenging driving situation. Participants identified their level of collaboration would increase with the advent of in-vehicle navigation technology. Safety concerns related to the use of this technology, included distraction of both drivers and passengers. Differences amongst couples in their perceptions of using this technology were linked to their level of experience with using other forms of technology. CONCLUSIONS: Older drivers and passengers identified working closely together when operating a motor vehicle. Further investigation into the effects of in-vehicle navigation technology on the driving safety of older drivers and their co-pilots is warranted. 相似文献
702.
Elmira Kujundzic David A. Zander Largus T. Angenent David E. Henderson Shelly L. Miller 《Journal of the Air & Waste Management Association (1995)》2013,63(2):210-218
Abstract The purpose of this study was to assess the effectiveness of a new generation of high-volume, ceiling-mounted high-efficiency particulate air (HEPA)-ultraviolet (UV) air filters (HUVAFs) for their ability to remove or inactivate bacterial aerosol. In an environmentally controlled full-scale laboratory chamber (87 m3), and an indoor therapy pool building, the mitigation ability of air filters was assessed by comparing concentrations of total bacteria, culturable bacteria, and airborne endotoxin with and without the air filters operating under otherwise similar conditions. Controlled chamber tests with pure cultures of aerosolized Mycobacterium parafortuitum cells showed that the HUVAF unit tested provided an equivalent air-exchange rate of 11 hr?1. Using this equivalent air-exchange rate as a design basis, three HUVAFs were installed in an indoor therapy pool building for bioaerosol mitigation, and their effectiveness was studied over a 2-year period. The HUVAFs reduced concentrations of culturable bacteria by 69 and 80% during monitoring periods executed in respective years. The HUVAFs reduced concentrations of total bacteria by 12 and 76% during the same monitoring period, respectively. Airborne endotoxin concentrations were not affected by the HUVAF operation. 相似文献
703.
Amarpreet Chahal John Bissett Owen Rowland Myron L. Smith S. Shea Miller 《Journal of environmental science and health. Part. B》2013,48(12):945-954
The capacity of two soil fungi, Trichoderma koningii and Penicillium janthinellum, to oxidize n-C10:0 and n-C11:0 fatty acids to CO2 and store intracellular lipids during growth is unknown. This article reports for the first time the metabolism of decanoic acid (DA, C10:0), undecanoic acid (UDA, n-C11:0), a mixture of the acids (UDA+DA) and a mixture of UDA+ potato dextrose broth (PDB) by T. koningii and P. janthinellum and their mixed culture. A control PDB complex substrate was used as a substrate control treatment. The fungal cultures were assayed for their capacity to: (1) oxidize n-C10:0 and n-C11:0 fatty acids to CO2 and (2) store lipids intracellularly during growth. On all four fatty acid substrates, the mixed T. koningii and P. janthinellum culture produced more biomass and CO2 than the individual fungal cultures. Per 150 mL culture, the mixed species culture grown on UDA+PDB and on PDB alone produced the most biomass (7,567 mg and 11,425 mg, respectively). When grown in DA, the mixed species culture produced the least amount of biomass (6,400 mg), a quantity that was lower than those obtained in UDA (7,550 mg) or UDA+DA (7,270 mg). Amounts of CO2 produced ranged from 210 mg under DA to 618 mg under PDB, and these amounts were highly correlated with biomass (r2 = 0.99). Fluorescence microscopy of stained lipids in the mixed fungal cell cultures growing during the exponential phase demonstrated larger fungal cells and higher accumulation of lipids in membranes and storage bodies than those observed during the lag and stationary phases. T. koningii and P. janthinellum grown on n-C10:0 and n-C11:0 fatty acids produced lower amounts of biomass and CO2, but stored higher amounts of intracellular lipids, than when grown on PDB alone. 相似文献
704.
C.S. Eckley M. Gustin C.-J. Lin X. Li M.B. Miller 《Atmospheric environment (Oxford, England : 1994)》2010,44(2):194-203
Dynamic Flux Chambers (DFCs) are commonly applied for the measurement of non-point source mercury (Hg) emissions from a wide range of surfaces. A standard operating protocol and design for DFCs does not exist, and as a result there is a large diversity in methods described in the literature. Because natural and anthropogenic non-point sources are thought to contribute significantly to the atmosphere Hg pool, development of accurate fluxes during field campaigns is essential. The objective of this research was to determine how differences in chamber material, sample port placement, vertical cross sectional area/volume, and flushing flow rate influence the Hg flux from geologic materials. Hg fluxes measured with a Teflon chamber were higher than those obtained using a polycarbonate chamber, with differences related to light transmission and substrate type. Differences in sample port placement (side versus top) did not have an influence on Hg fluxes. When the same flushing flow rate was applied to two chambers of different volumes, higher fluxes were calculated for the chamber with the smaller volume. Conversely, when two chambers with different volumes were maintained at similar turnover times, the larger volume chamber yielded higher Hg fluxes. Overall, the flushing flow rate and associated chamber turnover time had the largest influence on Hg flux relative to the other parameters tested. Results from computational fluid dynamic (CFD) modeling inside a DFC confirm that the smaller diffusion resistance at higher flushing flows contributes to the higher measured flux. These results clearly illustrate that differences in chamber design and operation can significantly influence the resulting calculated Hg flux, and thus impact the comparability of results obtained using DFC designs and/or operating parameters. A protocol for determining a flushing flow rate that results in fluxes less affected by chamber operating conditions and design is proposed. Application of this protocol would provide a framework for comparison of data from different studies. 相似文献
705.
706.
707.
Abstract Contaminated soils can be a source for crop plants of such elements like As, Cd, Cr, Cu, Ni, Pb, and Zn. The excessive transfer of As, Cu, Ni, and Zn to the food chain is controlled by a “soil‐plant barrier”; however, for some elements, including Cd, the soil‐plant barrier fails. The level of Cd ingested by average person in USA is about 12 μg/day, which is relatively low comparing to Risk Reference Dose (70 μg Cd/day) established by USEPA. Food of plant origin is a main source of Cd intake by modern society. Fish and shellfish may be a dominant dietary sources of Hg for some human populations. About half of human Pb intake is through food, of which more than half originates from plants. Dietary intake of Cd and Pb may be increased by application of sludges on cropland with already high levels of these metals. Soils amended with sludges in the USA will be permitted (by USEPA‐503 regulations) to accumulate Cr, Cd, Cu, Pb, Hg, Ni, and Se, and Zn to levels from 10 to 100 times the present baseline concentrations. These levels are very permissive by international standards. Because of the limited supply of toxicity data obtained from metals applied in sewage sludge, predictions as to the new regulations will protect crop plants from metal toxicities, and food chain from contamination, are difficult to make. 相似文献
708.
Behavioral type–environment correlations occur when specific behavioral types of individuals are more common in certain environments. Behavioral type–environment correlations can be generated by several different mechanisms that are probably very common such as niche construction and phenotypic plasticity. Moreover, behavioral type–environment correlations have important ecological and evolutionary implications. However, few studies have examined behavioral type–environment correlations in natural populations. In this study, we asked whether some behavioral types of three-spined stickleback were more likely to occur in certain social environments (alone or in a shoal with other stickleback) or in certain microhabitats in a river (in the open or under cover). We found that individuals that were in shoals with other stickleback at the time of collection from the field emerged from a refuge more quickly compared to individuals that were found alone. In addition, fish that were alone in an open microhabitat explored more of a pool compared to fish that were alone in cover, but this difference did not occur among fish that were in shoals at the time of collection. Subsequent analyses of gut contents suggested that differences in microhabitat use were consistent over time. Our study provides some of the first evidence for behavioral type–environment correlations in a natural population of non-human animals. 相似文献
709.
710.
Carrie Miller Kelly G. Gordon Robert J. Kieber Joan D. Willey Pamela J. Seaton 《Atmospheric environment (Oxford, England : 1994)》2009,43(15):2497-2502
Proton nuclear magnetic resonance (1H-NMR), UV absorbance and excitation-emission matrix (EEM) fluorescence spectroscopy were used to define the chemical characteristics of chromophoric dissolved organic matter (CDOM) in whole and C18 extracted rainwater. The average total recovery of fluorescence determined from the sum of extract and filtrate fractions relative to the whole was 86% suggesting that 14% of fluorescent CDOM in rainwater is comprised of very hydrophobic material that cannot be eluted from the column. Half the fluorescence of rainwater was recovered in the filtrate fraction which is important because it suggests that 50% of the chromophoric material present in precipitation is relatively hydrophilic. The average spectral slope coefficient was smaller in extracted samples (16.3 ± 9.0 μm?1) relative to whole samples (18.9 ± 2.8 μm?1) suggesting that the extracted material contains larger molecular weight material. Approximately one-third of the total dissolved organic carbon (DOC) in rainwater exists in the extract fraction suggesting that a large percentage of the uncharacterized DOC in rainwater can be accounted for by these hydrophobic macromolecular species. The fluorescence of extracted samples is strongly correlated with total NMR integration and is most sensitive to aromatic protons suggesting that molecules in this region are the most important in controlling the optical properties of rainwater. The lower removal efficiency of CDOM in rainwater relative to surface waters or the water-soluble fraction of aerosols during solid phase extraction (SPE) suggests that rainwater contains significantly more hydrophilic chromophoric compounds which are compositionally different than found in these other aquatic matrices. 相似文献