全文获取类型
收费全文 | 22967篇 |
免费 | 535篇 |
国内免费 | 3141篇 |
专业分类
安全科学 | 921篇 |
废物处理 | 1126篇 |
环保管理 | 2206篇 |
综合类 | 7808篇 |
基础理论 | 4811篇 |
环境理论 | 6篇 |
污染及防治 | 6765篇 |
评价与监测 | 1460篇 |
社会与环境 | 1118篇 |
灾害及防治 | 422篇 |
出版年
2023年 | 211篇 |
2022年 | 567篇 |
2021年 | 478篇 |
2020年 | 359篇 |
2019年 | 388篇 |
2018年 | 487篇 |
2017年 | 581篇 |
2016年 | 698篇 |
2015年 | 648篇 |
2014年 | 1039篇 |
2013年 | 1886篇 |
2012年 | 1166篇 |
2011年 | 1328篇 |
2010年 | 1045篇 |
2009年 | 1030篇 |
2008年 | 1191篇 |
2007年 | 1063篇 |
2006年 | 1019篇 |
2005年 | 837篇 |
2004年 | 719篇 |
2003年 | 771篇 |
2002年 | 730篇 |
2001年 | 816篇 |
2000年 | 640篇 |
1999年 | 545篇 |
1998年 | 373篇 |
1997年 | 385篇 |
1996年 | 361篇 |
1995年 | 340篇 |
1994年 | 295篇 |
1993年 | 248篇 |
1992年 | 268篇 |
1991年 | 252篇 |
1990年 | 202篇 |
1989年 | 175篇 |
1988年 | 180篇 |
1987年 | 112篇 |
1986年 | 142篇 |
1985年 | 137篇 |
1984年 | 127篇 |
1983年 | 118篇 |
1982年 | 129篇 |
1981年 | 126篇 |
1979年 | 101篇 |
1978年 | 102篇 |
1976年 | 93篇 |
1974年 | 105篇 |
1972年 | 89篇 |
1967年 | 100篇 |
1964年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 487 毫秒
91.
Carl W. Chen 《Journal of the American Water Resources Association》2003,39(6):1561-1562
92.
93.
94.
Living veligers of the Cassoidea have been observed to use a mantle appendage to form and resorb periostracum. Anatomical and histological examinations of a ranellid (Cymatium sp.) larva collected from the Red Sea in 1987 revealed the structure and location of the pallial appendage. The mantle edges of juvenile or adult species of the Cassoidea do not show a comparable specialization. It is demonstrated that cassoid larval conch characters are sufficient to prove the existence of a pallial appendage without anatomical confirmation. A mantle appendage is not known from teleplanic (long-living planktic) veligers of other gastropod superfamilies. In cases where the larval strategies of the latter are known they are totally different. Therefore it is suggested that the adaptation of cassoid larvae to pelagic life is unique among gastropods representing an autapomorphic character of the superfamily. 相似文献
95.
This paper examines the relationship between survivor reactions to a downsizing and retention subsequent to a downsizing. We hypothesize that survivors who experience the downsizing as distributively, procedurally, and interactionally just and who see top management as trustworthy will feel more attached to the organization because each reduces the threat inherent in downsizing. In addition, we hypothesize that survivors who feel empowered will also feel more attached to the organization because they feel better able to cope with the downsizing. We further hypothesize that those survivors who feel more attached to the organization following the downsizing will be more likely to remain with the organization in the coming year. The theoretical model is tested on a sample of aerospace employees who survived an organizational downsizing. The trustworthiness of management, distributive justice, procedural justice, and three dimensions of empowerment are found to facilitate more organizational attachment. Higher levels of attachment are found, in turn, to facilitate less voluntary turnover in the year following the downsizing. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
96.
97.
Stormwater runoff is now a major contributor to the pollution of coastal waters in the United States. Public agencies are responding by requiring stormwater monitoring to satisfy the National Pollutant Discharge Elimination System stormwater permit. However, studies to understand the utility of the current programs or to improve their usefulness have not yet been performed. In this paper, we evaluate the land-use-based program, the industrial stormwater permit program, and beach water-quality monitoring in the County of Los Angeles, California, to determine if the results will be helpful to planners and regulators in abating stormwater pollution. The utility of the program has been assessed based on the programs' ability to accurately estimate the emissions for different classes of land use. The land-use program appears successful, while the industrial monitoring program does not. Beach water-quality monitoring suffers from a lack of real-time monitoring techniques. We also provide suggested improvements, such as sampling method and time, and parameter selection. 相似文献
98.
99.
100.
The coastal water of northeast Taiwan island, called 'Yin-Yang Hai' for its distinct yellow colour compared with blue offshore water, was investigated from 1989 to 1990 by the authors. Biological study showed the dominant species of plankton to be Copepoda, Cladocera, planktonic eggs and Diatoma. Dominant species of benthos were young crabs, Amphipoda and Annelida, with Amphipoda usually occurring in heavily polluted areas. Heavy metal data showed that the concentration of copper was high. the copper and iron concentration in algae of the intertidal zone was also high. the concentrations of iron and copper in inshore water were also higher than in offshore water. By comparison of the pH and salinity distribution of this area, we conclude that this coastal water has been polluted by acid waste water from coastal industry. the suspended solids concentration in sea water is high. Flocculation occurring at the boundary of fresh and saline water might be a reason for the distinct yellow colour of the water of this area. Further study is required. 相似文献