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   519篇
  免费   5篇
  国内免费   7篇
安全科学   9篇
废物处理   18篇
环保管理   83篇
综合类   50篇
基础理论   141篇
污染及防治   152篇
评价与监测   46篇
社会与环境   27篇
灾害及防治   5篇
  2023年   5篇
  2022年   10篇
  2021年   16篇
  2020年   13篇
  2019年   10篇
  2018年   15篇
  2017年   17篇
  2016年   23篇
  2015年   20篇
  2014年   20篇
  2013年   47篇
  2012年   24篇
  2011年   42篇
  2010年   19篇
  2009年   22篇
  2008年   32篇
  2007年   38篇
  2006年   22篇
  2005年   20篇
  2004年   14篇
  2003年   17篇
  2002年   10篇
  2001年   7篇
  2000年   6篇
  1999年   5篇
  1998年   4篇
  1997年   3篇
  1996年   6篇
  1995年   1篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1988年   3篇
  1987年   3篇
  1986年   1篇
  1984年   2篇
  1983年   2篇
  1982年   3篇
  1981年   6篇
  1980年   1篇
  1976年   3篇
  1975年   1篇
  1974年   1篇
  1968年   1篇
  1967年   2篇
排序方式: 共有531条查询结果,搜索用时 15 毫秒
61.
62.
63.

Rodent outbreaks affect many farmland areas worldwide and the negative environmental impacts of control campaigns cause intense social tensions. In such conservation conflicts, understanding stakeholders’ viewpoints is critical to promote ecologically sustainable management. We used Q-methodology, a framework standing between qualitative and quantitative social research, to investigate human subjectivity and understand conflicts caused by rodent outbreaks in Spain. We interviewed farmers, conservationists, hunters, and governmental agencies, and identified five main discourses about the origins and consequences of the conflictive situation. Finding sustainable management is impaired by opposing views about causes and consequences of vole outbreaks and their management, which are at the root of the conflict. Social tensions will likely remain until the underlying conflicts between people holding different views are also managed. Decision-making should therefore focus on mitigating underlying conflicts. Using trained independent mediators would help the effective resolution of conservation conflicts caused by rodent outbreaks and their management.

  相似文献   
64.
65.
66.
Egg data from ichthyoplankton monitoring sites in the western English Channel (1988–2003) and northern Spain (1990–2000) and macroscopic maturity data from biological samples of purse seine landings in western and southern Iberia (1980–2004) are used to describe the spawning seasonality of sardine (Sardina pilchardus) in European waters of the northeast Atlantic using generalised additive models. The fitted models reveal a double peak in spawning activity during early summer and autumn in the western Channel, a wider spring peak off northern Spain and a broad winter season in the western and southern Iberian Peninsula. At all sites, a high probability of spawning activity was observed over at least 3 months of the year, with the duration of the season increasing with both decreasing latitude and increasing fish size. Off western and southern Iberia there are indications that the spawning season has been of longer duration in recent years for all size classes (reaching in some cases 8 months of the year for large fish). These patterns are in general agreement with existing literature and theoretical expectations of sardine spawning being driven locally by the seasonal cycle of water temperature, assuming preferences for spawning at 14 –15°C and avoidance for temperatures below 12°C and above 16°C. Regional quotient plots indicated that spawning tolerance to higher temperatures increases progressively with decreasing latitude. Despite the weak evidence for geographical differences in temperature tolerance that may have some genetic origin, the degree of spatio-temporal overlap in sardine-spawning activity within Atlantic European waters is unlikely to promote any reproductive isolation in that area.  相似文献   
67.
Randomly amplified polymorphic DNA (RAPD) banding patterns were compared between samples of the netted dogwhelk Nassarius reticulatus from 11 locations along the NW Iberian Peninsula coast. To detect if rias (estuaries formed by drowned river valleys) might promote genetic differentiation, five sampling sites were located within a ria (ria of Muros) and the remaining six were scattered along open-coast areas at increasing distances from the ria mouth. Population differentiation statistics (Φ-values) were estimated using a hierarchical analysis of molecular variance (AMOVA) with samples sorted into two groups: open-coast and ria populations. Despite a high potential to disperse, AMOVA demonstrated a modest, statistically significant genetic heterogeneity among N. reticulatus populations. Most of the genetic structure resided in differences among open-coast populations; ria populations were genetically homogeneous. No obvious geographical pattern was detected for the pairwise genetic distances (non-metric multidimensional scaling; UPGMA tree; Mantel test). Unlike previous studies with other species at a variety of estuarine systems other than rias, there was no evidence that the ria of Muros may enhance the genetic divergence of N. reticulatus populations. This discrepancy is discussed in relation to the biological features of the species (high dispersal potential and a preference for mid-low estuarine habitat) and the strong hydrographic connectivity between ria and neighbouring off-shore waters.  相似文献   
68.
最近几年,位于马西南部的里奥格兰德联合大学的研究生土木工程项目开展了一些与建筑环境的可持续性有关的活动.其中一些活动与教育有关,一些活动与设计和建造有关.本文介绍了应用可持续性原则的项目的总体概念框架及其主要总体目标.新近的一个项目(对一所技术学校的提议)说明了如休在一个具体的项目处理框架及其目标问题1.文章也简要介绍了其他研究和设计活动.并简单讨论了把可持续性问题纳入发发中国家的土地利用规划以及项目设计的障碍.  相似文献   
69.
The bulk magnetic susceptibility of sediments from artificial and natural lakes around a large coal-fired power station in NE Spain has been measured. Higher magnetic susceptibility values are found in lake sediments located SE of the power station. This distribution of susceptibility values is compatible with environmental and meterological studies of emissions from the power station, which indicate a dominant SE plume direction. Mineralogical studies, by means of X-ray diffraction and scanning electron microscopy, show that the highest susceptibility values found in the sediments are caused by magnetic iron spinels in the fly ash that is transferred to the environment by the power station particulate emissions. After the quantitative mineralogical studies of fly ash, two different methods of fly ash content determination in the sediments have been devised, showing very similar results. The low background magnetic susceptibility of the sediments in the study area and the high susceptibility resulting from the input of magnetic fly ash particles allows both delimitation of the polluted area around the power station, and quantification of the fly ash input into the natural sediments.  相似文献   
70.
Twenty-one species of halocyprid ostracods were identified from 7778 specimens caught in 144 neuston net hauls taken from the research vessel “Walther Herwig” in the Atlantic Ocean. Hauls taken during dusk were richer both in specimens and in species than later in the night. Few if any specimens occurred in daytime catches. Eighty-eight percent of the specimens were male Conchoecia spinirostris, which were observed to swarm at the surface at dusk in two positions. Many of the species occurred over a wide range of hydrographic conditions, and only in the region 40°S; 39°W did representatives of the cold-water fauna appear. The species could be categorised into 5 groups, depending on zoogeographical ranges and daytime depth distributions; the majority of the species ranged from 40°N–40°S, and had daytime maxima in the upper 100 m. It is concluded that ostracods only constitute important food items for carnivores feeding in the neuston when the latter are permanently in the neuston; the occurrence of vertically migrating carnivores does not coincide with the maximum occurrence of ostracods in the neuston.  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