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   45篇
  免费   5篇
  国内免费   3篇
安全科学   7篇
环保管理   7篇
综合类   19篇
基础理论   6篇
污染及防治   3篇
评价与监测   8篇
灾害及防治   3篇
  2021年   1篇
  2020年   3篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   2篇
  2014年   1篇
  2013年   1篇
  2012年   2篇
  2011年   5篇
  2010年   3篇
  2009年   3篇
  2007年   2篇
  2006年   3篇
  2005年   1篇
  2003年   4篇
  2002年   1篇
  2001年   3篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1977年   1篇
排序方式: 共有53条查询结果,搜索用时 171 毫秒
21.
基于遥感影像、无人机航摄与移动核查技术,构建了集自然保护区"一张图"、图斑任务管理、移动核查为一体的天地一体化自然保护区人类活动监管系统,并以防城金花茶国家级自然保护区为例,进行试点监测监管研究。结果表明,利用监管系统可提高自然保护区监管时效性,有效解决监管盲区。对防城金花茶国家级自然保护区的人类活动进行监测评价,该保护区有工矿用地、农田、居民点、道路、其他人工设施等5类,以农田、居民点、普通道路为主,人类活动影响一般。  相似文献   
22.
23.
冯树常  熊华南 《灾害学》1999,14(3):7-11
针对防治法-水利工程防洪法的缺点,提出一个全新的防洪思路-气象工程防洪法,通过从源头控制引起洪涝灾害的水源-降水的时空分布,达到控制水患灾害和充分合理利用水资源的目的,既可减少灾损,节省用于防洪的大量人力物力财力。  相似文献   
24.
华北地区城市绿地固碳能力测算研究   总被引:1,自引:0,他引:1  
文章通过对位于华北地区的7个案例的城市绿地植被固碳能力的研究,形成一套系统的计算方法.结果表明:适用于雄安新区的城市绿地单位面积固碳能力约为2.62 kg/a m2;各个植被群落的固碳能力从大到小依次为乔木(2.66kg/am2)、灌木(2.59kg/a·m2)、地被(2.01 kg/a·m2).研究结果将为实现城市绿...  相似文献   
25.
根据2007年原国家环境保护总局空气质量日报86个城市的空气污染指数资料,分析我国城市大气污染的时空分布特征。结果表明,我国城市大气污染时空分布特征明显,大气污染冬季最严重,其次为春秋季节,夏季最好;污染总体上北方重于南方。城市大气污染由人类活动及当地特殊的地理位置综合影响形成,沙尘天气加重了北方大气污染。  相似文献   
26.
Diesel vehicles are responsible for most of the traffic-related nitrogen oxide (NOx) emissions, including nitric oxide (NO) and nitrogen dioxide (NO2). The use of after-treatment devices increases the risk of high NO2/NOx emissions from diesel engines. In order to investigate the factors influencing NO2/NOx emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter (CDPF). NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NOx ratios downstream of the CDPF range around 20%–83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NOx emissions. The maximum NO2/NOx emission appears at the exhaust temperature of 350°C. The space velocity, engine-out PM/NOx ratio (mass based) and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NOx emissions decreased with increasing space velocity and engine-out PM/NOx ratio. When the CO conversion ratios range from 80% to 90%, the NO2/NOx emissions remain at a high level.  相似文献   
27.
利用2008年和2009年南太湖蓝藻监测数据,分析研究主要入湖口的蓝藻水华时空分布规律,寻找与蓝藻生长密切相关的响应因子并将其作为蓝藻预警指示指标,为环保部门制定蓝藻应急监测预案、提高蓝藻预警预测的准确性提供科学参考。  相似文献   
28.
依据美国国家航空和宇航局(NASA)于2010年4月发布的《基于风险响应的决策方法技术手册》,介绍了NASA采用的基于风险响应的决策方法(RIDM),分析了RIDM风险管理策略的产生背景、运作情况、适用范围、主要特点和成功做法,并对国内开展航天工程项目的风险量化评估以及进行相应领域的风险管理研究提出了若干启示。  相似文献   
29.
Residents of mating territories interact with different categories of conspecifics: females, nonneighbor males, and neighbor males. Interaction with these different types of conspecifics is likely to have different costs and benefits; for example, interactions with females will be beneficial, while interactions with neighbors are more likely to be costly. In this study, we investigated patterns of intrusions and space use in territorial male amberwing dragonflies (Perithemis tenera) to test the idea that residents will adjust their use of space to maximize their beneficial interactions with conspecifics while minimizing their costly interactions with conspecifics. Because territories were arranged linearly around the edge of a pond, each resident had two neighbors, one of which was often closer to the focal resident than the other. Residents experienced more intrusions by neighbors and fewer intrusions by females on the side of their closer neighbor. Residents generally perched on the side of their territory that experienced the fewest intrusions by neighbors and the most intrusions by females, but the pattern was more strongly related to neighbor intrusions than female intrusions. Subsequent to pursuits of neighbors and females, residents tended to shift their perches away from where they pursued neighbors but toward where they pursued females. Nonneighbor intrusions were not affected by neighbor proximity, nor did residents adjust their space use in response to nonneighbor intrusions. Our results suggest that residents do adjust their space use in response to intrusions by conspecifics, that their adjustment depends on the type of conspecific that intruded, and that residents may be using a simple decision rule such as "move away from male intrusions, move closer to female intrusions" to adjust their within-territory space use.Communicated by D. Gwynne  相似文献   
30.
This paper demonstrates that while pattern formation can stabilize individual-based models of predator–prey systems, the same individual-based models also allow for stabilization by alternate mechanisms, particularly localized consumption or diffusion limitation. The movement rules of the simulation are the critical feature which determines which of these mechanisms stabilizes any particular predator–prey individual-based model. In particular, systems from well-connected subpopulations, in each of which a predator can attack any prey, generally exhibit stabilization by pattern formation. In contrast, when restricted movement within a (sub-)population limits the ability of predators to consume prey, localized consumption or diffusion limitation can stabilize the system. Thus while the conclusions from differential equations on the role of pattern formation for stability may apply to discrete and noisy systems, it will take a detailed understanding of movement and scales of interaction to examine the role of pattern formation in real systems. Additionally, it will be important to link an understanding of both foraging and inter-patch movement, since by analogy to the models, both would be critical for understanding how real systems are stabilized by being discrete and spatial.  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