全文获取类型
收费全文 | 17902篇 |
免费 | 244篇 |
国内免费 | 179篇 |
专业分类
安全科学 | 576篇 |
废物处理 | 581篇 |
环保管理 | 3212篇 |
综合类 | 3702篇 |
基础理论 | 4232篇 |
环境理论 | 13篇 |
污染及防治 | 4433篇 |
评价与监测 | 893篇 |
社会与环境 | 561篇 |
灾害及防治 | 122篇 |
出版年
2021年 | 120篇 |
2019年 | 143篇 |
2018年 | 219篇 |
2017年 | 223篇 |
2016年 | 308篇 |
2015年 | 272篇 |
2014年 | 314篇 |
2013年 | 1491篇 |
2012年 | 486篇 |
2011年 | 694篇 |
2010年 | 500篇 |
2009年 | 611篇 |
2008年 | 705篇 |
2007年 | 738篇 |
2006年 | 668篇 |
2005年 | 500篇 |
2004年 | 521篇 |
2003年 | 570篇 |
2002年 | 496篇 |
2001年 | 547篇 |
2000年 | 416篇 |
1999年 | 312篇 |
1998年 | 225篇 |
1997年 | 209篇 |
1996年 | 250篇 |
1995年 | 253篇 |
1994年 | 265篇 |
1993年 | 244篇 |
1992年 | 252篇 |
1991年 | 222篇 |
1990年 | 258篇 |
1989年 | 232篇 |
1988年 | 194篇 |
1987年 | 203篇 |
1986年 | 188篇 |
1985年 | 205篇 |
1984年 | 192篇 |
1983年 | 210篇 |
1982年 | 198篇 |
1981年 | 210篇 |
1980年 | 187篇 |
1979年 | 168篇 |
1978年 | 164篇 |
1977年 | 146篇 |
1976年 | 148篇 |
1975年 | 126篇 |
1974年 | 148篇 |
1973年 | 133篇 |
1972年 | 132篇 |
1967年 | 119篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
John F. Potter 《The Environmentalist》2006,26(4):329-329
32.
33.
34.
35.
Carl W. Chen 《Journal of the American Water Resources Association》2003,39(6):1561-1562
36.
37.
38.
David W. Mehlman 《Conservation biology》1994,8(4):1141-1145
39.
In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General Interest; 3 Normal Fetal Development; 4 Gametogenesis and Pre-implantation Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Diagnosis by Ultrasound and Other Imaging; 8 Maternal Screening; 9 Screening for Carriers of Genetic Abnormality; 10 Technological Developments; 11 Confined Placental Mosaicism and Uniparental Disomy; 12 Molecular Cytogenetics; 13 Fetal Cells in Maternal Circulation; 14 Fetal Therapy; 15 Psychosocial Aspects; 16 Epidemiology and Environmental Factors; 17 Developmental Pathology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted 相似文献
40.
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