首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30219篇
  免费   333篇
  国内免费   233篇
安全科学   874篇
废物处理   1079篇
环保管理   4217篇
综合类   4751篇
基础理论   8738篇
环境理论   23篇
污染及防治   7832篇
评价与监测   1794篇
社会与环境   1273篇
灾害及防治   204篇
  2022年   183篇
  2021年   182篇
  2019年   226篇
  2018年   406篇
  2017年   398篇
  2016年   586篇
  2015年   506篇
  2014年   698篇
  2013年   2177篇
  2012年   866篇
  2011年   1301篇
  2010年   1049篇
  2009年   1073篇
  2008年   1278篇
  2007年   1370篇
  2006年   1209篇
  2005年   1036篇
  2004年   1033篇
  2003年   965篇
  2002年   959篇
  2001年   1256篇
  2000年   874篇
  1999年   562篇
  1998年   440篇
  1997年   442篇
  1996年   458篇
  1995年   494篇
  1994年   450篇
  1993年   408篇
  1992年   422篇
  1991年   379篇
  1990年   385篇
  1989年   418篇
  1988年   358篇
  1987年   304篇
  1986年   277篇
  1985年   313篇
  1984年   297篇
  1983年   334篇
  1982年   329篇
  1981年   276篇
  1980年   246篇
  1979年   274篇
  1978年   233篇
  1977年   199篇
  1976年   203篇
  1975年   195篇
  1974年   175篇
  1973年   172篇
  1972年   202篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
671.
672.
This paper demonstrates empirically the gain from adopting more general equilibrium approaches in projecting the effects on domestic output and international trade of environmental controls. The suggested models include a partial equilibrium case where all industries are treated independently, an intermediate case incorporating effects in supplying industries, and general equilibrium formulations based on alternative macroeconomic conditions. U. S. data is used to evaluate these models. Under both pollutor pays and subsidy financing schemes, moving from the simplest case to the intermediate model results in quite different industry projections. Including macroeconomic factors appears particularly important in the classical setting.  相似文献   
673.
Involuntary eye movements in salamanders   总被引:1,自引:0,他引:1  
  相似文献   
674.
Taylor AJ 《Disasters》1983,7(1):37-40
This paper defines the various levels within government, the voluntary agencies and the community which might benefit from training and makes suggestions as to where the emphasis should be placed. It points out that training programmes should be designed to meet the expressed needs of a particular group of trainees as well as be related to the current or potential disaster situation.  相似文献   
675.
676.
Snarr DN  Brown EL 《Disasters》1979,3(3):287-292
To some degree it is unfair to evaluate a post-disaster housing program as to its effectiveness in decreasing vulnerability and preventing future disasters. As Burton states, "With rare exceptions, administrators and techniques have been trained to cope with disaster rather than to prevent it" [reference (2), p.197]. These were certainly not goals articulated by the agency responsible for constructing housing after Fifi. However, the authors feel that failure to evaluate specific projects by persons knowledgeable of the projects functioning, will only forestall the shift which Cuny calls for, "… from disaster response to disaster mitigation and prevention" [reference (4), p.123). In doing this we hope to add some specific case study data to the growing literature on disaster mitigation and prevention. Disaster vulnerability in Honduras is overwhelmingly related to flooding. More crucial than the materials and construction of housing is the issue of siting. If appropriately sited, houses made of bajarique, wood, or concrete block are able to withstand the heavy rains associated with a hurricane. Regarding the siting of the projects, the Honduras Project clearly has one positive and one negative accomplishment in the cases of Santa Rica and Flores, respectively. San Jose is less clear but is certainly a much safer site than those formerly occupied by the residents, in that there is no danger of flooding. The present site was not flooded during Fifi nor did it experience mudslides. However, the future is not so clear regarding the latter. Within the village proper a large amount of vegetation has been added which will tend to stabilise the soil on the steeper slopes. The streets, however, are seriously eroded and probably can not be maintained for vehicle usage, which does not pose a serious problem to the residents as none possess automobiles or trucks. One large gully bisects the village and receives run-off from the adjacent hills. It has been expanding, which would suggest that the slopes above the village could prove problematic in case of a Fifi-sized storm. Flores is located on a very poor site in reference to prevention and mitigation. It is located in a portion of the Sula Valley which is prone to flooding and, as mentioned before, was inundated by over 2m of water during hurricane Fifi. No prevention techniques were possible by NAEA/HEA and the houses were built on earthen mounds barely adequate to keep water out during the rainy season. The nearby dike which could possibly provide protection is non-functional due to poor maintainance. Given a storm of Fifi's magnitude, or possibly smaller, this site will again be flooded. Santa Rica is clearly well sited concerning flooding: it did not experience flooding during Fifi and is not flood prone. However, houses did experience some wall damage due to earthquakes following and associated with the Guatemalan quake of 1976. Due to the size and nature of the latter much "re-adjustment" occurred in the neighbouring fault system; however, damage to the houses was all superficial. We feel the residents were vocal about their concern due to the severity of the Guatemalan disaster and their lack of experience with concrete block houses. That the two sites (particularly Flores and partially San Jose) are vulnerable to future disasters cannot be considered solely the fault of an outside agency without local knowledge and understanding. In the engineering report issued during the construction it was explicitly stated that in Flores, "Future flooding remains a danger," [reference (6), p.49]. The future residents of Flores had gained access to the land from the National Agrarian Institute and were anxious to receive assistance in building homes. In fact, CARE, which had previously given these people tin roofing for houses, was threatening to take it back since the people had not yet started building. NAEA/HEA were responding to people in a rather desperate situation. But, on the other hand, they were responding to people who had been promised (not given) land by an agency of the Honduran national government which would be cognizant of the potential flooding at this site. Likewise, in San Jose, where mudslides and erosion remain a threat, the land was provided by a local government agency, the municipality. Although our goal in this discussion has not been to establish blame, we feel it imperative to mention the sequence of events that resulted in the questionable siting of Flores and San Jose. It is very easy and often accurate to place blame on outsiders who lack sophistication and knowledge about such matters. In this case local input did not result in post-disaster planning that is actually precautionary. This, we feel, illustrates the extreme complexity of cross-cultural aid, especially in the post-disaster period. It also points to the need for precautionary planning with reference to permanent post-disaster reconstruction.  相似文献   
677.
678.
679.
680.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号