全文获取类型
收费全文 | 94727篇 |
免费 | 1225篇 |
国内免费 | 1118篇 |
专业分类
安全科学 | 3831篇 |
废物处理 | 3478篇 |
环保管理 | 14514篇 |
综合类 | 21256篇 |
基础理论 | 26979篇 |
环境理论 | 74篇 |
污染及防治 | 16676篇 |
评价与监测 | 5699篇 |
社会与环境 | 3957篇 |
灾害及防治 | 606篇 |
出版年
2022年 | 819篇 |
2021年 | 808篇 |
2020年 | 652篇 |
2019年 | 861篇 |
2018年 | 1182篇 |
2017年 | 1239篇 |
2016年 | 2201篇 |
2015年 | 1838篇 |
2014年 | 2568篇 |
2013年 | 9241篇 |
2012年 | 2396篇 |
2011年 | 2797篇 |
2010年 | 3349篇 |
2009年 | 3512篇 |
2008年 | 2357篇 |
2007年 | 2275篇 |
2006年 | 2608篇 |
2005年 | 2498篇 |
2004年 | 2764篇 |
2003年 | 2639篇 |
2002年 | 2185篇 |
2001年 | 2510篇 |
2000年 | 2127篇 |
1999年 | 1567篇 |
1998年 | 1385篇 |
1997年 | 1381篇 |
1996年 | 1508篇 |
1995年 | 1609篇 |
1994年 | 1490篇 |
1993年 | 1359篇 |
1992年 | 1347篇 |
1991年 | 1313篇 |
1990年 | 1278篇 |
1989年 | 1246篇 |
1988年 | 1079篇 |
1987年 | 1004篇 |
1986年 | 998篇 |
1985年 | 1082篇 |
1984年 | 1170篇 |
1983年 | 1187篇 |
1982年 | 1183篇 |
1981年 | 1112篇 |
1980年 | 951篇 |
1979年 | 956篇 |
1978年 | 832篇 |
1977年 | 728篇 |
1976年 | 656篇 |
1974年 | 645篇 |
1973年 | 676篇 |
1972年 | 680篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Pollution due to persistent pesticides is not a regional but a global problem. Organochlorine pesticides are persistent chemicals, stored and accumulated in the tissues of a wide variety of invertebrates and vertebrates including marine species. In the present study the organochlorine residues HCHs, DDTs and PCBs were measured in different trophic groups of birds (scavengers, inland piscivores, coastal piscivores, insectivores, granivores and omnivores) collected from Tamil Nadu Coast, India. The residue accumulation as a function of sex did not depict distinct variation. However, females had lower residue levels than males in terms of their mean weight and feeding habits. A continuous monitoring programme is recommended to establish the studied organisms as indicator species. 相似文献
133.
The amount of NO2 and NO produced by the machine smoking of cigarettes was determined for 15 commercial Canadian brands. Average yield of NO was 1.44 μmoles or about 13% of the average reported for American cigarettes. Levels of NO2 were less than 12% of NO and were probably due to the oxidation of NO. In order to assess the contribution of tobacco smoke to levels of NO in ambient air, 5 brands of cigarettes were smoked in 27 cubic meter controlled environment room. Ventilation conditions were either 2.5 or 5.0 air changes per hour (ACH) and each experiment was replicated 3 times for a total of 30 experiments. Ventilation rates of 0.3 and 1.5 ACH were also selected in a second series of experiments in which only one brand of cigarette was smoked. Least squares estimates for the effective ventilation rates were obtained in the usual manner after linearizing the decay portion of the NO time curve. In each of the experiments, the regression explained at least 95% of the variation in the levels of NO with time. Loss of NO due to factors other than ventilation appeared to be constant within experimental error and averaged 2.22 ACH. Equilibrium values for NO were grossly underestimated when results from currently accepted proecedures for smoke analysis were used in modeling the growth and decay of NO. Goodness-of-fit was improved when equilibrium values were estimated based on observed levels in ambient air. This approach may be more suitable for evaluating the potential contribution of cigarette smoke to levels of indoor air pollutants. 相似文献
134.
135.
136.
137.
138.
M. Marcelli M. Caburazzi A. Perilli V. Piermattei E. Fresi 《Chemistry and Ecology》2005,21(5):351-367
The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between the Italian and the Sardinian coasts during the Astraea 2 cruise (6-7 and 26-27 September 1995), studying the deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in the upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In the first section, the cyclone presents a double doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, the second section shows that the gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving the importance of TUVs in the study of mesoscale processes. 相似文献
139.
140.