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   91212篇
  免费   1224篇
  国内免费   1094篇
安全科学   3725篇
废物处理   3374篇
环保管理   13864篇
综合类   21276篇
基础理论   26266篇
环境理论   72篇
污染及防治   14927篇
评价与监测   5517篇
社会与环境   3988篇
灾害及防治   521篇
  2022年   822篇
  2021年   812篇
  2020年   648篇
  2019年   872篇
  2018年   1148篇
  2017年   1196篇
  2016年   2191篇
  2015年   1840篇
  2014年   2593篇
  2013年   9264篇
  2012年   2183篇
  2011年   2447篇
  2010年   3280篇
  2009年   3431篇
  2008年   2038篇
  2007年   1902篇
  2006年   2291篇
  2005年   2309篇
  2004年   2582篇
  2003年   2453篇
  2002年   1990篇
  2001年   2335篇
  2000年   1996篇
  1999年   1519篇
  1998年   1370篇
  1997年   1363篇
  1996年   1484篇
  1995年   1577篇
  1994年   1488篇
  1993年   1328篇
  1992年   1313篇
  1991年   1293篇
  1990年   1247篇
  1989年   1203篇
  1988年   1049篇
  1987年   984篇
  1986年   991篇
  1985年   1059篇
  1984年   1162篇
  1983年   1170篇
  1982年   1173篇
  1981年   1096篇
  1980年   946篇
  1979年   924篇
  1978年   824篇
  1977年   720篇
  1976年   641篇
  1974年   611篇
  1973年   637篇
  1972年   634篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
   Global change, i.e. the mega-process radically transforming the relationship between nature and human civilization since the end of World War II, is investigated from the point of view of systems analysis. It is argued that this unbridled process should rather be domesticated by planetary control strategies transpiring from a new science called “geocybernetics”. The formal aspects of geocybernetic theory are sketched and illustrated in a tutorial theatre world reflecting the overall environment and development problematic. Within this setting a straightforward operationalization of the sweeping “sustainable development” ideal through a set of concise paradigms can be achieved. Evidence is provided that geocybernetics is actually feasible on the basis of earth system modelling and fuzzy-control techniques.  相似文献   
103.
104.
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   
105.
106.
107.
108.
109.
The effects of food availability, female size, and social interactions on the quality of Pomacentrus amboinensis larvae at hatching were examined using two field-based experiments. In Experiment 1, food availability and female size significantly influenced size, eye diameter and levels of yolk reserves of larvae at hatching. Small females (47 to 52 mm standard length, SL) whose diets were not supplemented, produced the longest larvae (3.0 ± 0.01 mm total length, TL) with the least yolk reserves (50.1 ± 1.04 μm2). Irrespective of female size, those that received additional food produced larvae with the largest yolk-sacs (large females: 87.60 ± 1.53 μm2; small females: 80.14 ± 1.24 μm2). In Experiment 2, interactions with conspecifics had a greater affect on the somatic development of larvae at hatching than food availability. Increased social interactions resulted in larvae that were ⋍3% longer, with 2% greater head depth, than larvae from females that spawned in isolation on the experimental reefs. Fed females produced larvae with ⋍20% more yolk than larvae from females whose diets were not supplemented. All three factors (food availability, female size, and intensity of social interactions) tested within these experiments vary spatially and temporally among reefs. There is the potential, therefore, for larvae at the onset of the planktonic stage to vary in quality, level of development, and probability of survival. Received: 12 August 1996 / Accepted: 26 August 1996  相似文献   
110.
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