全文获取类型
收费全文 | 10365篇 |
免费 | 835篇 |
国内免费 | 2512篇 |
专业分类
安全科学 | 517篇 |
废物处理 | 337篇 |
环保管理 | 2357篇 |
综合类 | 6037篇 |
基础理论 | 1338篇 |
环境理论 | 6篇 |
污染及防治 | 928篇 |
评价与监测 | 281篇 |
社会与环境 | 1733篇 |
灾害及防治 | 178篇 |
出版年
2024年 | 66篇 |
2023年 | 206篇 |
2022年 | 372篇 |
2021年 | 366篇 |
2020年 | 328篇 |
2019年 | 339篇 |
2018年 | 336篇 |
2017年 | 417篇 |
2016年 | 477篇 |
2015年 | 469篇 |
2014年 | 530篇 |
2013年 | 970篇 |
2012年 | 894篇 |
2011年 | 942篇 |
2010年 | 628篇 |
2009年 | 571篇 |
2008年 | 496篇 |
2007年 | 680篇 |
2006年 | 703篇 |
2005年 | 502篇 |
2004年 | 456篇 |
2003年 | 442篇 |
2002年 | 403篇 |
2001年 | 346篇 |
2000年 | 359篇 |
1999年 | 282篇 |
1998年 | 212篇 |
1997年 | 181篇 |
1996年 | 147篇 |
1995年 | 111篇 |
1994年 | 105篇 |
1993年 | 93篇 |
1992年 | 66篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1973年 | 5篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
281.
Subsidence is a primary factor governing marsh deterioration in Mississippi River deltaic plain coastal marshes. Marsh surface-water level relationships are maintained primarily through soil organic matter accumulation and inorganic sediment input. In this study we examined the role of soil organic matter accumulation in maintaining marsh elevation in a brackish Spartina patens marsh. Measured rates of soil organic accumulation were compared to plant biomass production and soil respiration (carbon dioxide and methane emission) at the study sites. The study demonstrated the importance of plant biomass production to soil organic carbon accumulation in maintaining viable Spartina patens marshes in sediment-deficient coastal environments. The role of Mississippi River freshwater reintroduction in maintaining conditions for organic accretion is discussed. 相似文献
282.
Georgios E. Pavlikakis Vassilios A. Tsihrintzis 《Journal of the American Water Resources Association》2003,39(2):277-288
ABSTRACT: The Ecosystem Management (EM) process belongs to the category of Multi‐Criteria Decision Making (MCDM) problems. It requires appropriate decision support systems (DSS) where “all interested people” would be involved in the decision making process. Environmental values critical to EM, such as the biological diversity, health, productivity and sustainability, have to be studied, and play an important role in modeling the ecosystem functions; human values and preferences also influence decision making. Public participation in decision and policy making is one of the elements that differentiate EM from the traditional methods of management. Here, a methodology is presented on how to quantify human preferences in EM decision making. The case study of the National Park of River Nestos Delta and Lakes Vistonida and Ismarida in Greece, presented as an application of this methodology, shows that the direct involvement of the public, the quantification of its preferences and the decision maker's attitude provide a strong tool to the EM decision making process. Public preferences have been given certain weights and three MCDM methods, namely, the Expected Utility Method, Compromise Programming and the Analytic Hierarchy Process, have been used to select alternative management solutions that lead to the best configuration of the ecosystem and are also socially acceptable. 相似文献
283.
Jon E. Schoonover Karl W. J. Williard 《Journal of the American Water Resources Association》2003,39(2):347-354
ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone. 相似文献
284.
介绍了活性灭火剂(ACP)的历史发展、灭火原理、配方原则、对配方要求和使用场合。可使读者对ACP获得较全面的了解。 相似文献
285.
286.
泥石流输沙对小江中下游河床演变的影响 总被引:4,自引:1,他引:4
对小江中下游近90km河床及两岸泥石流进行了调查研究。得到:泥石流输沙年际和季节变化大;泥石流高强度的输沙造成小江河床特殊的平面和剖面特征;泥石流堵塞小江河道,对纵比降有再造作用;泥沙使小江河床以年均20cm~50cm速度抬升。 相似文献
287.
288.
289.
文章对加快顺德市城市化进程的障碍因子和优势条件进行了分析,认为“滞后城市化”是经济增长和产业发展的主要瓶颈,并提出加快顺德城市化进程的优势条件已成熟,必须抓住机遇,确立发展目标,走可持续发展的城市化道路。 相似文献
290.
徐州市具有特色鲜明的历史文化资源和极其优越的开发条件。作者根据旅游资源可持续发展的相关原则,分析了徐州市在历史文化资源开发中存在的问题,提出了充分,合理开发利用当地历史文化资源的主要对策。 相似文献