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   622篇
  免费   23篇
  国内免费   43篇
安全科学   39篇
废物处理   3篇
环保管理   175篇
综合类   270篇
基础理论   69篇
污染及防治   27篇
评价与监测   32篇
社会与环境   46篇
灾害及防治   27篇
  2024年   2篇
  2023年   9篇
  2022年   7篇
  2021年   24篇
  2020年   25篇
  2019年   10篇
  2018年   15篇
  2017年   19篇
  2016年   26篇
  2015年   24篇
  2014年   26篇
  2013年   53篇
  2012年   38篇
  2011年   31篇
  2010年   36篇
  2009年   28篇
  2008年   25篇
  2007年   34篇
  2006年   30篇
  2005年   30篇
  2004年   18篇
  2003年   18篇
  2002年   15篇
  2001年   20篇
  2000年   18篇
  1999年   15篇
  1998年   11篇
  1997年   10篇
  1996年   6篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   5篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1986年   5篇
  1985年   5篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   3篇
  1979年   5篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
排序方式: 共有688条查询结果,搜索用时 31 毫秒
101.
天津市滨海新区地震地质灾害评价与分区研究   总被引:1,自引:1,他引:0  
收集了天津市滨海新区大量的工程地质勘察资料,针对滨海新区场地工程地质条件,从地震地质背景、历史震害的影响出发,依照相应规范和地质类比等方法,通过滨海新区活动断层影响、砂土液化、软土震陷的评判,探讨了滨海新区在未来强震作用下可能出现的地震地质灾害类型及空间分布特征。  相似文献   
102.
国家级新区具有产城融合发展的示范作用,这种示范作用是否达到政策预期是值得探讨的。研究基于产城相互作用机制,构建了产城融合指标体系,运用熵值法、耦合协调度模型对舟山群岛新区和西海岸新区两个地区2014—2018年产业发展与城市功能的发展水平,以及两者之间的协调度进行了测度和分析。结果发现:①两新区初期均呈现出不同程度的不平衡状况,但整体趋于良性发展。②后期两区在一定程度上实现了产城融合,不过发展空间仍然较大。③两新区由于发展条件不一,呈现出不同的发展态势。鉴于此,国家级新区在推进城市产城融合时应遵循因地制宜的原则,及时根据新区的发展现状采取相应的发展调控策略。  相似文献   
103.
New particle formation (NPF) event at multi rural sites in China Identifying the characteristics of NPF event Comparing NPF event between clean and polluted conditions Quantifying contribution to the cloud condensation nuclei Implication of climate and air quality Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were performed to study new particle formation (NPF) events at Shangdianzi (SDZ), Mt. Tai (TS), and Lin’an (LAN) stations representing the background atmospheric conditions in the North China Plain (NCP), Central East China (CEC), and Yangtze River Delta (YRD) regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm−3·s−1, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm·h−1 at SDZ, TS, and LAN, respectively. The NPF event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1–2 times higher. Approximately 12%–17% of all NPF events with nucleated particles grow to a climate-relevant size (>50 nm). These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei (CCN) number concentration can be enhanced by approximately a factor of 2–6 on these event days. The mean value of the enhancement factor is lowest at LAN (2–3) and highest at SDZ (~4). NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.  相似文献   
104.
新中国成立以来的新疆土地开发   总被引:4,自引:0,他引:4  
新中国成立以来,新疆的土地开发经历了三个时期:①1950-1977年以开荒扩大耕地面积为主,耕地面积虽不断增加,但经历了"大跃进"和"十年动乱"干扰,农业生产水平低,粮食仅能实现低水平自给,个别年份还要调入;②1978-1995年耕地面积没有增加,以提高单产为主,粮食单产大幅提高,并逐步压缩粮食面积,增加棉花播种面积,不仅实现粮食自给,还建成全国棉花基地;③1995-2009年,实行提高单产与扩大耕地面积并举,粮棉产量进一步大幅提高,粮食单产高于全国平均水平,建成全国最大的产棉区,总产占全国近二分之一。60多年来新疆土地开发虽取得了巨大成绩,但对生态环境破坏严重,现有耕地已达到水资源承载能力,今后总体上不宜再开荒,而应通过土地整合,提高绿洲内净耕地利用系数,发展节水灌溉,不断提高土地生产力。  相似文献   
105.
Disposal of sewage sludge in the New York Bight Apex (12-Mile Dump Site) ceased at the end of December 1987. Previous efforts to quantify the effects of sludge were hindered by the inability to obtain true replication. the cessation of dumping afforded the opportunity to apply the technique of replication in time, also known as a Before/After, Control/Impact design. Conditionally, this method allows one to separate treatment effects from the natural differences that confound many environmental impact studies. the Environmental Processes Division of the Northeast Fisheries Center, National Marine Fisheries Service sampled the benthic environment of the New York Bight Apex from June 1986 through September 1989 using a sample design based on the technique of replication in time.

Three dominant species (rock crab, Cancer irroratus; little skate; Raja erinacea; and winter flounder, Pseudopleuronectes americanus) and total demersal finfish, collected by otter trawl, showed no statistically significant response to the cessation of disposal. American lobster (Homarus americanus) increased in local abundance, but this result was possibly confounded by a change in fishing effort.  相似文献   
106.
《Environmental Hazards》2013,12(3):213-225
In this paper a large-scale community-based disaster risk-assessment project, undertaken in the Dr Kenneth Kaunda District Municipality in the North-West Province of South Africa, is evaluated. In contrast to other disaster risk management consultancy projects in South Africa, this project included a significant skills transfer component to the at-risk communities and local government officials. In this evaluation, the authors draw on their own experiences in implementing this and similar projects, a review of the project management documents is undertaken, and a focus group interview with facilitators involved in the project is used as a primary source. The discussion is further contextualised in terms of community-based disaster risk assessment theory and the existing literature on disaster risk assessment in South Africa. Logistical and data quality issues as well as staff turnover were found to be concerns during the project. From the findings, it is argued that the common practice of outsourcing disaster risk-management projects is not conducive to effective disaster risk management. Local government entities should take responsibility for disaster risk assessment as a continual activity. This is in contrast to the view currently manifesting in South Africa as a set of bureaucratic actions undertaken by consultants to achieve ‘legislative compliance’ for municipalities.  相似文献   
107.
为了更好地利用青岛崂山区地下空间资源,在全面分析该区地形、地质、水文等条件的基础上,结合岩土工程勘察原始数据和现场水样调查分析报告,根据模糊数学理论和专家经验,遴选出地形地貌、地质构造、工程地质、水文地质、洪水淹没、人口密集程度为评价因子并确定各因子的权重,研究构建了该区地下空间利用评价模型。将评价模型与GIS相结合,利用ArcGIS强大的空间分析功能,采用定量分析的方法得到地下空间利用适宜性分区。研究表明青岛崂山区地下空间建设适宜区面积为106.1km^2,占评价区域面积的73.8%;一般区域面积为26.5km^2,占评价区域面积的18.4%;不适宜区域面积为11.14km^2,占评价区域面积的7.8%。  相似文献   
108.
为研究人田泥沙对小开河灌区自然土壤的影响,用分析化验和工程测试等方法,分析了引黄泥沙和输沙人田后土壤颗粒组成、容重、孔隙状况等物理性状。结果表明:引黄泥沙中0.02~0.002mm的细粉粒比例最高,平均39-31%。小开河自然土壤中0.05-0.02mm的粗粉粒比例最高,为53.41%,泥沙中细粉粒和粘粒含量明显高于当地土壤。输沙人田使灌区土壤中0.02—0.002mm的细粉粒和〈0.002mm的粘粒比例明显增加,〉0.02mm的颗粒比例下降,虽有效避免了因渠首集中沉沙造成的土壤沙化和生态环境恶化,但增加了土壤的粘重程度。农田耕作在一定程度上增加土壤通气孔隙比例、降低土壤容重,但土壤毛管孔隙度依旧稳定在40%左右,毛管作用旺盛,使土壤通气状况不能满足作物需求。在黄河三角洲地区输沙入田的泥沙处理,应结合当地土壤的基本性质和水盐运动规律配置泥沙,以免增强当地土壤紧实、通透性差的性状。  相似文献   
109.
为研究入田泥沙对小开河灌区自然土壤的影响,用分析化验和工程测试等方法,分析了引黄泥沙和输沙入田后土壤颗粒组成、容重、孔隙状况等物理性状。结果表明:引黄泥沙中0.02~0.002mm的细粉粒比例最高,平均39.31%。小开河自然土壤中0.05~0.02mm的粗粉粒比例最高,为53.41%,泥沙中细粉粒和粘粒含量明显高于当地土壤。输沙入田使灌区土壤中0.02~0.002mm的细粉粒和﹤0.002mm的粘粒比例明显增加,0.02mm的颗粒比例下降,虽有效避免了因渠首集中沉沙造成的土壤沙化和生态环境恶化,但增加了土壤的粘重程度。农田耕作在一定程度上增加土壤通气孔隙比例、降低土壤容重,但土壤毛管孔隙度依旧稳定在40%左右,毛管作用旺盛,使土壤通气状况不能满足作物需求。在黄河三角洲地区输沙入田的泥沙处理,应结合当地土壤的基本性质和水盐运动规律配置泥沙,以免增强当地土壤紧实、通透性差的性状。  相似文献   
110.
This article explores community-awareness perspectives and actions towards dioxin-related health exposure in Paritutu Community, New Plymouth, New Zealand. The actions are analysed through media reports, covering a 10-year period from 1998 to 2008. Since 1964, Paritutu Community residents have expressed concern about increased morbidity associated with dioxin contamination from a nearby agrichemical plant. Upon investigation, official agencies were at first unable to verify a causal link between dioxin and morbidity, precipitating community activism and increasing public pressure on relevant authorities. Residents played a major role in alleviating further damage to their community by analysing and evaluating data and providing information that ultimately resulted in both official recognition of their environmental health risk and preventative strategies to alleviate their morbidity. This article backgrounds the Paritutu Community Epidemiology approach and evaluates stages in how the Paritutu Community overcame indifference and lack of precaution and exerted influence leading to the removal of the source of contamination and positive policy changes in public health including the setting up of ameliorative health services for affected people. The findings of this research support theories of popular, lay, community and worker epidemiology.  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