全文获取类型
收费全文 | 96481篇 |
免费 | 1278篇 |
国内免费 | 1317篇 |
专业分类
安全科学 | 3940篇 |
废物处理 | 3603篇 |
环保管理 | 14731篇 |
综合类 | 21758篇 |
基础理论 | 27203篇 |
环境理论 | 76篇 |
污染及防治 | 17324篇 |
评价与监测 | 5727篇 |
社会与环境 | 4067篇 |
灾害及防治 | 647篇 |
出版年
2022年 | 852篇 |
2021年 | 857篇 |
2020年 | 722篇 |
2019年 | 874篇 |
2018年 | 1227篇 |
2017年 | 1257篇 |
2016年 | 2258篇 |
2015年 | 1876篇 |
2014年 | 2621篇 |
2013年 | 9338篇 |
2012年 | 2509篇 |
2011年 | 3015篇 |
2010年 | 3451篇 |
2009年 | 3609篇 |
2008年 | 2559篇 |
2007年 | 2461篇 |
2006年 | 2701篇 |
2005年 | 2573篇 |
2004年 | 2862篇 |
2003年 | 2691篇 |
2002年 | 2265篇 |
2001年 | 2591篇 |
2000年 | 2187篇 |
1999年 | 1590篇 |
1998年 | 1392篇 |
1997年 | 1399篇 |
1996年 | 1512篇 |
1995年 | 1622篇 |
1994年 | 1497篇 |
1993年 | 1368篇 |
1992年 | 1344篇 |
1991年 | 1317篇 |
1990年 | 1283篇 |
1989年 | 1243篇 |
1988年 | 1082篇 |
1987年 | 1009篇 |
1986年 | 997篇 |
1985年 | 1088篇 |
1984年 | 1181篇 |
1983年 | 1177篇 |
1982年 | 1183篇 |
1981年 | 1113篇 |
1980年 | 953篇 |
1979年 | 952篇 |
1978年 | 831篇 |
1977年 | 725篇 |
1976年 | 656篇 |
1974年 | 645篇 |
1973年 | 669篇 |
1972年 | 669篇 |
排序方式: 共有10000条查询结果,搜索用时 647 毫秒
531.
Godderis L Vanderheyden W Van Geel J Moens G Masschelein R Veulemans H 《Journal of environmental monitoring : JEM》2005,7(12):1359-1363
To date the exposure, absorption and respiratory health effects of cast-house workers have not been described since most studies performed in the aluminium industry are focused on exposure and health effects of potroom personnel. In the present study, we assessed the external exposure and the absorbed dose of metals in personnel from the aluminium cast house. This was combined with an evaluation of respiratory complaints and the lung function of the personnel. 30 workers from an aluminium casting plant participated and 17 individuals of the packaging and distribution departments were selected as controls. The exposure was assessed by the quantification of total inhalable fume with metal fraction and by the determination of urinary aluminium, chromium, beryllium, manganese and lead concentration. Carbon monoxide (CO), carbon dioxide (CO2), aldehydes and polyaromatic hydrocarbons and man-made mineral fibres concentration were assessed as well. In order to evaluate their respiratory status each participant filled out a questionnaire and their lung function was tested by forced spirometry. Total inhalable fume exposure was maximum 4.37 mg m(-3). Exposure to the combustion gases, man-made mineral fibres and metal fume was well below the exposure limits. Beryllium could not be detected in the urine. The values of aluminium, manganese and lead in the urine were all under the respective reference value. One individual had a urinary chromium excretion above the ACGIH defined biological exposure index (BEI) of 30 microg g(-1) creatinine. There was no significant difference in any of the categories of the respiratory questionnaire and in the results of the spirometry between cast house personnel and referents (Chi-square, all p > 0.05). Exposure in cast houses seem to be acceptable under these conditions. However, peak exposure to fumes cannot be excluded and the potential risk of chromium and beryllium exposure due to the recycling of aluminium requires further attention. 相似文献
532.
A modular approach to Integrated Assessment modeling 总被引:1,自引:0,他引:1
In this paper, we present a new approach to model coupling that probably forms the methodological basis of a new generation of Integrated Assessment models. This approach respects the knowledge and expertise that is embodied in existing models and encourages their gradual evolution. Modularity is the guiding principle. Our approach is distinguished by the way modules are coupled which is based on an interplay of a job control module, a numerical coupling module, and a couple of stand-alone functional modules. The numerical coupling module - the core component - serves to treat the feedbacks between the functional modules. A first implemented example that couples an economic and a climate module by means of a two-phase meta-optimization is presented here. The algorithm and mathematical structure behind are discussed as well as important features such as convergence behavior and reliability. 相似文献
533.
534.
535.
536.
Summary As stated at the beginning of this paper conclusions reached thus far cannot be discussed in this paper. However, a great deal of information is available for examination.EPA displayed its ability to coordinate widely separated laboratories, both Federal and private, into a smooth working team in a very short period of time. A very comprehensive study plan was also developed and implemented quickly. EPA was fortunate to have already had GCA under contract when the emergency arose. In no small part the success of the field effort was due to the managerial and technical abilities of the GCA team.Within a period of 6 weeks a plan was developed, a prime contractor retained, subcontractors hired, and field activities begun. Within a period of 3 months in excess of 8600 field samples were collected and over 12,000 field and QC samples were analyzed. During this same period 2 major data systems were developed, debugged, and placed into operation.In short this EPA project was probably the most comprehensive multimedia field project ever attempted by EPA and certainly the data is being subjected to the most strenuous quality control measures ever imposed by this Agency. The entire program is presently under peer review and the results are being prepared for publication by EPA Headquarters.Note. Originally intended to be published as part of the special issue on Exposure Monitoring: An International Workshop (Las Vegas, Nevada, October 19–22, 1981). 相似文献
537.
538.
539.
The Variability of Estimates of Variance, and Its Effect on Power Analysis in Monitoring Design 总被引:1,自引:0,他引:1
Power analysis can be a valuable aid in the design of monitoringprograms. It requires an estimate of variance, which may come from a pilot study or an existing study in a similar habitat. For marine benthic infauna, natural variation in abundances canbe considerable, raising the question of reliability of varianceestimates. We used two existing monitoring programs to generatemultiple estimates of variance. These estimates were found to differ from nominated best estimates by 50% or more in 43% of cases, in turn leading to under or over-estimation of samplesize in the design of a notional monitoring program. The twostudies, from the same general area, using the same samplingmethods and spanning a similar time scale, gave estimatesvarying by more than an order of magnitude for 25% of taxa.We suggest that pilot studies for ecological monitoring programsof marine infauna should include at least two sampling times. 相似文献
540.
Lake V?nern, the largest lake in Sweden, has been seriously contaminated with mercury during the 20th century. In the 1970's and 80's the direct load, mainly from a chlor-alkali industry in the area, of mercury was drastically reduced as a response to new legislation, from three to five tons down to between five and ten kg yr(-1). Large amounts of the disposed pollutant have accumulated in the sediments. The question posed in this work is now, is the effect of the drastic load reduction after more than two decades visible in the sediments? The question is relevant as large areas still are blacklisted for fishing, but also as a follow-up of a major remedy action. The lake also serves as a freshwater reservoir for even Sweden's second largest city. This work synthesises and compares data of mercury in the sediments from three major field programs, in 1974, 1984 and 1998. The interest is focused on both spatial heterogeneity and temporal trends. In 1974, the surface concentrations are significantly higher than in subsequent surveys. Significant differences are also found between 1984 and 1998. Significant spatial differences within the lake are found for respective year. The most contaminated area is located in the north, close to the major point source (a former chlor-alkali industry). This is also the area with the largest improvement, as a direct response to the reduction in load. Further from the outlet, the recovery is more affected by burial and transport processes out into the deeper basins. 相似文献