全文获取类型
收费全文 | 499篇 |
免费 | 1篇 |
国内免费 | 13篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 33篇 |
环保管理 | 22篇 |
综合类 | 228篇 |
基础理论 | 65篇 |
污染及防治 | 114篇 |
评价与监测 | 32篇 |
社会与环境 | 4篇 |
出版年
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2014年 | 12篇 |
2013年 | 22篇 |
2012年 | 18篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 28篇 |
2008年 | 17篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1969年 | 3篇 |
1967年 | 4篇 |
1966年 | 8篇 |
1965年 | 6篇 |
1964年 | 6篇 |
1963年 | 5篇 |
1962年 | 6篇 |
1961年 | 8篇 |
1960年 | 7篇 |
1959年 | 6篇 |
1958年 | 12篇 |
1957年 | 7篇 |
1956年 | 4篇 |
1955年 | 6篇 |
1954年 | 6篇 |
1953年 | 3篇 |
1952年 | 7篇 |
1951年 | 5篇 |
1950年 | 4篇 |
1943年 | 4篇 |
1940年 | 3篇 |
1938年 | 3篇 |
1928年 | 5篇 |
1927年 | 3篇 |
1926年 | 3篇 |
1923年 | 4篇 |
1922年 | 5篇 |
1921年 | 3篇 |
排序方式: 共有513条查询结果,搜索用时 15 毫秒
101.
102.
David R. Weise Heejung Jung Javier Palarea-Albaladejo David R. Cocker 《Journal of the Air & Waste Management Association (1995)》2020,70(8):834-845
ABSTRACT
Data describing the composition of smoke are inherently multivariate and always non-negative parts of a whole. The data are relative and the information is contained in the ratios between parts of the composition. A prior analysis of smoke emissions produced from the burning of manzanita wood mixed with low-density polyethylene plastic applied traditional statistical methods to the compositional data and found no effect. The current paper applies compositional data techniques to these smoke emissions to determine if the prior analysis was accurate. Analysis of variance of the isometric log-ratios showed that LDPE significantly affected the CO2 emission ratio for 8 of the 191 trace gases; this analysis showed none of the gases identified in the previous analysis were affected by LDPE. LDPE did not affect the CO2 emission ratios for the alkanes, alkenes, alkynes, aldehydes, cycloalkanes, cycloalkenes, diolefins, ketones, MAHs, and PAHs. Compositional data analysis should be used to analyze smoke emissions data. Burning contaminant-free LDPE should produce emissions like wood. 相似文献
103.
Min Hoan Moon Jeong Yeon Cho Yu Mi Lee Sung Il Jung Jae Hyug Yang Moon Young Kim Hyun-Mee Ryu Jin Hoon Chung Seong Ho Park 《黑龙江环境通报》2007,27(9):830-834
Objectives The aim of this study was to evaluate the role of nasal bone assessment in first-trimester screening for Down syndrome (DS) in the Korean population. Methods From July 2004 to March 2006, we prospectively evaluated the fetal nasal bones at 11–14 weeks' gestation in the Korean population. Results A successful evaluation was possible in 6490 of 6787 fetuses (95.6%). Absent, hypoechoic, and short nasal bones were seen in 4 (26.7%), 4 (26.7%), and 1 (6.7%) of 15 fetuses with DS, respectively, whereas in 5 (0.1%), 11 (0.2%), and 246 (3.8%) of 6456 normal fetuses. The incidence of absent and hypoechoic nasal bone showed significant differences between normal fetuses and fetuses with DS (P < 0.0005, both). Screening for DS using an absent or hypoechoic nasal bone resulted in a sensitivity of 53.3%, a specificity of 99.8%, a positive likelihood ratio of 215.2, and a negative likelihood ratio of 0.5. Conclusion Our study showed that nasal bone abnormality at 11–14 weeks of gestation had a high association with DS in the Korean population. This suggests that nasal bone assessment can be used to supplement the current first-trimester screening for DS in the Korean population. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
104.
In this paper we estimate a flexible form cost function of the aluminium industry in the USA and use our estimates to obtain derived demand curves for aluminium inputs such as electricity and bauxite. We then calculate the welfare gains arising from decreased energy use when the level of secondary recycling is increased. The process is repeated for several model specifications. All of our tests, however, yield similar results and indicate that substitution of scrap for only 5% of the bauxite presently used in US aluminium manufacturing would result in annual savings of close to a quarter of a billion dollars. 相似文献
105.
Anthropogenic impacts on natural nitrogen isotope variations in Pinus sylvestris stands in an industrially polluted area 总被引:2,自引:0,他引:2
Jung K Gebauer G Gehre M Hofmann D Weissflog L Schüürmann G 《Environmental pollution (Barking, Essex : 1987)》1997,97(1-2):175-181
Natural variations of the nitrogen isotopes 15N/14N (delta15N values) and the N concentrations of one-year-old needles from 7-12-year-old pine trees (Pinus sylvestris L.) were determined on 27 sites in the heavily polluted Leipzig-Halle region (former GDR). At three selected sites measurements were repeated over a period of 2 years. N concentrations and delta15N values in different needle age classes were compared at the three sites. The delta15N values of the N in the humus layer and the potential plant available N in the A(h) horizon of the local soil were determined. The 15N/14N isotope ratios (delta15N values) of one-year-old pine needles in the region of Leipzig-Halle were found to vary depending on their specific location by a factor of up to one order of magnitude (-9.6 per thousand to + 0.4 per thousand ). N concentrations in one-year-old pine needles varied between 0.71 and 1.38 mmol eq N g dw(-1). Pine stands with positive or slightly negative delta15N values and high N concentrations in one-year-old needles were concentrated around the cities of Leipzig and Halle and in the industrial areas. More negative delta15N values and lower N concentrations in one-year-old pine needles were found on sites at greater distances from the industrial agglomerations, mainly in the NE forested part. Site specific differences in the delta15N values of the N in the humus layer from three selected sites were similar to those found for the needles. No site specific differences, however, were found for the delta15N values of the water soluble nitrogen fraction from the mineral soil horizons of the same sites. 相似文献
106.
107.
108.
109.
110.
Friedrich -Wilhelm Bentrup 《Die Naturwissenschaften》1985,72(4):169-179