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   51873篇
  免费   1180篇
  国内免费   5694篇
安全科学   2063篇
废物处理   2544篇
环保管理   5876篇
综合类   15696篇
基础理论   12370篇
环境理论   13篇
污染及防治   13329篇
评价与监测   3149篇
社会与环境   2836篇
灾害及防治   871篇
  2023年   361篇
  2022年   995篇
  2021年   927篇
  2020年   731篇
  2019年   694篇
  2018年   1474篇
  2017年   1536篇
  2016年   1682篇
  2015年   1413篇
  2014年   2053篇
  2013年   3999篇
  2012年   2469篇
  2011年   3255篇
  2010年   2543篇
  2009年   2591篇
  2008年   2991篇
  2007年   3019篇
  2006年   2197篇
  2005年   1761篇
  2004年   1514篇
  2003年   1607篇
  2002年   1516篇
  2001年   1577篇
  2000年   1302篇
  1999年   914篇
  1998年   698篇
  1997年   743篇
  1996年   696篇
  1995年   694篇
  1994年   604篇
  1993年   520篇
  1992年   527篇
  1991年   473篇
  1990年   494篇
  1989年   411篇
  1988年   396篇
  1987年   336篇
  1986年   332篇
  1985年   308篇
  1984年   360篇
  1983年   318篇
  1982年   366篇
  1981年   319篇
  1980年   247篇
  1979年   279篇
  1978年   257篇
  1977年   219篇
  1974年   235篇
  1973年   220篇
  1972年   220篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
112.
本文通过对乡镇工业经济发展现状及其环境问题的评价分析,提出乡镇工业环境管理应按本地自然条件、经济发展水平和乡镇企业的特点,实施分区域、按行业、有重点地进行管理的防治战略。并建议我国环境管理在以城市和大工业为重点的同时,及早将乡镇工业污染防治工作放在战略高度加以重视,切实加强乡镇工业环境管理。  相似文献   
113.
114.
In a 1981 survey of 436 Florida citrus growers, 27 pesticide related poisoning incidents were reported that were to have taken place within one year of the interview date. From these reports it is possible to estimate that there are 376 citrus fieldworker related poisonings per year in Florida. This number of estimated poisonings may be developed into an incidence rate of 113 fieldworker poisonings per 10,000 fieldworkers.  相似文献   
115.
Living veligers of the Cassoidea have been observed to use a mantle appendage to form and resorb periostracum. Anatomical and histological examinations of a ranellid (Cymatium sp.) larva collected from the Red Sea in 1987 revealed the structure and location of the pallial appendage. The mantle edges of juvenile or adult species of the Cassoidea do not show a comparable specialization. It is demonstrated that cassoid larval conch characters are sufficient to prove the existence of a pallial appendage without anatomical confirmation. A mantle appendage is not known from teleplanic (long-living planktic) veligers of other gastropod superfamilies. In cases where the larval strategies of the latter are known they are totally different. Therefore it is suggested that the adaptation of cassoid larvae to pelagic life is unique among gastropods representing an autapomorphic character of the superfamily.  相似文献   
116.
This paper examines the relationship between survivor reactions to a downsizing and retention subsequent to a downsizing. We hypothesize that survivors who experience the downsizing as distributively, procedurally, and interactionally just and who see top management as trustworthy will feel more attached to the organization because each reduces the threat inherent in downsizing. In addition, we hypothesize that survivors who feel empowered will also feel more attached to the organization because they feel better able to cope with the downsizing. We further hypothesize that those survivors who feel more attached to the organization following the downsizing will be more likely to remain with the organization in the coming year. The theoretical model is tested on a sample of aerospace employees who survived an organizational downsizing. The trustworthiness of management, distributive justice, procedural justice, and three dimensions of empowerment are found to facilitate more organizational attachment. Higher levels of attachment are found, in turn, to facilitate less voluntary turnover in the year following the downsizing. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
117.
118.
119.
When combined in the lining and covering of waste-containment facilities, soil and geosynthetic components protect the environment by acting as a hydraulic barrier. Equipment loading may significantly increase the tensile stress induced in geosynthetic components, leading to a potential stability problem. Large equipment loadings may also result in a localized circular slip surface during construction operations. New analytical method based on discrete element modelling is proposed for estimating the distribution of tensile force developed in the individual geosynthetic components of the lining system and for evaluating the safety factor of slope failure due to equipment loading. The analytical results of an example are presented to demonstrate the applicability of the analytical method for the lining system of a waste landfill. The analyses of the example show that equipment loading provide a substantial increase in the tensile forces of the geosynthetic components of a lining system and that the possibility of shallow failure due to equipment loading increases as the slope becomes steeper. This method is a useful tool for analysing the lining system of waste landfills with complex lining components.  相似文献   
120.
Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii.  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