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   39050篇
  免费   422篇
  国内免费   309篇
安全科学   1126篇
废物处理   1357篇
环保管理   5454篇
综合类   7266篇
基础理论   10702篇
环境理论   28篇
污染及防治   9989篇
评价与监测   2131篇
社会与环境   1470篇
灾害及防治   258篇
  2021年   232篇
  2019年   277篇
  2018年   480篇
  2017年   478篇
  2016年   697篇
  2015年   602篇
  2014年   818篇
  2013年   2873篇
  2012年   1070篇
  2011年   1582篇
  2010年   1258篇
  2009年   1331篇
  2008年   1579篇
  2007年   1655篇
  2006年   1493篇
  2005年   1230篇
  2004年   1230篇
  2003年   1194篇
  2002年   1151篇
  2001年   1525篇
  2000年   1057篇
  1999年   707篇
  1998年   532篇
  1997年   528篇
  1996年   577篇
  1995年   590篇
  1994年   573篇
  1993年   514篇
  1992年   536篇
  1991年   500篇
  1990年   516篇
  1989年   543篇
  1988年   460篇
  1987年   414篇
  1986年   387篇
  1985年   425篇
  1984年   397篇
  1983年   434篇
  1982年   433篇
  1981年   390篇
  1980年   355篇
  1979年   377篇
  1978年   337篇
  1977年   285篇
  1976年   299篇
  1975年   261篇
  1974年   283篇
  1973年   270篇
  1972年   290篇
  1970年   224篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
941.
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   
942.
Carter W 《Disasters》1983,7(1):34-36
This paper discusses both the need for training within a wider context of community disaster preparedness and the major alternatives in methods of training. Emphasis is placed on the importance of compatibility between the resources within a given country and appropriate training programmes.  相似文献   
943.
Hodler TW 《Disasters》1982,6(1):44-49
A survey was conducted of individuals residing directly in the path of the tornado that hit Kalamazoo, Michigan, on 13th May 1980. The residents' tornado preparedness and response were examined in an effort to evaluate the city's emergency warning system. The system was adequate for people on the east side of the city and lacking for west side residents. Other factors pertaining to the storm event and human response were also evaluated.  相似文献   
944.
945.
946.
947.
948.
949.
Recovering dense nonaqueous‐phase liquid (DNAPL) remains one of the most difficult problems facing the remediation industry. Still, the most common method of recovering DNAPL is to physically remove the contaminants using common technologies such as total fluids recovery pumps, vacuum systems, and “pump‐and‐treat.” Increased DNAPL removal can be attained using surfactants to mobilize and/or solubilize the pollutants. However, very little is understood of the methods developed by petroleum engineers beginning in the 1960s to overcome by‐passed, low‐permeability zones in heterogeneous oil reservoirs. By injecting or causing the formation of viscous fluids in the subsurface, petroleum engineers caused increased in‐situ pressures that forced fluid flow into low permeability units as well as the higher permeability thief zones. Polymer flooding involves injecting a viscous aqueous polymer solution into the contaminated aquifer. Foam flooding involves injecting surfactant to decontaminate the high‐permeability zones and then periodic pulses of air to cause a temporary viscous foam to form in the high‐permeable zones after all DNAPL is removed. Later surfactant pulses are directed by the foam into unswept low‐permeable units. These methods have been applied to DNAPL removal using surfactants but they can also be applied to the injection of bio‐amendments into low‐permeability zones still requiring continued remediation. Here we discuss the principles of mobility control as practiced in an alluvial aquifer contaminated with chlorinated solvent and coal tar DNAPLs as well as some field results. © 2003 Wiley Periodicals, Inc.  相似文献   
950.
A fish‐consumption advisory is currently in effect in a seven‐mile stretch of the Grasse River in Massena, New York, due to elevated levels of PCBs in fish tissue. One remedial approach that is being evaluated to reduce the PCB levels in fish from the river is in situ capping. An in‐river pilot study was conducted in the summer of 2001 to assess the feasibility of capping PCB‐containing sediments of the river. The study consisted of the construction of a subaqueous cap in a seven‐acre portion of the river using various combinations of capping materials and placement techniques. Optimal results were achieved with a 1:1 sand/topsoil mix released from a clamshell bucket either just above or several feet below the water surface. A longer‐term monitoring program of the capped area commenced in 2002. Results of this monitoring indicated: 1) the in‐place cap has remained intact since installation; 2) no evidence of PCB migration into and through the cap; 3) groundwater advection through the cap is not an important PCB transport mechanism; and 4) macroinvertebrate colonization of the in‐place cap is continuing. Additional follow‐up monitoring in the spring of 2003 indicated that a significant portion of the cap and, in some cases, the underlying sediments had been disturbed in the period following the conclusion of the 2002 monitoring work. An analysis of river conditions in the spring of 2003 indicated that a significant ice jam had formed in the river directly over the capping pilot study area, and that the resulting increase in river velocities and turbulence in the area resulted in the movement of both cap materials and the underlying sediments. The pilot cap was not designed to address ice jam–related forces on the cap, as the occurrence of ice jams in this section of the river had not been known prior to the observations conducted in the spring of 2003. These findings will preclude implementation of the longer‐term monitoring program that had been envisioned for the pilot study. The data collected immediately after cap construction in 2001 and through the first year of monitoring in 2002 serve as the basis for the conclusions presented in this article. It should be recognized that, based on the observation made in the spring of 2003, some of these conclusions are no longer valid for the pilot study area.The occurrence of ice jams in the lower Grasse River and their importance on sediments and PCBs within the system are currently under investigation. © 2003 Wiley Periodicals, Inc.  相似文献   
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