全文获取类型
收费全文 | 680篇 |
免费 | 45篇 |
国内免费 | 91篇 |
专业分类
安全科学 | 66篇 |
废物处理 | 10篇 |
环保管理 | 249篇 |
综合类 | 214篇 |
基础理论 | 104篇 |
污染及防治 | 40篇 |
评价与监测 | 59篇 |
社会与环境 | 43篇 |
灾害及防治 | 31篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 40篇 |
2019年 | 23篇 |
2018年 | 19篇 |
2017年 | 24篇 |
2016年 | 27篇 |
2015年 | 16篇 |
2014年 | 30篇 |
2013年 | 38篇 |
2012年 | 29篇 |
2011年 | 46篇 |
2010年 | 29篇 |
2009年 | 45篇 |
2008年 | 74篇 |
2007年 | 55篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有816条查询结果,搜索用时 281 毫秒
631.
We monitored nest boxes during 1997–1999 at Acadia National Park, Mt. Desert Island, ME and at an old-field site in Orono,
ME to determine mercury (Hg) uptake in tree swallow (Tachycineta bicolor) eggs, tissues, and food boluses. Also, in 1998–1999 we monitored nest boxes at Grove Pond and Plow Shop Pond at a U.S. Environmental
Protection Agency Superfund site in Ayer, MA. We recorded breeding success at all locations. On average among locations, total
mercury (THg) biomagnified 2 to 4-fold from food to eggs and 9 to 18-fold from food to feathers. These are minimum values
because the proportion of transferable methyl mercury (MeHg) of the THg in insects varies (i.e., 35%–95% of THg) in food boluses.
THg was highest in food boluses at Aunt Betty Pond at Acadia, whereas THg in eggs was highest at the Superfund site. A few
eggs from nests at each of these locations exceeded the threshold (i.e., 800–1,000 ng/g, wet wt.) of embryotoxicity established
for Hg. Hatching success was 88.9% to 100% among locations, but five eggs failed to hatch from 4 of the 11 clutches in which
an egg exceeded this threshold. MeHg in feathers was highest in tree swallows at Aunt Betty Pond and the concentration of
THg in bodies was related to the concentration in feathers. Transfer of an average of 80%–92% of the Hg in bodies to feathers
may have enhanced nestling survival. Residues of Hg in tissues of tree swallows in the Northeast seem higher than those of
the Midwest. 相似文献
632.
Nelson SJ Johnson KB Kahl JS Haines TA Fernandez IJ 《Environmental monitoring and assessment》2007,126(1-3):69-80
Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia
National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac
Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition
would be higher at Hadlock Brook (the reference watershed, 10.2 μg/m2/year) than Cadillac (9.4 μg/m2/year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and
DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along
with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating
vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 μg/m2/year) than from Hadlock Brook watershed (1.3 μg/m2/year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that
∼50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower
soil pools, and greater ecosystem retention for both Hg and DIN. 相似文献
633.
Peckenham JM Kahl JS Nelson SJ Johnson KB Haines TA 《Environmental monitoring and assessment》2007,126(1-3):97-104
Fall and spring streamwater samples were analyzed for total mercury (Hg) and major ions from 47 locations on Mount Desert
Island in Maine. Samples were collected in zones that were burned in a major wildfire in 1947 and in zones that were not burned.
We hypothesized that Hg concentrations in streamwater would be higher from unburned sites than burned watersheds, because
fire would volatilize stored Hg. The Hg concentrations, based on burn history, were not statistically distinct. However, significant
statistical associations were noted between Hg and the amount of wetlands in the drainage systems and with streamwater dissolved
organic carbon (DOC). An unexpected result was that wetlands mobilized more Hg by generating more DOC in total, but upland DOC was more efficient at transporting Hg because it transports more Hg per unit DOC. Mercury concentrations were higher in samples collected at lower elevations. Mercury was positively correlated with relative
discharge, although this effect was not distinguished from the DOC association. In this research, sample site elevation and
the presence of upstream wetlands and their associated DOC affected Hg concentrations more strongly than burn history. 相似文献
634.
Bank MS Burgess JR Evers DC Loftin CS 《Environmental monitoring and assessment》2007,126(1-3):105-115
We reviewed literature reporting both total and methylmercury from biota from Acadia National Park, Maine, USA. Our review
of existing data indicates that 1) mercury contamination is widespread throughout the Park’s various aquatic ecosystems; 2)
mercury pollution likely represents a moderate to high risk to biota inhabiting the Park; and 3) biota at all trophic levels
possess elevated concentrations of both total and methylmercury. Watershed fire history and the resulting post-fire forest
succession patterns are an important landscape attribute governing mercury cycling at Acadia National Park. Therefore, park
service personnel should consider these factors when planning and implementing Hg biomonitoring efforts. Additional baseline
funding from the National Park Service for Hg research and biomonitoring will likely be required in order to further evaluate
the spatial and temporal patterns of mercury contamination in the park’s biota.
An erratum to this article can be found at 相似文献
635.
Johnson KB Haines TA Kahl JS Norton SA Amirbahman A Sheehan KD 《Environmental monitoring and assessment》2007,126(1-3):55-67
Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to
16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac
Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested
watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental
movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other
vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was
not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed
(burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were
weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was
not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 μg/m2/year in Cadillac Brook watershed and 10.2 μg/m2/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 μg/m2/year in Cadillac Brook watershed and 0.10 μg/m2/year in Hadlock Brook watershed. 相似文献
636.
ISO14000系列标准以生命周期评价理论和方法标准为基础,推出了环境管理体系与环境标志等国际环境管理标准,反映出现代环境意识引导下的双绿色发展模式,并成为可持续发展道路的重要组成部分。 相似文献
637.
638.
金属铸造企业,特别是铸铁生产企业是机械加工行业的重要组成部分之一,本文以中国北车集团沈阳机车车辆有限责任公司铸造系统技术改造为例,针对该厂对铸造系统的改造前后所用工艺及设备的不同,剖析在进行该类项目环评过程中的重点及该类项目的清洁生产工艺情况。 相似文献
639.
640.
成都未来气候变化趋势的R/S分析 总被引:8,自引:0,他引:8
运用R/S分析法,对1951~2002年成都的平均值气温、极端气温值及降水累积值进行了计算分析。研究表明,成都未来气候变化趋势与过去50年来的变化趋势有着很好的自相似性。今后成都将继续变暖。依平均气候倾向率,未来10年,年平均气温将升高0.25°C,年平均最低气温将升高0.14 °C,年平均最高气温将升高0.04 °C,年极端最低气温将升高0.54 °C,年极端最高气温将升高0.13 °C。其中,年平均气温、年平均最低气温和年平均最高气温升高趋势的持续性强度很强。成都未来降水量将继续减少。未来10年的年降水量将减少45.2 mm,并且这种减少趋势具有很强的持续性强度。 相似文献