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   275篇
  免费   3篇
  国内免费   6篇
安全科学   3篇
废物处理   10篇
环保管理   22篇
综合类   50篇
基础理论   66篇
污染及防治   84篇
评价与监测   17篇
社会与环境   31篇
灾害及防治   1篇
  2023年   3篇
  2022年   7篇
  2021年   2篇
  2020年   5篇
  2019年   13篇
  2018年   8篇
  2017年   16篇
  2016年   12篇
  2015年   8篇
  2014年   16篇
  2013年   12篇
  2012年   18篇
  2011年   16篇
  2010年   17篇
  2009年   15篇
  2008年   15篇
  2007年   26篇
  2006年   7篇
  2005年   10篇
  2004年   5篇
  2003年   11篇
  2002年   12篇
  2001年   6篇
  2000年   3篇
  1999年   5篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1990年   1篇
  1983年   1篇
  1964年   1篇
  1962年   1篇
  1956年   1篇
  1954年   1篇
排序方式: 共有284条查询结果,搜索用时 278 毫秒
181.
Regional Environmental Change - This paper synthesizes what is known about the physical and biophysical impacts of climate change and their consequences for societies and development under...  相似文献   
182.
The microhabitat of Symbion pandora (Cycliophora) was described by recording the prevalence and distribution of two life cycle stages, namely feeding individuals and chordoid cysts on the mouth appendages of 65 Norway lobsters. The commensals infested lobsters with a carapace length >35 mm, while the intensity of the commensals increased with host size up to more than 1,100 feeding individuals and 173 chordoid cysts. Feeding individuals and chordoid cysts were found on all six pairs of mouth appendages, but were rare on Mxp3. A Kruskal–Wallis analysis of variance showed that the distribution of the two stages over individual segments deviated significantly from random expectations (P<0.001). Feeding individuals densely aggregated on a few medial segments, generally those that are pervaded by suspended food particles during host feeding. Chordoid cysts, which arise from non-feeding females occurred in low numbers and were more evenly distributed over the segments, often aggregating on the lateral parts and in the articulations of the segments. Based on these findings we suggest that the feeding activity of S. pandora is synchronized with that of the host.  相似文献   
183.
184.
马龙 《世界环境》2014,(2):46-48
谈起善于利用媒体的政客,德国前总理施罗德一定名列前茅.就在2002年德国大选数周前,面临连任的他在民调中仍然大幅落后.然而一场百年不遇的洪灾过后,施罗德赢得了国民以及以刁钻刻薄闻名的德国媒体的一片好评,最终在大选中成功实现大逆反.这一成功很大程度上取决于施罗德的危机公关处理能力.  相似文献   
185.
186.
Since the early 2000s routine fish surveys have recorded increasing numbers of snake pipefish, Entelurus aequoreus, in the northeast Atlantic. Fishermen and divers have also commented on this increase and pipefish have started to appear in the diet of seabirds and other marine predators. This paper collates information from these diverse sources and assesses the current status of snake pipefish. We found compelling evidence of a dramatic increase in the abundance of snake pipefish starting around 2003 and continuing up to the present (2006) and a range expansion northwards to Spitzbergen and the Barents Sea. Since 2004 snake pipefish have been increasingly recorded in the diet of many species of seabird breeding in colonies around the coast of the UK, and in Norway, Iceland and the Faeroe Islands. Information on the nutrient value of snake pipefish is currently lacking but their rigid, bony structure makes them difficult for young seabirds to swallow and there are numerous records of chicks choking to death. Thus, in the case of avian predators during the breeding season, it appears unlikely that increased abundance of snake pipefish will provide a useful alternative prey. The reason for the rapid and dramatic increase in numbers of snake pipefish is currently unclear but such events are characteristic of marine ecosystems and will almost certainly have an effect on food web dynamics.  相似文献   
187.
188.
A new modelling approach to urban sprawl dynamics is introduced which allows representing qualitative knowledge on relations between moving actor populations and properties of locations. The results of this Qualitative Attractiveness Migration (QuAM) Model are scenario-like sets of possible future developments of the urban system, much in contrast to quantitative forecasts gained by traditional modelling approaches. QuAM models allow for the interaction between internal dynamics and external influences. The application of the new approach is exemplified by the case of urban sprawl in Leipzig since 1990. It was possible to reproduce the observed qualitative development and to calculate future scenarios. The scenario runs project a new wave of middle class driven residential sprawl and suggest implications for sprawl reducing policy interventions.  相似文献   
189.

Behavioral studies of gynandromorphism, also called as sex mosaic, contribute to the understanding of the relationship between morphological gender and sexual identity of an animal. Few studies have focused on the behaviors of gynandromorphic spiders because of a scarcity of gynandromorphic individuals in the field. In this study, we collected a gynandromorphic spider, Myrmarachne formicaria (De Geer 1778) (Araneae: Salticidae), from the field and examined its morphology and sex-specific behavior in the laboratory. The right half of the gynandromorphic spider presented male characteristics and the left half female characteristics. It showed courtship behavior to M. formicaria females and agonistic behavior to the males. These results indicate that the gynandromorphic spider’s sexual identity is male. Our findings suggest that a spider can exhibit behaviors of male sexuality, although the external morphology has the characteristics of both sexes. To the best of our knowledge, this is the first report of a gynandromorphic individual and its behavior in the genus Myrmarachne.

  相似文献   
190.
Mitigation and Adaptation Strategies for Global Change - The assessment of greenhouse gases (GHGs) and air pollutants emitted to and removed from the atmosphere ranks high on international...  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