全文获取类型
收费全文 | 8226篇 |
免费 | 129篇 |
国内免费 | 76篇 |
专业分类
安全科学 | 291篇 |
废物处理 | 320篇 |
环保管理 | 966篇 |
综合类 | 2415篇 |
基础理论 | 1743篇 |
环境理论 | 10篇 |
污染及防治 | 1778篇 |
评价与监测 | 548篇 |
社会与环境 | 305篇 |
灾害及防治 | 55篇 |
出版年
2023年 | 55篇 |
2022年 | 91篇 |
2021年 | 85篇 |
2020年 | 85篇 |
2019年 | 98篇 |
2018年 | 149篇 |
2017年 | 177篇 |
2016年 | 214篇 |
2015年 | 170篇 |
2014年 | 227篇 |
2013年 | 536篇 |
2012年 | 305篇 |
2011年 | 326篇 |
2010年 | 293篇 |
2009年 | 324篇 |
2008年 | 352篇 |
2007年 | 380篇 |
2006年 | 307篇 |
2005年 | 275篇 |
2004年 | 244篇 |
2003年 | 249篇 |
2002年 | 217篇 |
2001年 | 179篇 |
2000年 | 152篇 |
1999年 | 147篇 |
1998年 | 105篇 |
1997年 | 112篇 |
1996年 | 83篇 |
1995年 | 106篇 |
1994年 | 105篇 |
1993年 | 75篇 |
1992年 | 69篇 |
1991年 | 67篇 |
1990年 | 69篇 |
1989年 | 60篇 |
1988年 | 52篇 |
1985年 | 58篇 |
1982年 | 51篇 |
1981年 | 51篇 |
1979年 | 56篇 |
1967年 | 55篇 |
1965年 | 54篇 |
1964年 | 62篇 |
1963年 | 62篇 |
1962年 | 58篇 |
1961年 | 64篇 |
1960年 | 56篇 |
1959年 | 64篇 |
1958年 | 59篇 |
1957年 | 69篇 |
排序方式: 共有8431条查询结果,搜索用时 46 毫秒
41.
Material within the terrestrial environment is rarely homogeneously distributed, either spatially or temporally. One consequence of heterogeneity is that uncertainty is usually generated in measurements that are taken with the aim of characterising the environment. For example, a measurement of analyte concentration within soil taken from one sampling location on contaminated land can vary substantially when compared against another sample taken at effectively the same nominal location. The measurement uncertainty arising from the heterogeneity can substantially limit the reliability of the interpretations made upon environmental investigations. The sampling uncertainty usually outweighs the analytical uncertainty from the laboratory, often by a factor of 20 or more. One approach to reducing the uncertainty is to design a more suitable sampling strategy. This might be achieved by predicting the degree of heterogeneity prior to the investigation, but this is often difficult to achieve accurately. Another approach, which was investigated here, is to actually characterise the heterogeneity prior to the main investigation using rapid and inexpensive technology, such as in situ measurement techniques. In situ portable X-ray fluorescence (PXRF) and X-ray microprobe (XMP) techniques were employed to test the feasibility of this approach. Two contrasting contaminated land sites were chosen to characterise the two-dimensional spatial heterogeneity of heavy metal contamination in topsoil at a range of scales (50 m to 0.001 m). The spatial heterogeneity of contaminants, expressed as relative standard deviations, was found to differ between the two sites by a factor of two, largely due to the mode of deposition of pollution. The study also indicated that the heterogeneity did not change systematically with the scale of measurement between sampling locations at either site. 相似文献
42.
A. Haurie J.J.E. Kübler A. Clappier H. van den Bergh 《Environmental Modeling and Assessment》2004,9(1):1-12
A method is proposed to build integrated models (also called Metamodels) aimed at quantifying the economic efficiency of air quality policies. This Metamodeling approach is based on the coupling of two complementary models, that operate at different scales in space and time, and which represent the economic and the physical and chemical processes, respectively. The joint consideration of the physico-chemical and techno-economic structure of the pollution control problems permits a comprehensive evaluation of air pollution abatement strategies. The motivating pollution control problems include urban-regional air quality management through efficient energy and traffic control policies. A pilot study, exploiting data collected in the Geneva canton (Switzerland), is used to demonstrate the potential of the approach. 相似文献
43.
Multicriteria choice-methods, often used in policy analysis, were examined as a methodological procedure for eutrophication assessment. Multicriteria analysis ranked the sampling sites along two coastal areas, according to nutrient and chlorophyll concentrations. Three levels of nutrient loading were revealed, characterizing eutrophic, mesotrophic and oligotrophic waters. These results have been compared to station grouping based on multivariate analysis which indicated similar trends. Multicriteria choice-methods were shown to be an effective methodological tool in assessing eutrophication. In addition, this approach is compatible with multicriteria methods applied on policy-making and therefore the problem of eutrophication can be integrated with plan and project evaluation in environmental management. 相似文献
44.
Lenwood W. Hall Jr. William D. Killen Jr. Steven A. Fischer Michael C. Ziegenfuss Ronald D. Anderson Ronald J. Klauda 《Environmental monitoring and assessment》1994,31(3):233-257
The objective of this two-year study was to determine the efficacy of an automated limestone slurry doser to neutralize acidic pulses and improve water quality conditions for enhancing survival of early life stages of migratory fish species in a Maryland coastal plain stream. Implications for survival of early life stages of migratory fish species such as yellow perch (Perca flavescens), white perch (Morone americana), blueback herring (Alosa aestivalis) and alewife (Alosa pseudoharengus) are discussed based on the improved chemical conditions in the dosed area of the stream. Despite problems with overdosing in 1991 and failure of the stage transducer to work properly in 1992, the doser was generally effective in neutralizing acidic pulses (pH depressions) in the stream during three major rain events in both years. Chemical conditions (pH and inorganic monomeric aluminum) reported in the non-dosed area during major rainfall events were potentially stressful to both alewife and blueback herring although neither species was reported spawning in the stream during either year. Mitigating the potential impact of acidic conditions on early life stages of important migratory fish species was not sufficient to ensure spawning. It is therefore recommended that habitat improvement measures and well designed fish stocking programs be implemented concurrently with doser operations if the goal is to create optimum spawning conditions for migratory species. 相似文献
45.
Becker E. W. Bier W. Ehrfeld W. Schubert K. Schütte R. Seidel D. 《Die Naturwissenschaften》1976,63(9):407-411
The Science of Nature - The development of reliable manufacturing methods for commercial separation elements, the successful operation of separative stages, and extensive tests performed on plant... 相似文献
46.
Only three decades ago it was thought inconceivable that organic compounds could transport electric charges like metals do. However, recently organic molecules exhibiting high conductivities have been synthesized. Some examples of organic conductors are presented together with the present status of this research which is both interesting to chemists and physicists. Some applications of organic conductors are discussed. 相似文献
47.
E. Lamla F. Boschke G. Traving G. Pfotzer H. Wolter W. Walcher H. D. Dahmen H. J. Queisser W. W. Klingbeil K. Beyermann O. Müller R. R. Ernst D. Reinen H. Muth W. Becker G. Wunsch G. I. Distler L. Jaenicke H. G. v. Schnering H. Werner F. Reiff H. Schimassek W. Höll H. K. Vasil W. F. Angermeier W. Ruppel J. C. Eccles G. Spiteller H. Oettel W. Vogell P. Brosche K. J. Hsü H. -U. Schmincke 《Die Naturwissenschaften》1975,62(3):143-143
48.
49.
50.