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   143篇
  免费   20篇
  国内免费   45篇
安全科学   8篇
环保管理   25篇
综合类   117篇
基础理论   18篇
污染及防治   2篇
评价与监测   4篇
社会与环境   23篇
灾害及防治   11篇
  2023年   5篇
  2022年   9篇
  2021年   8篇
  2020年   13篇
  2019年   5篇
  2018年   13篇
  2017年   6篇
  2016年   12篇
  2015年   15篇
  2014年   7篇
  2013年   12篇
  2012年   16篇
  2011年   11篇
  2010年   13篇
  2009年   9篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   4篇
  2004年   3篇
  2003年   3篇
  2002年   4篇
  2001年   3篇
  2000年   3篇
  1999年   4篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
排序方式: 共有208条查询结果,搜索用时 31 毫秒
141.
随着昌吉州经济的快速发展,特别是农业优势资源转换战略的实施,农副产品加工业已成为昌吉州经济增长的支柱产业之一,为提高昌吉州农业产值、增加农民收入做出了贡献。但在提升昌吉州经济实力的同时,也对环境造成了一定的负面影响。从昌吉州番茄企业现状和污染状况等方面对昌吉州番茄企业存在的环境问题及环保治理设施建设和运行的经济可行性进行分析,并就番茄企业生产对废水的综合治理提出了方法措施。  相似文献   
142.
西藏第二产业发展现状分析   总被引:1,自引:0,他引:1  
西藏解放以来,第二产业从无到有经历了曲折的发展历程,发展迅速,总产值比重不断提高,已形成以矿产资源开采加工为主的较为完备的产业体系.但无论与全国平均水平还是西部欠发达地区相比,西藏第二产业发展仍相对落后,表现在产值比重低、产业发展对地方经济拉动能力非常有限,产业链短,效率低,产业结构偏离度高,难以有效吸收当地劳动力就业等方面.同时企业规模偏小,工业集中化低,没有形成有效的产业集聚地.优先发展第二产业,产业结构调整,就业人口向第二产业转移仍是未来西藏产业结构调整的重要任务.本文重点分析西藏第二产业产值、结构和劳动生产率、种类和规模变化,探讨了西藏第二产韭发展现状,认为当前西藏第二产业发展中存在较大问题,主要表现在重工业比重大,民用工业发展滞后,工业可持续性不强等,基于上述问题,文章提出了加大投资力度、加强人才培养、优化产业结构、积极发展民营企业和提高工业集中度的对策建议.  相似文献   
143.
生态功能区划是实施区域生态环境保护、建设和科学管理的基础。以云南省生态功能区划方案为背景,利用遥感和GIS等先进的空间模拟技术,综合考虑自然因素与人为因素的影响,形成楚雄州生态功能区划方案,将楚雄州划分为2个一级生态区、9个二级生态亚区、17个三级生态功能区。在完成生态功能区划的基础上,根据人与自然相互关系的基本格局和宏观生态环境管理的需要,将不同类型的生态功能区进行统筹和归并,把楚雄州划分为农产品提供生态功能区、林产品提供生态功能区、生物多样性保护生态功能区、水土保持生态功能区、水源涵养生态功能区、城镇农业与居住生态功能区,并对各生态功能类型区进行了概述,阐明各区存在的主要生态问题和生态保护的主要方向。  相似文献   
144.
The main objective of this study is to simulate the potential vegetation types on the basis of environmental parameters.The paper took Barkam County in a mountainous region of the Eastern Tibetan Plateau as the study area.The vegetation distribution was mapped in 1994 and 2007 based on TM remote sensing images by object-oriented interpretation method.We overlaid the two maps to find out the vegetation patches which have not changed,and took them as stable types.Fifty per cent of the stable patches were randomly sampled to operate the logistic regression with related environmental parameters;others were used as test data of simulated results.Seven environmental parameters were mapped,including elevation,slope,aspect,surface curvature,solar radiation,temperature and precipitation,based on DEM data and meteorological site data by GIS technology.The relationship between the spatial distribution of vegetation and environmental variables were quantified by logistic regression.The distribution probabilities of each vegetation type were calculated.Finally,the spatial distribution of potential vegetation was simulated.This research can provide a scientific basis for vegetation restoration and ecological construction in this area.  相似文献   
145.
利用高分一号多光谱影像,提取高原上面积大于1 km2的湖泊,并结合两次全国湖泊调查数据集及气象资料,对1975年至2015年湖泊变化及其环境影响因素进行分析。研究结果表明:2015年青藏高原1 km2以上湖泊个数共计1210个,自1975年以来整体呈扩张趋势;雅鲁藏布江流域由于蒸发量的增大湖泊面积呈下降趋势;西藏内流区由于降水量的增加、蒸发量的减少和温度升高引起冰川融化,导致湖泊面积持续扩张。为青藏高原湖泊变化及对环境气候波动的响应等研究提供参考。  相似文献   
146.
Soil erosion has a critical effect on ecological security and socioeconomics, which may deteriorate ecosystem services and common human well-being. The revised universal soil loss equation (RUSLE) was applied to assess soil erosion from 1984 to 2013 in the Tibetan Plateau and analyzed the temporal and spatial variation of soil erosion intensity. Furthermore, the temporal and spatial variation rates of soil erosion were explored across different ecosystems. The results indicated that the annual soil erosion fuctuated in the Tibetan Plateau, the soil erosion intensity decreased from south to north, and the most serious soil erosion was mainly distributed in the southern Tibetan Plateau (Xigaze and Changdu regions, Lhasa, and north of the Shannan region). The soil erosion intensity was higher in shrub, alpine meadow, and sparse vegetation ecosystems. The highest soil erosion was found in alpine meadow (2.17 × 1010 t), followed by alpine grassland (1.59 × 1010 t) and sparse vegetation (1.30 × 1010 t) ecosystems. Meanwhile, although the most serious soil erosion intensity was found in the regions of 3 000-4 000 m altitude, the soil erosion was mainly observed in the regions of 4 000-5 000 m altitude. In the three most recent decades, annual soil erosion decreased at a rate of-1.78 × 108 t/a. Additionally, soil erosion mainly increased in south of the Qiangtang Plateau and in the periphery of the Qaidam basin. Decreased soil erosion was mainly found along the Hengduan Mountains, central Himalayas. Although the increased annual normalized difference vegetation index (NDVI) had positive effects for soil protection, changes in soil erosion was mainly controlled by the change of annual precipitation. Thus, the fragility of ecological systems and increased rainfall erosivity accounted for the obviously increased soil erosion in the alpine grassland ecosystem (1.19 × 10 t/a). However, increased ecosystem stability and decreased rainfall erosivity contributed to the decreased soil erosion in forest and shrub ecosystems, by-0.77 × 10 t/a and-1.65 × 10 t/a, respectively. The slightly decreased rainfall erosivity accounted for a decrease of soil erosion in the sparse vegetation ecosystem (-0.44 × 10 t/a). Meanwhile, soil erosion has decreased in the alpine meadow ecosystem over the past 30 years, which may owing to the relatively higher NDVI that neutralized the increase of rainfall erosivity to some extent. This study revealed serious soil erosion regions and ecosystems in the Tibetan Plateau and explored possible reasons for variations in soil erosion in different ecosystems, which may provide a scientific reference for soil erosion conservation and control in the near future. © 2018 Science Press. All rights reserved.  相似文献   
147.
日本新潟县中越大地震震害调查及分析   总被引:14,自引:0,他引:14  
2004年10月23日,日本新潟县中越地区发生里氏6.8级强烈地震,死亡40人,受伤4500余人,10万余人无家可归;房屋损坏近14万栋,财产损失约3万亿日元。作者随日本建筑学会地震考察队到该次地震现场进行了考察,报告主要内容包括:地震概况,地震活动性、地震烈度分布及地震波的特征,震害及分析,经济损失,最后给出了这次地震的震害经验和教训。内容可供建筑抗震设计和今后有关规范的修订参考。  相似文献   
148.
简论藏族聚居区可持续发展与产业结构调整导向   总被引:3,自引:0,他引:3  
我国藏族人口聚居区由于受资源—环境、劳动力素质和经济发展水平等因素限制,只能选择兼顾经济—生态环境综合效益的可持续发展道路。为此,作者提出了重点开发藏区旅游服务及其相关第三产业,实现产业结构良性调整,建立具有藏区特色的新型产业结构的有关建议与构想。  相似文献   
149.
博斯腾湖是全国最大的内陆淡水湖,是新疆南疆地区经济发展和人民生活的主要水源,也是塔里木河下游生态应急输水的直接水源,同时,博斯腾湖还是当地著名的旅游风景区。因此,在发展当地旅游业的同时,要兼顾博斯腾湖的生态环境,实现生态环境与经济发展“双赢”的目的,而要实现这个目的的关键在于如何在当地开展生态旅游。  相似文献   
150.
As a global pollutant, high levels of mercury (Hg) have been found in remote ecosystem due to the long range atmospheric transport. In this study, a total of 60 fish samples were collected from four rivers across the Tibetan Plateau to study the accumulation of Hg in remote and high-altitude aquatic environment. The total Hg (THg) and methylmercury (MeHg) in fish muscles ranged from 11 to 2097 ng/g dry weight (dw) (average: 819 ng/g dw) and from 14 to 1960 ng/g dw (average: 756 ng/g dw), respectively. Significantly positive linear relationships were observed between the THg (r = 0.591, p < 0.01, n = 36) and MeHg concentrations (r = 0.473, p < 0.01, n = 36) with the trophic level of fish from Lhasa River, suggesting trophic transfer and biomagnification of Hg in this aquatic ecosystem. Moreover, the THg levels in fish had significantly positive correlations with the length (r = 0.316, p < 0.05, n = 60) and weight (r = 0.271, p < 0.05, n = 60) of fish. The high levels of Hg were attributed to the slow growth and long lifespan of the fish under this sterile and cold environment. Risk assessment revealed that the consumption of Oxygymnocypris stewartii, Schizothorax macropogon, Schizothorax waltoni, Schizopygopsis younghusbandi and Schizothorax o'connori would lead to a high exposure to MeHg.  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