全文获取类型
收费全文 | 4774篇 |
免费 | 328篇 |
国内免费 | 383篇 |
专业分类
安全科学 | 795篇 |
废物处理 | 33篇 |
环保管理 | 957篇 |
综合类 | 1917篇 |
基础理论 | 373篇 |
环境理论 | 3篇 |
污染及防治 | 328篇 |
评价与监测 | 707篇 |
社会与环境 | 209篇 |
灾害及防治 | 163篇 |
出版年
2024年 | 13篇 |
2023年 | 103篇 |
2022年 | 152篇 |
2021年 | 203篇 |
2020年 | 204篇 |
2019年 | 125篇 |
2018年 | 111篇 |
2017年 | 153篇 |
2016年 | 180篇 |
2015年 | 207篇 |
2014年 | 214篇 |
2013年 | 233篇 |
2012年 | 265篇 |
2011年 | 358篇 |
2010年 | 188篇 |
2009年 | 332篇 |
2008年 | 268篇 |
2007年 | 293篇 |
2006年 | 248篇 |
2005年 | 203篇 |
2004年 | 172篇 |
2003年 | 169篇 |
2002年 | 153篇 |
2001年 | 124篇 |
2000年 | 113篇 |
1999年 | 105篇 |
1998年 | 101篇 |
1997年 | 76篇 |
1996年 | 52篇 |
1995年 | 62篇 |
1994年 | 75篇 |
1993年 | 45篇 |
1992年 | 26篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1969年 | 3篇 |
排序方式: 共有5485条查询结果,搜索用时 437 毫秒
141.
孟玲 《中国环境管理干部学院学报》2003,13(2):17-19
本文分析了玻璃生产企业废水的来源,并从耀华玻璃集团实施的废水治理项目的实际出发,阐述了废水经过治理后综合利用的途径,实现废水的零排放,减少环境污染,节约水资源。 相似文献
142.
连云港市地处欧亚大陆桥的东桥头堡,是沿海十四个开放城市之一,国家定位是将其建设成为连接太平洋沿岸与中亚地区的国际商贸中心和全国性的旅游城市。而目前的山丘区水土流失严重,植被稀少,生态环境恶化,与国家定位目标和连云港市发展目标相差甚远。因此在制定水土保持生态环境建设规划时,必须紧紧围绕改善生态环境这条主线,以增加农民收入和改善生存条件为突破口,因地制宜,坚持长期综合治理,方能实现“山川秀美”之目标。 相似文献
143.
Eugene L. Peck 《Journal of the American Water Resources Association》1997,33(1):125-134
ABSTRACT: Many users of hydrometeorological records are not aware of the number of inconsistencies and biases that occur in hydrometeorological records. Examples are presented illustrating how the exposures of sites for measurement of precipitation, wind, snow on the ground, and evaporation determine to a large extent how useful the records are for estimating areal conditions. For areas where precipitation in the form of snow produces a significant portion of the runoff, a smaller number of quality records may be more valuable for modeling than a much larger number of records of lower quality. Information is presented to show that the overall value of an operational hydrometeorological network is dependent upon how consistent and representative of average conditions the collected records are, especially for mountainous areas in cold regions. 相似文献
144.
John H. Martin 《Journal of the American Water Resources Association》1997,33(4):741-753
ABSTRACT: On May 19, 1993, a jury in the U.S. District Court for the Western District of New York found Southview Farm and Richard H. Popp guilty of violating the Clean Water Act on five occasions. The violations were the result of storm water runoff from a site used for disposal of dairy cattle manure from an unpermitted concentrated animal feeding operation. The presiding District Court judge later dismissed the jury verdict, and subsequently a U.S. Court of Appeals for the Second Circuit reversed the dismissal. The Court of Appeals concluded that the discharges were not exempt as agricultural storm water discharges, and that the manure spreaders involved were point sources. Because the use of animal manures in crop production activities will result, unavoidably, in the discharge of some pollutants to adjacent surface waters, a rational and universally applicable basis is needed to determine when such discharges are point versus nonpoint source. Current statutes and regulations do not delineate clearly such a boundary. To address this lack of specificity, I propose that application rates be based on recommended crop nutrient needs. 相似文献
145.
神经网络及其在水库调洪演算中的应用 总被引:8,自引:0,他引:8
结合洪水灾害管理的特点建立了水库调洪演算的人工神经网络模型,阐述了其基本原理及算法,并结合某水库调洪演算实例说明了其应用。 相似文献
146.
污染物对水环境的影响主要发生在枯水期,此时水流状态处于稳态.Streeter-phelps(S-P)方程能预测简单稳态条件下的水质状况,并具有较高的计算织亏的精度. 相似文献
147.
148.
我国是一个水资源十分短缺的国家,加强水资源管理刻不容缓。为此,本文结合我国水资源管理的实际状况,从思想、组织、方法、手段等方面分别论述了加强水资源系统管理的必要性和可能性。 相似文献
149.
Bangladesh is a very flat delta built up by the Ganges—Brahmaputra—Meghna/Barak river systems. Because of its geographical location, floods cause huge destruction of lives and properties almost every year. Water control programs have been undertaken to enhance development through mitigating the threat of disasters. This structural approach to flood hazard has severely affected floodplain fisheries that supply the major share of protein to rural Bangladesh, as exemplified by the Chandpur Irrigation Project. Although the regulated environment of the Chandpur project has become favorable for closed-water cultured fish farming, the natural open-water fishery loss has been substantial. Results from research show that fish yields were better under preproject conditions. Under project conditions per capita fish consumption has dropped significantly, and the price of fish has risen beyond the means of the poor people, so that fish protein in the diet of poor people is gradually declining. Bangladesh is planning to expand water control facilities to the remaining flood-prone areas in the next 15–20 years. This will cause further loss of floodplain fisheries. If prices for closed-water fish remain beyond the buying power of the poor, alternative sources of cheap protein will be required. 相似文献
150.
Wetland loss and substitution by the Section 404 permit program in southern California,USA 总被引:1,自引:0,他引:1
To test the effectiveness of the 404 permit program in preventing a net loss of wetland resources, 75 Section 404 projects permitted in the years 1987–1989 and located in a portion of southern California were evaluated. From this group of projects, 80.47 ha of wetlands were affected by Section 404 permits and the Army Corps of Engineers required 111.62 ha of wetland mitigation. To verify the successful completion of each mitigation project, all 75 project sites were visited and evaluated based on the amount of dead vegetation, growth and coverage, and the number of invasive species. Based on the field verification results, the actual amount of completed mitigation area was 77.33 ha, resulting in a net loss of 3.14 ha of wetland resources in the years 1987–1989. By comparing the types of wetlands lost to the types of wetlands mitigated, it is apparent that, in particular, freshwater wetlands are experiencing a disproportionately greater loss of area and that riparian woodland wetlands are most often used in mitigation efforts. The net result of these accumulated actions is an overall substitution of wetland types throughout the region. Results also indicate that, typically, large-scale mitigation projects are more successful compared to smaller projects and that successful compliance efforts are not evenly distributed throughout the region. We recommend that better monitoring, mitigation in-kind, mitigation banking, and planning on a regional or watershed scale could greatly improve the effectiveness of the Section 404 permitting program. 相似文献