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   107篇
  免费   4篇
  国内免费   2篇
安全科学   2篇
环保管理   16篇
综合类   47篇
基础理论   7篇
污染及防治   1篇
评价与监测   1篇
社会与环境   34篇
灾害及防治   5篇
  2022年   4篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   5篇
  2015年   9篇
  2014年   1篇
  2013年   3篇
  2012年   3篇
  2011年   8篇
  2009年   4篇
  2008年   6篇
  2007年   10篇
  2006年   3篇
  2005年   5篇
  2004年   5篇
  2003年   1篇
  2002年   6篇
  2001年   1篇
  2000年   2篇
  1999年   11篇
  1998年   2篇
  1997年   2篇
  1995年   1篇
  1994年   1篇
  1992年   7篇
  1990年   1篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
排序方式: 共有113条查询结果,搜索用时 343 毫秒
71.
本文简要地分析了环境教育难于深入开展的原因,介绍了成功的教育方法--集中实施法,指出借鉴STS思想,在中学理科教改中来实施环境教育是今后的方向。  相似文献   
72.
Saudi Arabia has undergone revolutionary change to its economy since 1973, followed more recently by serious economic problems. The largely peripheral effects of urban planning upon the transformation of Jeddah from medieval town to international city are considered. The main urban problems and opportunities facing the city are identified, and the paper concludes with a question against the relevance of ‘Western’ notions of planning to another culture undergoing dynamic urban change.  相似文献   
73.
介绍了当前应用于中小型燃煤锅炉湿法除尘废水的各种中和处理技术,提出将除尘废水与中和处理与烟气脱硫结合进行的新工艺,为中小型锅炉烟气湿法脱硫除尘和废水循环回用处理提供了依据。  相似文献   
74.
Objectives: Studies from different parts of the world have indicated that the impact of road traffic incidents disproportionally affects young adults. Few known studies have been forthcoming from Arabian Gulf countries. Within Oman, a high proportion of the population is under the age of 20. Coupled with the drastic increase in motorization in recent years, there is a need to understand the state of road safety among young people in Oman. The current research aimed to explore the prevalence and characteristics of road traffic injuries among young drivers aged 17–25 years.

Methods: Crash data from 2009 to 2011 were extracted from the Directorate General of Traffic, Royal Oman Police (ROP) database in Oman. The data were analyzed to explore the impact of road crashes on young people (17–25 years), the characteristics of young driver crashes, and how these differ from older drivers and to identify key predictors of fatalities in young driver crashes.

Results: Overall, young people were overrepresented in injuries and fatalities within the sample time period. Though it is true that many young people in crashes were driving at the time, it was also evident that young people were often victims in a crash caused by someone else. Thus, to reduce the impact of road crashes on young people, there is a need to generally address road safety within Oman. When young drivers were involved in crashes they were predominantly male. The types of crashes these drivers have can be broadly attributed to risk taking and inexperience. Speeding and nighttime driving were the key risk factors for fatalities.

Conclusion: The results highlight the need to address young driver safety in Oman. From these findings, the introduction of a graduated driver licensing system with nighttime driving restrictions could significantly improve young driver safety.  相似文献   

75.
The Middle Mississippi River (MMR) and lower Missouri River (MOR) provide critical navigation waterways, ecological habitat, and flood conveyance. They are also directly linked to processes affecting geomorphic and ecological conditions in the lower MR and Delta. For this study, a method was developed to measure suspended‐sediment concentration (SSC) and turbidity along the MMR and the lower MOR using Landsat imagery. Data from nine United States Geological Survey water‐quality monitoring stations were used to create a model‐development dataset and a model‐validation dataset. Concurrent gaging data were identified for available Landsat images to generate the datasets. Surface‐reflectance filters were developed to eliminate images with cirrus cloud coverage or vessel traffic. Using the filtered model‐development dataset, unique reflectance‐SSC and reflectance‐turbidity models were developed for three Landsat sensors: Landsat 8 Operational Land Imager, Landsat 7 Enhanced Thematic Mapper Plus, and Landsat 4–5 Thematic Mapper. Coefficient of determination values for the models ranged from 0.72 to 0.88 for the model‐development dataset. The model‐validation dataset was used to evaluate the performance of the models and had coefficient of determination values ranging from 0.62 to 0.79.  相似文献   
76.
The presence of salt-excreting glands in extinct marine sauropsids has been long suspected based on skull morphology. Previously, we described for the first time the natural casts of salt-excreting glands in the head of the Jurassic metriorhynchid crocodyliform Geosaurus araucanensis from the Tithonian of the Vaca Muerta Formation in the Neuquén Basin (Argentina). In the present study, salt-excreting glands are identified in three new individuals (adult, a sub-adult and a juvenile) referable to the same species. New material provides significant information on the salt glands form and function and permit integration of evolutionary scenarios proposed on a physiological basis in extant taxa with evidence from the fossil record. G. araucanensis represents an advanced stage of the basic physiological model to marine adaptations in reptiles. G. araucanensis salt glands were hypertrophied. On this basis, it can be hypothesized that these glands had a high excretory capability. This stage implies that G. araucanensis (like extant pelagic reptiles, e.g. cheloniids) could have maintained constant plasma osmolality even when seawater or osmoconforming prey were ingested. A gradual model of marine adaptation in crocodyliforms based on physiology (freshwater to coastal/estuarine to estuarine /marine to pelagic life) is congruent with the phylogeny of crocodyliforms based on skeletal morphology. The fossil record suggests that the stage of marine pelagic adaptation was achieved by the Early Middle Jurassic. Salt gland size in the juvenile suggests that juveniles were, like adults, pelagic.  相似文献   
77.
在辽西上侏罗统义县组下部陆相湖泊沉积火山凝灰质泥页岩中保存的圣贤孔子鸟(Confuciusornis sanctus)带羽毛的骨架化石,展现了鸟类演化早期阶段的性别差异(即,性二态)特点.研究结果显示,这种生存于约140Ma前如鸡大小的古鸟类已与现代许多鸟类一样,雌雄个体差异不仅明显反映在羽衣和骨相上,而且还可能表现在行为上.  相似文献   
78.
对骑田岭岩体主体仰天湖单元粗中粒斑状角闪石黑云母二长花岗岩进行了黑云母40Ar-39Ar年龄测定,获得坪年龄为(155.1±1.8)Ma,等时线年龄为(154.7±1.8)Ma.该年龄样品提高了骑田岭岩体形成时代的面上控制程度,与前人有关高精度年代资料一起说明骑田岭序列为中侏罗世末-晚侏罗世初形成的大岩基,基本排除其内部有其它时代成分的可能.结合骑田岭地区锡矿与花岗岩的关系,认为江口一带具有寻找锡矿的前景.  相似文献   
79.
江西长江防洪干堤修筑在九江-黄梅平原第上系冲积层之上。作者通过对长江沿岸(江西段南岸)环境地质调查,依据大量的钻探工程资料,基本查明了防洪干堤基础工程地质条件,并对于堤形成水患灾害的类型、分布特征和致灾机制进行了综合分析,从而为今后防洪减灾提供了基础性地质依据。  相似文献   
80.
根据1984年9月至1990年2月对全市具有一定代表性的10余所中学的噪声和大气环境质量调查结果,分别作出初步评价,并提出若干防治措施和建议。  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