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   169篇
  免费   7篇
  国内免费   20篇
安全科学   17篇
环保管理   11篇
综合类   37篇
基础理论   74篇
污染及防治   9篇
评价与监测   6篇
社会与环境   14篇
灾害及防治   28篇
  2024年   1篇
  2023年   1篇
  2022年   3篇
  2021年   4篇
  2020年   5篇
  2019年   7篇
  2018年   4篇
  2017年   5篇
  2016年   13篇
  2015年   3篇
  2014年   2篇
  2013年   21篇
  2012年   6篇
  2011年   11篇
  2010年   17篇
  2009年   11篇
  2008年   7篇
  2007年   10篇
  2006年   12篇
  2005年   5篇
  2004年   11篇
  2003年   3篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1988年   1篇
  1982年   1篇
排序方式: 共有196条查询结果,搜索用时 15 毫秒
71.
论述了大气监测分析方法标准化研究的特点、内容、样品采集方法和保存条件,样品预处理方法和测定条件,干扰试验、方法的基本特征参数第一轮测定、实际样品的测定等问题。  相似文献   
72.
An analysis of the causes and circumstances of flood disaster deaths   总被引:4,自引:0,他引:4  
Jonkman SN  Kelman I 《Disasters》2005,29(1):75-97
The objective of this paper is to investigate and to improve understanding of the causes and circumstances of flood disaster deaths. A standardised method of classifying flood deaths is proposed and the difficulties associated with comparing and assessing existing information on flood deaths are discussed. Thirteen flood cases from Europe and the United States, resulting in 247 flood disaster fatalities, were analysed and taken as indicative of flood disaster deaths. Approximately two-thirds of the deaths occurred through drowning. Thus, a substantial number of flood disaster fatalities are not related to drowning. Furthermore, males are highly vulnerable to dying in floods and unnecessary risk-taking behaviour contributes significantly to flood disaster deaths. Based on these results, recommendations are made to prevent loss of life in floods. To provide a more solid basis for the formulation of prevention strategies, better systematic recording of flood fatalities is suggested, especially those caused by different types of floods in all countries.  相似文献   
73.
Females of many socially monogamous bird species commonly engage in extra-pair copulations. Assuming that extra-pair males are more attractive than the females’ social partners and that attractiveness has a heritable component, sex allocation theory predicts facultative overproduction of sons among extra-pair offspring (EPO) as sons benefit more than daughters from inheriting their father’s attractiveness traits. Here, we present a large-scale, three-year study on sex ratio variation in a passerine bird, the coal tit (Parus ater). Molecular sexing in combination with paternity analysis revealed no evidence for a male-bias in EPO sex ratios compared to their within-pair maternal half-siblings. Our main conclusion, therefore, is that facultative sex allocation to EPO is absent in the coal tit, in accordance with findings in several other species. Either there is no net selection for a deviation from random sex ratio variation (e.g. because extra-pair mating may serve goals different from striving for ‘attractiveness genes’) or evolutionary constraints preclude the evolution of precise maternal sex ratio adjustment. It is interesting to note that, however, we found broods without EPO as well as broods without mortality to be relatively female-biased compared to broods with EPO and mortality, respectively. We were unable to identify any environmental or parental variable to co-vary with brood sex ratios. There was no significant repeatability of sex ratios in consecutive broods of individual females that would hint at some idiosyncratic maternal sex ratio adjustment. Further research is needed to resolve the biological significance of the correlation between brood sex ratios and extra-pair paternity and mortality incidence, respectively.  相似文献   
74.
A major objective of analyzing multiple year tag return data in fisheries is to estimate fishing and natural mortality rates which may vary by age class and calendar year. To do this one needs to be able to estimate the reporting rates for the tags recovered. Some fisheries such as that for Southern Bluefin Tuna (Thunnus maccoyii) have multiple components with potentially different reporting rates for the tag returns. In this paper we develop a general model for multi-cohort, multi-year tag return analyses where there are multiple components to the fishery with potentially different reporting rates. We require the assumption that one component has a reporting rate of 100% (i.e., this could be the component of a boat based fishery where scientific observers are present). We show further how it is possible to partition the overall likelihood developed into two conditionally independent components. The first component of the likelihood is the standard multinomial likelihood that allows estimation of fishing and natural mortality rates. It uses the tag return matrix summed over all the components of the fishery. It requires an average reporting rate for the tag returns (where the average reporting rate is a weighted average of the individual reporting rates of the different components). The second component is also multinomial for the individual component tag returns and allows us to estimate individual component reporting rates. However, this requires that we augment our second component tag return likelihood with a catch data likelihood for the corresponding components. The methodology is illustrated on some Southern Bluefin Tuna tagging and catch data. We also discuss important model assumptions and give suggestions for future research including the integration of tag-return and catch at age data analyses.  相似文献   
75.
亚硒酸钠对蚯蚓的毒性及蚓体富硒作用的研究   总被引:7,自引:0,他引:7  
以100mgkg^-1,200mgkg^-1,300mg kg^-1等不同质量分数(w)的亚硒酸钠(NaSeO2)添加到蚯吲饵料中,研究了亚硒酸钠处理对蚯蚓生长发育及死亡的影响和蚯蚓的富硒作用,结果表明,3个w(NaSeO2)处理对蚯蚓生长发育和富硒量的影响都达到极显著水平,w(NaSeO2)越高,用其处理饲养的蚯蚓死亡率也较高,富硒量也较大,二者存在一定的正相关性,在200mg kg^-1的w(NaSeO2)处理下,当蚯蚓饲养到84d时,蚯蚓的富硒量可达到332.5mg kg^-1,同时死亡率高达90%。  相似文献   
76.
Data on individual tree mortality in relatively healthy (Berezinskiy biosphere reserve) and damaged (surroundings of the mineral fertilizer plant ‘Achema’) even-aged Scots pine (Pinus sylvestris L.) stands are presented. Tree size and competition intensity were found to be the most significant predictors of individual tree mortality in all age groups of the relatively healthy Scots pine stands, however, an essential reduction in the closeness of relations between the tree mortality rate and these variables was determined with the aging of stands. An exponential decrease in tree mortality probability with an increase of tree size is characteristic for trees suffering different competition intensity, however, this decrease becomes much more pronounced as the competition pressure increases. The relations of different tree and stand variables with tree mortality probability have been found to become much weaker in the polluted environment. An exponential increase in tree mortality probability with an increase of crown defoliation was characteristic of damaged Scots pine stands, however, the rate of the increase was different in different age and diameter classes. The impact of crown defoliation on tree mortality rate increased with the aging of stands. At the same defoliation level, individual tree mortality probability was much higher for smaller suppressed trees, however, a relative increase in tree mortality probability along with an increase of crown defoliation was more pronounced for dominant trees. Conclusion: a higher mortality of damaged (defoliated) trees should be considered while assessing losses in forest productivity in a polluted environment.  相似文献   
77.
Background: In 2011, about 30,000 people died in motor vehicle collisions (MVCs) in the United States. We sought to evaluate the causes of prehospital deaths related to MVCs and to assess whether these deaths were potentially preventable.

Methods: Miami–Dade Medical Examiner records for 2011 were reviewed for all prehospital deaths of occupants of 4-wheeled motor vehicle collisions. Injuries were categorized by affected organ and anatomic location of the body. Cases were reviewed by a panel of 2 trauma surgeons to determine cause of death and whether the death was potentially preventable. Time to death and hospital arrival times were determined using the Fatality Analysis Reporting System (FARS) data from 2002 to 2012, which allowed comparison of our local data to national prevalence estimates.

Results: Local data revealed that 39% of the 98 deaths reviewed were potentially preventable (PPD). Significantly more patients with PPD had neurotrauma as a cause of death compared to those with a nonpreventable death (NPD) (44.7% vs. 25.0%, P =.049). NPDs were significantly more likely to have combined neurotrauma and hemorrhage as cause of death compared to PPDs (45.0% vs. 10.5%, P <.001). NPDs were significantly more likely to have injuries to the chest, pelvis, or spine. NPDs also had significantly more injuries to the following organ systems: lung, cardiac, and vascular chest (all P <.05). In the nationally representative FARS data from 2002 to 2012, 30% of deaths occurred on scene and another 32% occurred within 1 h of injury. When comparing the 2011 FARS data for Miami–Dade to the remainder of the United States in that year, percentage of deaths when reported on scene (25 vs. 23%, respectively) and within 1 h of injury (35 vs. 32%, respectively) were similar.

Conclusions: Nationally, FARS data demonstrated that two thirds of all MVC deaths occurred within 1 h of injury. Over a third of prehospital MVC deaths were potentially preventable in our local sample. By examining injury patterns in PPDs, targeted intervention may be initiated.  相似文献   

78.
我国臭氧短期暴露与人群死亡风险的Meta分析   总被引:4,自引:0,他引:4  
为评价中国臭氧短期暴露对人群死亡率的影响,获取臭氧污染与人群死亡的暴露-反应关系.检索了Pub Med、SCI(Science Ciation Index)、Ebsco、Ovid、中国生物医学文献数据库、维普中文科技期刊全文数据库、万方数据库和中国知网等,检索时间均为1990年1月1日至2014年12月31日,以"O3or ozone"、"mortality"、"China"、"臭氧"及"死亡"为关键词查找关于臭氧短期暴露对人群死亡率影响的文献.依据文献纳入和排除标准,进行文献筛选和质量评价.纳入文献后分别提取臭氧的暴露反应关系,采用Stata12.0软件进行Meta分析,根据异质性结果选择相应的效应模型合并效应值,并对结果进行敏感性分析、发表偏倚检验与校正.结果显示,大气中臭氧浓度每增加10μg·m-3,人群非意外总死亡率、心血管系统疾病和呼吸系统疾病死亡率分别增加0.40%(95%可信限(CI):0.303%~0.498%)、0.448%(95%CI:0.171%~0.724%)和0.461%(95%CI:0.225%~0.697%).与国外其它未纳入中国研究文献的Meta分析结果进行比较发现,中国的臭氧短期暴露对死亡风险影响的暴露-反应关系系数较高.大气中臭氧浓度的上升会导致我国人群非意外总死亡率、心血管系统疾病死亡率和呼吸系统疾病死亡率的增加.  相似文献   
79.
Urban forest ecosystems are complex and vulnerable social–ecological systems. The relationship between urban forests and housing is particularly variable and uncertain. We examine the influence of building renovation and rental housing on public trees at the parcel and street-section scale in a residential neighbourhood in Toronto, Canada. We use empirical data describing multiple tree inventories and government open data describing building permit applications to test for effects on urban forest structure, tree mortality, and tree planting. We found that the presence and number of building permits significantly predicted mortality at both scales, while planting was positively correlated with building permits at the street-section scale only. Multi-unit parcels had significantly lower rates of planting than single-unit parcels and multi-unit housing was positively correlated with mortality at the street-section scale. These findings suggest that where concentrated changes in housing stock are occurring, substantial losses of trees and associated ecosystem services are possible.  相似文献   
80.
Mortality of animals on roads is a critical threat to many wildlife populations and is poised to increase strongly because of ongoing and planned road construction. If these new roads cannot be avoided, effective mitigation measures will be necessary to stop biodiversity decline. Fencing along roads effectively reduces roadkill and is often used in combination with wildlife passages. Because fencing the entire road is not always possible due to financial constraints, high-frequency roadkill areas are often identified to inform the placement of fencing. We devised an adaptive fence-implementation plan to prioritize road sections for fencing. In this framework, areas along roads of high, moderate, and low levels of animal mortality (respectively, roadkill hotspots, warmspots, and coldspots) are identified at multiple scales (i.e., in circles of different diameters [200–2000 m] in which mortality frequency is measured). Fence deployment is based on the relationship between the amount of fencing being added to the road, starting with the strongest roadkill hotspots, and potential reduction in road mortality (displayed in mortality-reduction graphs). We applied our approach to empirical and simulated spatial patterns of wildlife–vehicle collisions. The scale used for analysis affected the number and spatial extent of roadkill hot-, warm-, and coldspots. At fine scales (e.g., 200 m), more hotspots were identified than at coarse scales (e.g., 2000 m), but combined the fine-scale hotspots covered less road and less fencing was needed to reduce road mortality. However, many short fences may be less effective in practice due to a fence-end effect (i.e., animals moving around the fence more easily), resulting in a trade-off between few long and many short fences, which we call the FLOMS (few-long-or-many-short) fences trade-off. Thresholds in the mortality-reduction graphs occurred for some roadkill patterns, but not for others. Thresholds may be useful to consider when determining road-mitigation targets. The existence of thresholds at multiple scales and the FLOMS trade-off have important implications for biodiversity conservation.  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