全文获取类型
收费全文 | 102633篇 |
免费 | 5505篇 |
国内免费 | 27178篇 |
专业分类
安全科学 | 4688篇 |
废物处理 | 3701篇 |
环保管理 | 14826篇 |
综合类 | 50154篇 |
基础理论 | 28513篇 |
环境理论 | 76篇 |
污染及防治 | 21458篇 |
评价与监测 | 7044篇 |
社会与环境 | 4091篇 |
灾害及防治 | 765篇 |
出版年
2022年 | 869篇 |
2021年 | 850篇 |
2020年 | 1259篇 |
2019年 | 2738篇 |
2018年 | 3207篇 |
2017年 | 3213篇 |
2016年 | 3993篇 |
2015年 | 4024篇 |
2014年 | 5450篇 |
2013年 | 12245篇 |
2012年 | 5145篇 |
2011年 | 4933篇 |
2010年 | 5508篇 |
2009年 | 5609篇 |
2008年 | 4059篇 |
2007年 | 3992篇 |
2006年 | 3778篇 |
2005年 | 3391篇 |
2004年 | 3531篇 |
2003年 | 3227篇 |
2002年 | 2701篇 |
2001年 | 3098篇 |
2000年 | 2660篇 |
1999年 | 2113篇 |
1998年 | 1848篇 |
1997年 | 1793篇 |
1996年 | 1921篇 |
1995年 | 1983篇 |
1994年 | 1770篇 |
1993年 | 1525篇 |
1992年 | 1584篇 |
1991年 | 1543篇 |
1990年 | 1488篇 |
1989年 | 1377篇 |
1988年 | 1197篇 |
1987年 | 1059篇 |
1986年 | 1059篇 |
1985年 | 1122篇 |
1984年 | 1209篇 |
1983年 | 1208篇 |
1982年 | 1222篇 |
1981年 | 1137篇 |
1980年 | 955篇 |
1979年 | 949篇 |
1978年 | 832篇 |
1977年 | 724篇 |
1976年 | 649篇 |
1974年 | 633篇 |
1973年 | 651篇 |
1972年 | 651篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
701.
An attempt was made to explain ambient air quality violations in the vicinity of industrial plants. Micrometeorology, diffusion calculaations, ambient readings, and plant engineering data are all taken into consideration to ascertain whether the plant is or is not the principal offender.Scrutiny of hi-vol filters using scanning electron microscopy for particle size analysis and particle chemical make-up as an assessment technique is also described.Case histories using the above analytical techniques are discussed.Presented at the 16th National Conference on Energy and the Environment, May 23, 1979 相似文献
702.
703.
Compilation of published and unpublished data shows acid precipitation to be more widespread in the Pacific coastal states than is generally recognized. Although information is scattered and discontinuous, precipitation is definitely acidic in the Los Angeles Basin and north-central california, and in the Puget Sound region in Washington. Acid rain occurrences have been observed in western and eastern Oregon, but data are inadequate for regional generalization. New stations currently being established in Washington and Oregon, largely in resposnse to the recently renewed activity of Mount St. Helens, will greatly facilitate assessment of precipitation acidity in the Northwest. 相似文献
704.
Biomass burning, in a broad sense, encompasses different burning practices, including open and confined burnings, and different types of vegetation. Emission factors of gaseous or particulate trace compounds are directly dependent both on the fuel type and the combustion process. Emission factors are generally calculated by stoichiometric considerations using the carbon mass balance method, applied either to combustion chamber experiments or to field experiments based on ground-level measurements or aircraft sampling in smoke plumes. There have been a number of experimental studies in the last 10 years to investigate wildfires in tropical, temperate, or boreal regions. This article presents an overview of measurement methods and experimental data on emission factors of reactive or radiatively active trace compounds, including trace gases and particles. It focuses on fires in tropical regions, that is, forest and savanna fires, agricultural burns, charcoal production, use of fuelwood, and charcoal combustion. 相似文献
705.
Bridget N. Bero Margrit C. von Braun Charles R. Knowles John E. Hammel 《Environmental monitoring and assessment》1995,36(2):123-138
The sampling of carpeted surfaces to test for lead contamination primarily focuses upon vacuum techniques. Vacuum sampling techniques, however, require time-consuming, expensive laboratory analysis of the dusts obtained and are unable to determine total lead load on the carpet. X-ray fluorescence (XRF) analysis is an on-site, inexpensive, non-destructive, quick technique for predicting metals levels in a variety of media, such as water, soil, filter paper and painted surfaces. A 1992 study of the feasibility of XRF to analyze for lead and soil loadings on carpeted surfaces indicated that XRF can detect lead at a low enough level to warrant further study. This paper expands this earlier study and developes lead and soil loading calibration curves for three different carpet types based upon XRF lead L-beta peak areas and XRF iron and barium K-alpha peak and background areas. Results indicate that variation in the data can be reduced through modifications of the XRF analysis technique, thus reducing the statistically determined detection level, and that carpet type does affect the calibration. Detection levels of approximately 70 mg/m2 for lead and 5 g/m2 for soil were obtained. Overall, good agreement was found between results of this study and the earlier one. XRF shows excellent potential for quantitative analysis of lead on carpeted surfaces. 相似文献
706.
唐山市空气中SO2与TSP污染状况分析 总被引:1,自引:0,他引:1
分析了唐山市从1988年至1992年大气中SO2和TSP的污染状况和变化规律,取得对该市环境管理的科学依据。 相似文献
707.
盐酸付玫瑰苯胺是三苯甲烷类染料,分子中存在的共轭体系使其具有以下特性:1.本身带色;2.随介质的pH变化产生显著的颜色效应,pH值越高,颜色越深,pH值越低,颜色越浅;3.对光和水洗的坚牢度较差;4.可发生重氮化反应;5.杂质使其颜色加深。 相似文献
708.
对绵阳市的环境放射源基本情况进行了分析,弄清了放射源的品种、数量。摸索出放射性核素及X射线装置在地域、行业和剂量方面的分布规律,揭示出环境放射性管理工作的重点。 相似文献
709.
Monte Carlo-assisted factor analysis has been applied to a data set of 20 trace-element concentrations in tree-bark samples obtained from 123 locations in The Netherlands, with the aim to investigate the suitability of bark as a biomonitor for air pollution. A Monte Carlo approach was used to give more insight to the uncertainties and significance levels of the factor analysis results. Notwith-standing a rather strong influence of soil material on the concentration levels, factor analysis enabled the identification of five significant pollution source types, all of which corresponded with source types found in an earlier biomonitoring study in The Netherlands using epiphytic lichens. A more detailed comparison with the lichen results showed a remarkable difference in lead concentrations between bark and lichen. It was concluded that bark can be successfully employed as a biomonitor for air pollution. The power of factor analysis to adequately determine the soil contribution may render extensive sample washing procedures superfluous. 相似文献
710.
V. M. Artyomov E. M. Artyomov Sh. D. Fridman 《Environmental monitoring and assessment》1994,29(3):221-228
The paper considers the methodology and results of experimental determination of dry deposition and ammonia uptake by isolated plant leaves. Analytical expressions are proposed which allow a transition from rates obtained in an isolated chamber to dry ammonia deposition by standing crops leaves. 相似文献