全文获取类型
收费全文 | 30981篇 |
免费 | 358篇 |
国内免费 | 465篇 |
专业分类
安全科学 | 967篇 |
废物处理 | 1456篇 |
环保管理 | 3849篇 |
综合类 | 5144篇 |
基础理论 | 8078篇 |
环境理论 | 19篇 |
污染及防治 | 8197篇 |
评价与监测 | 2104篇 |
社会与环境 | 1805篇 |
灾害及防治 | 185篇 |
出版年
2023年 | 147篇 |
2022年 | 332篇 |
2021年 | 331篇 |
2020年 | 249篇 |
2019年 | 288篇 |
2018年 | 491篇 |
2017年 | 492篇 |
2016年 | 762篇 |
2015年 | 585篇 |
2014年 | 901篇 |
2013年 | 2486篇 |
2012年 | 1077篇 |
2011年 | 1467篇 |
2010年 | 1188篇 |
2009年 | 1225篇 |
2008年 | 1471篇 |
2007年 | 1520篇 |
2006年 | 1298篇 |
2005年 | 1123篇 |
2004年 | 1009篇 |
2003年 | 1093篇 |
2002年 | 968篇 |
2001年 | 1247篇 |
2000年 | 870篇 |
1999年 | 532篇 |
1998年 | 356篇 |
1997年 | 367篇 |
1996年 | 364篇 |
1995年 | 430篇 |
1994年 | 455篇 |
1993年 | 363篇 |
1992年 | 377篇 |
1991年 | 356篇 |
1990年 | 393篇 |
1989年 | 343篇 |
1988年 | 300篇 |
1987年 | 285篇 |
1986年 | 224篇 |
1985年 | 259篇 |
1984年 | 269篇 |
1983年 | 260篇 |
1982年 | 247篇 |
1981年 | 230篇 |
1980年 | 180篇 |
1979年 | 198篇 |
1978年 | 178篇 |
1975年 | 141篇 |
1974年 | 118篇 |
1972年 | 130篇 |
1971年 | 132篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
351.
352.
353.
354.
Until now no structured methodology existed for attuning environmental considerations to the business strategy of companies. The Environmental Competence Centre of Philips Sound & Vision in The Netherlands has developed and tested a methodology for this purpose. This methodology, called Selection of STRrategic Environmen Tal CHallenges (STRETCH), has proven to lead to promising results and should therefore be actively promoted. In this article, the authors show how the application of STRETCH provides the possibility of meeting three main objectives: First, focusing on the incorporation of environmental aspects into the company's business strategy can elicit innovations that may enhance the competitive position of the company by cost reduction and/or higher market shares. Second, the environmental opportunities and threats to be expected in the future can be anticipated in an earlier phase. Through this proactive approach a company can avoid external criticism and take the lead in environmental priority setting. Third, by applying the STRETCH methodology even higher eco-efficiencies are expected to be reached than through incremental, step-by-step environmental improvements. 相似文献
355.
More than 20000 handling manoeuvres in loading or unloading trailers in a large transportation company were observed. The aim of the study was to determine the frequency and nature of the incidents occurring whilst handling. The incidents were recorded and interpreted from a double perspective, namely as risk factors and as activity regulation factors. The study showed that on average, one incident occurred in every seven handling manoeuvres: 71% of them were related to the environment, and 29% to the activity. While numerous, the environment-related incidents were generally without consequences. In this respect, the activity incidents appeared more risky; also, the majority of these incidents occurred during the load positioning phase. The study also showed that loads are re-handled twice as often in unloading as in loading, the frequency of re-handlings varying widely from one handler to another. The reasons why so few of the observed incidents are reported in accident studies and their significance in the understanding of handling problems are discussed. 相似文献
356.
Kathleen M. Leonard Timothy LeDuc R.Kyle Mixon 《Waste management (New York, N.Y.)》1996,16(8):727-734
This paper describes a novel technology for the removal of solidified radioactive waste from underground storage tanks at the DOE Hanford site in southeast Washington. The process involves the use of a unique high pressure system which pulverizes the hardened saltcake with stainless steel pellets to a powder for easy vacuum removal. The steel pellets can be magnetically separated from the waste material for re-use. Specifically this study analyzes the effects of various steel abrasives, pressure of the air stream, and stand-off distance on removal rates and penetration depth on simulated saltcake samples using the high pressure technique. A full-scale test set-up and protocol were implemented to allow for comprehensive testing. To insure reproducibility of the method, tests were then run for the optimum removal parameters. A time-dependent test was also conducted to determine the relationship of removal rates to length of pressure blasts. The results of these tests revealed that stand-off distance and pressure could be positively correlated to removal volumes. Additionally, a statistical analysis confirmed that nozzle angle is independent of removal rate. This study demonstrated that the pellet ‘blaster’ technique is a safe, effective method for removal of radioactive wastes without any increase in either waste mass or volume. 相似文献
357.
Summary Quantitative studies on the biomethanation processes using a different biomass (goat dung, cow dung, buffalo dung, piggery waste, poultry waste and sewage) alone or in combination have been made. The dung samples have been found to be an efficient producer of biogas at a 1:2 dilution. Better yields of biogas are obtained in combination with other biomasses rather than when used alone. Judicious mixing of biomasses, however, is important. Competitive biomethanation of a biomass by other biomasses as a source for a wild population of microbes has been studied in vials using a cross-inoculation technique, i.e. using inoculum of one biomass on different sterile biomasses. The results show that the microbes are very specific and usually non-adaptive. Each inoculum outclasses others in using its natural biomass for methanation but reacts poorly when inoculated to other alien biomasses. Buffalo dung is to some extent adaptive in nature.Professor S.C. Lahiri is the senior author of this paper and he is ex-Head of the Department of Chemistry at the University of Kalyani where Nilanjan Chakravorty is a research fellow. Dr G.M. Sarkar is a senior lecturer in the Department of Botany at Ranaghat College, Ranaghat, Nadia, West Bengal, India. 相似文献
358.
Mark A. Harwell John F. Long Ann M. Bartuska John H. Gentile Christine C. Harwell Victoria Myers John C. Ogden 《Environmental management》1996,20(4):497-521
The ecosystems of South Florida are unique in the world. The defining features of the natural Everglades (large spatial scale, temporal patterns of water storage and sheetflow, and low nutrient levels) historically allowed a mosaic of habitats with characteristic animals. Massive hydrological alterations have halved the Everglades, and ecological sustainability requires fundamental changes in management.The US Man and the Biosphere Human-Dominated Systems Directorate is conducting a case study of South Florida using ecosystem management as a framework for exploring options for mutually dependent sustainability of society and the environment. A new methodology was developed to specify sustainability goals, characterize human factors affecting the ecosystem, and conduct scenario/consequence analyses to examine ecological and societal implications. South Florida has sufficient water for urban, agricultural, and ecological needs, but most water drains to the sea through the system of canals; thus, the issue is not competition for resources but storage and management of water. The goal is to reestablish the natural system for water quantity, timing, and distribution over a sufficient area to restore the essence of the Everglades.The societal sustainability in the Everglades Agricultural Area (EAA) is at risk because of soil degradation, vulnerability of sugar price supports, policies affecting Cuban sugar imports, and political/economic forces aligned against sugar production. One scenario suggested using the EAA for water storage while under private sugar production, thereby linking sustainability of the ecological system with societal sustainability. Further analyses are needed, but the US MAB project suggests achieving ecological sustainability consistent with societal sustainability may be feasible. 相似文献
359.
Corporations own approximately 25% of all private land in the United States and, therefore, play an essential role in protecting biodiversity and maintaining natural habitats. The Wildlife Habitat Council (WHC) is a unique joint venture between conservation organizations and corporations to utilize corporate lands for ensuring biodiversity. The following case studies demonstrate how corporations have helped ensure healthy ecosystems and provided critical leadership in regional efforts. Amoco Chemical Company's Cooper River Plant has been instrumental in developing a cooperative project that involves numerous corporations, plantation owners, private citizens, nonprofit organizations, government agencies, and community groups to develop a comprehensive, ecosystem-based management plan for part of the Cooper River in Charleston, South Carolina, USA. The second case focuses on the Morie Company, a national sand quarry operator headquartered in southern New Jersey, USA. Morie Company is working with WHC, community groups, the Pinelands Commission, and other state regulatory agencies to explore sustainable development opportunities for companies within the Pinelands regulations. The third case takes us to DuPont Company's Asturias, Spain, site. A win—win success story of improved habitat and cost savings is the result of DuPont's concern for the environment, ability to work with a variety of groups, and willingness to consider innovative restoration techniques. The fourth case discusses Consumers Power Company's Campbell Plant in West Olive, Michigan, USA. In addition to implementing projects that contribute to biodiversity, Consumers Power has developed an environmental education field station to teach others about the importance of natural habitats. The final case highlights Baltimore Gas & Electric Company's efforts to maintain habitat for endangered species at their Calvert Cliffs site in Maryland. 相似文献
360.