全文获取类型
收费全文 | 42742篇 |
免费 | 568篇 |
国内免费 | 804篇 |
专业分类
安全科学 | 1466篇 |
废物处理 | 1920篇 |
环保管理 | 5746篇 |
综合类 | 7234篇 |
基础理论 | 11136篇 |
环境理论 | 25篇 |
污染及防治 | 11122篇 |
评价与监测 | 2713篇 |
社会与环境 | 2465篇 |
灾害及防治 | 287篇 |
出版年
2023年 | 212篇 |
2022年 | 439篇 |
2021年 | 443篇 |
2020年 | 388篇 |
2019年 | 390篇 |
2018年 | 682篇 |
2017年 | 684篇 |
2016年 | 1031篇 |
2015年 | 805篇 |
2014年 | 1175篇 |
2013年 | 3432篇 |
2012年 | 1507篇 |
2011年 | 2060篇 |
2010年 | 1654篇 |
2009年 | 1728篇 |
2008年 | 2018篇 |
2007年 | 2055篇 |
2006年 | 1766篇 |
2005年 | 1487篇 |
2004年 | 1403篇 |
2003年 | 1457篇 |
2002年 | 1314篇 |
2001年 | 1631篇 |
2000年 | 1203篇 |
1999年 | 744篇 |
1998年 | 501篇 |
1997年 | 526篇 |
1996年 | 522篇 |
1995年 | 603篇 |
1994年 | 583篇 |
1993年 | 507篇 |
1992年 | 498篇 |
1991年 | 489篇 |
1990年 | 512篇 |
1989年 | 466篇 |
1988年 | 403篇 |
1987年 | 382篇 |
1986年 | 347篇 |
1985年 | 357篇 |
1984年 | 418篇 |
1983年 | 373篇 |
1982年 | 375篇 |
1981年 | 340篇 |
1980年 | 276篇 |
1979年 | 307篇 |
1978年 | 246篇 |
1977年 | 204篇 |
1975年 | 208篇 |
1974年 | 196篇 |
1972年 | 211篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
141.
Although oil spill cleanup requirements have existed in the United States for years, recent increases in oil imports and marine transportation of petroleum products as well as growing environmental concern have exposed a new industry, the Oil Spill Cleanup Industry. This paper explores some of the microeconomic aspects of this industry which has come under increased scrutiny by the general public, big business, and the federal government.In addition to a brief history and definition, several basic questions about the economic viability of the oil spill cleanup industry are raised and explored, and the impact on the industry of cleanup from government sources is examined, both from the perspective of present operations and from apparent future increases in federal participation. The primary dilemma facing the industry, that of providing continued and immediate supply while confronted with stochastic demand, is discussed. The effects of the large spill on the industry both in terms of revenue and ability to meet cleanup requirements is also considered.Information for the paper is drawn from past and continuing involvement in the U.S. Coast Guard's Marine Environmental Protection Program by both authors. The statistical evidence presented here was compiled through personal interviews and from two computerized Coast Guard information systems; PIRS (the Pollution Incident Reporting System), and SKIM (the Spill Cleanup Equipment Inventory System). 相似文献
142.
143.
144.
145.
146.
This paper describes the help given by the social services department of a shipping company to bereaved families following a shipping disaster. In the absence of clear, factual and prompt information from an authoritative source, there is a tendency for bereaved individuals to deny their loss and thereby delay the process of mourning and eventual recovery. Appropriate intervention and support can help to overcome this tendency as was seen in the Madasa case. 相似文献
147.
148.
Gunavant M. Oza 《The Environmentalist》2003,23(2):189-192
Much of the forest wealth on the plains and in the hilly areas of India has been foolishly destroyed, and the rich heritage of wildlife has been slaughtered mostly for only temporary gain. The wanton axing of the larger indigenous trees and the uprooting of other floristic elements in the hills and on the lower slopes of the mountains, gradually impoverishes them, and may be followed by erosion that ultimately leaves the slopes barren. These alarming threats to the chir (Pinus roxburghii) and fir (Abies pindrow) forests of Kashmir will have disastrous consequences. Once densely-forested, the mountain slopes in Kashmir have become largely naked through too-heavy tapping and cutting of the trees; with concomitant landslides, frequent floods, and loss of fertile topsoil. Unfortunately, the people living in the areas of the chir and fir trees, do not play a proper part in their protection, and the last two decades have witnessed, year by year, the rapid march of urbanization and manifold destructive activities which have taken a heavy toll on these precious species. Urgent conservation measures are essential to preserve these endangered trees in Kashmir. 相似文献
149.
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
150.
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