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   208篇
  免费   12篇
  国内免费   2篇
测绘学   12篇
大气科学   6篇
地球物理   10篇
地质学   42篇
海洋学   6篇
综合类   13篇
自然地理   133篇
  2024年   1篇
  2023年   2篇
  2022年   8篇
  2021年   9篇
  2020年   4篇
  2019年   11篇
  2018年   7篇
  2017年   17篇
  2016年   7篇
  2015年   9篇
  2014年   15篇
  2013年   19篇
  2012年   6篇
  2011年   9篇
  2010年   5篇
  2009年   6篇
  2008年   10篇
  2007年   10篇
  2006年   13篇
  2005年   12篇
  2004年   3篇
  2003年   9篇
  2002年   6篇
  2001年   3篇
  2000年   5篇
  1998年   5篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1988年   1篇
排序方式: 共有222条查询结果,搜索用时 15 毫秒
11.
对古代墓葬出土人骨的研究,可以了解古代人群的健康状况,并可以探讨不同生业模式对古代人群健康状况的影响。中原地区是中国古代文化最发达的地区,也是古代人骨出土最多和考古研究最充分的地区。本文对中原地区比较典型的河南舞阳贾湖遗址和河南灵宝西坡墓地出土人骨进行了全面的骨骼健康状况研究。贾湖遗址以渔猎采集为主要经济形态,距今9000~7800年;西坡墓地以农业为主,距今约5000年。骨骼研究显示,贾湖遗址和西坡墓地的两性身高呈逐渐降低的趋势;口腔疾病研究显示,在龋齿、牙周病、齿根脓疡、牙结石、釉质发育不全等疾病的发病率上,西坡墓地的发病率都明显高于贾湖遗址;身体骨骼研究显示,西坡墓地在退行性关节病、骨质疏松症和贫血等的发病率也明显高于贾湖遗址。这些可能暗示了,古代人群的健康状况在从渔猎采集经济向农业经济转变过程中呈逐渐恶化的趋势。但同时,作为健康指标的重要特征,西坡墓地较贾湖遗址的平均寿命有了明显的提高。结合考古学研究成果,我们认为农业经济虽然在一定程度上对古代人群的健康有一定的负面影响,但农业经济的发展,提供了更稳定的食物供应,养活了更多的人口,使得古代遗址规模不断扩大,社会复杂化逐渐深化,也创造了更多的社会财富,为向文明社会的转化奠定了物质基础。因此,农业经济的转变总体上促进了古代人群的健康状况的发展和文明的进步,农业经济对人类的进步做出了巨大贡献。  相似文献   
12.
Cell phones present new forms of sociality and new possibilities of encounter for young people across the globe. Nowhere is this more evident than in sub-Saharan Africa where the scale of usage, even among the very poor, is remarkable. In this paper we reflect on the inter-generational encounters which are embedded in young people’s cell phone interactions, and consider the wider societal implications, not least the potential for associated shifts in the generational balance of power. An intriguing feature of this changing generational nexus is that while many young people’s phone-based interactions, from their mid-teens onwards, are shifting away from the older generation towards friendship networks in their own age cohort, at the same time they are repositioning themselves – or becoming repositioned – as family information hubs, as a consequence of their phone expertise. The paper draws on mixed-methods research with young people aged c. 9–25 years and in-depth interviews with older age-groups in 24 sites (ranging from high density poor urban to remote rural) across Ghana, Malawi and South Africa.  相似文献   
13.
Conflict over water is a significant phenomenon in many parts of the world where globally linked neoliberal economic activities encroach on the lands of indigenous peoples. This case study from Chile examines how water scarcity affecting indigenous agricultural communities in the Chilean Altiplano has been exacerbated by legally sanctioned mining‐related practices. Notably, the legal framing of the 1981 Water Code promotes private ownership of water rights and enhanced mining activity usually at the expense of the ancestral territorial rights of indigenous communities. In the case of the Atacameño community of Chiu Chiu, a serious decrease in subsistence and agriculture production has been suffered as a consequence of reduced flow in the Loa River, resulting from the water intensive needs and extraction practices of the nearby Chuquicamata mine owned by Codelco, the National Copper Corporation of Chile. Via an analysis of the political ecology of competing rationalities this paper explores how an economic rationality based on utilitarian and reductionist thinking manifested by Codelco has taken precedence locally over a socionatural rationality grounded in holistic thinking and sustainability concerns as articulated by the Chiu Chiu community.  相似文献   
14.
15.
基于历史观测资料,系统地研究了广东省热带气旋(tropical cyclone,TC)风雨及其带来的直接经济损失的空间分布特征。结果表明,粤西沿海地区受TC大风影响最为频繁,但TC经济灾损率和受灾频次在粤西和粤东较重。根据广东省TC风雨和直接经济损失的空间分布特征,将广东分为粤西、粤东、珠三角和粤北4个区域,进而利用演化建模方法建立了广东省各区域TC经济灾损率评估模型。该评估模型模拟的TC经济灾损率与实际值的相关系数达0.66以上,基于该模型对独立样本的预测检验结果与实际值的相关系数达到0.61以上(显著性水平a=0.05)。这表明,基于演化建模方法建立的广东省各区域评估模型在广东省TC灾害评估中有着潜在的应用价值。  相似文献   
16.
Soil was sampled from cropping fields in radial patterns from beneathAcacia albida, Parkia bigloboza(Jacq.) Benth. andEucalyptus camaldulensisDehnh. near Zaria, Nigeria. Results of analysis show a significant coarsening of soil texture and a decrease in organic matter and cation exchange capacity with increasing distance from all three tree species at a depth of 0–15 cm. Concentrations of nitrogen and some exchangeable cations decreased significantly with increasing distance from beneath acacia and parkia, and soil pH decreased with increasing distance from eucalyptus. The implication of the results for land management are discussed in relation to increasing productivity and soil use sustainability.  相似文献   
17.
近几年来,经济发展迅速,土地级别划分及地价水平已有较大的变化,原有的基准地价体系已不能适应现时经济发展的要求,地价体系也亟需修正更新。该文结合拜城县的具体情况,并遵循所选因子与土地的相关性,确定拜城县城区土地定级因素,在分析各定级因素权重的基础上,计算各因素的分值,划分土地等级。通过对拜城县城区的土地进行定级估价作出修正和更新,将对土地的监督管理工作起到良好的促进作用。  相似文献   
18.
Forest tenure reform in the age of climate change: Lessons for REDD+   总被引:1,自引:0,他引:1  
Numerous authors have stressed the importance of guaranteeing and protecting the tenure and human rights of indigenous and other forest-based communities under schemes for reducing emissions from deforestation and forest degradation (REDD, or REDD+); and important international indigenous organizations have spoken out strongly against REDD+. This article examines two specific issues that present risks for local communities: rights to forests and rules for resource use. It draws on the findings of a study conducted by the Center for International Forestry Research (CIFOR) on forest tenure reforms in selected countries in Asia, Africa and Latin America from 2006 to 2008. The study underlines the numerous obstacles faced by communities after rights are won, in moving from statutory rights to their implementation and to access to benefits on the ground. It argues that there is currently little reason to expect better results from national policies under REDD+ without binding agreements to protect local rights.  相似文献   
19.
Water Flows Toward Power: Socioecological Degradation of Lake Urmia,Iran   总被引:1,自引:0,他引:1  
Water is an invaluable resource, and equitable access to it is a fundamental human right. Disenfranchised groups often lose access to water resources because their interests are not well represented by decision makers. Excluding these groups from resource management policy often results in myopic decisions that contribute to further ecosystem damage. We describe the ecological degradation of Lake Urmia in Iran, which has recently experienced increased salinity and declining water quantity. The lake is a UNESCO Biosphere Reserve and Ramsar site, and supports unique biodiversity in the region. The lake's decline is driven by the destruction of Zagros forests and the government's water policies, which diverted water to more politically connected agricultural land users, increasing social inequity and prompting more deforestation. The most straightforward restoration solution is to discontinue the diversions and allow critical inflows to recharge Lake Urmia, preserving the lake and wetlands for migratory birds, tourists, and local communities.  相似文献   
20.
结合部门实际。对江西气象部门如何领会和贯彻落实2005年全省领导干部会议精神,提出了具体的指导意见。讲话指出,全省各级气象部门干部职工,要把思想和行动进一步统一到全省领导干部会议精神上来,围绕为全民创业提供优质气象服务,找准自己的位置,为不同创业主体提供精细化、个性化的气象服务产品。拓宽为全民创业服务的气象信息传递渠道,强化安全气象和资源气象服务,开展全民创业技能培训和创业资讯服务,营造优化有利于全民创业的气象政务环境。努力满足全民创业对气象服务的迫切需求。讲话还强调,全省气象干部职工要强化创业理念,大力培育气象创业文化;加强气象能力建设,加快提升气象现代化水平和效益;适应中国气象事业发展战略,加快全省新一轮气象业务技术体制改革;坚持改革创新,做大做强做优气象科技服务;加强队伍建设,为事业发展提供智力支持和组织保证,努力在全民创业的热潮中,实现江西气象事业在新的起点上更快更好的发展。另外。讲话在总结分析上半年工作的基础上,结合全省领导干部会议精神。对2005年下半年的工作进行了全面的部署。认为2005年下半年,全省气象部门要狠抓目标管理,积极做好气象服务工作,下大力气促科技服务上新台阶;要加强与有关部门的共建共享工作。及时完成“十一五”规划的编制。大力推进业务技术体制改革和现代化建设;要加强党建和气象文化建设,并根据《江西省气象局关于加强基层台站建设的实施意见》,以及《全省县(市、区)气象局“五大工程”建设考评办法》。抓好基层台站建设。  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