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   614篇
  免费   36篇
  国内免费   25篇
测绘学   58篇
大气科学   46篇
地球物理   10篇
地质学   89篇
海洋学   30篇
天文学   9篇
综合类   48篇
自然地理   385篇
  2024年   1篇
  2023年   11篇
  2022年   48篇
  2021年   45篇
  2020年   43篇
  2019年   38篇
  2018年   29篇
  2017年   35篇
  2016年   48篇
  2015年   26篇
  2014年   34篇
  2013年   39篇
  2012年   35篇
  2011年   16篇
  2010年   21篇
  2009年   17篇
  2008年   21篇
  2007年   18篇
  2006年   21篇
  2005年   19篇
  2004年   18篇
  2003年   17篇
  2002年   23篇
  2001年   25篇
  2000年   13篇
  1999年   8篇
  1998年   5篇
  1987年   1篇
排序方式: 共有675条查询结果,搜索用时 15 毫秒
191.
通过对区域产业创新发展的影响因素进行分析,在理论研究基础上,采用结构方程方法对影响因素在产业发展创新驱动中的作用方式及路径进行假设和建模,并结合实证进行检验。研究发现,区域产业创新发展驱动的关键影响因素主要包括管理水平、技术环境、经济环境和政策环境,其中管理水平和技术环境因素可以直接作用于产业创新,而经济环境和政策环境因素则需要通过产业发展选择的方式,来间接推动产业创新。最后根据研究结果,提出通过作用于影响因素,强化区域产业创新驱动的具体建议。  相似文献   
192.
While the focus of government climate change policy in many regions is on mitigation, research shows that integrated approaches, focusing equally on mitigation and adaptation, seen in the context of more general sustainability goals, may ultimately yield more productive outcomes. Since 2008, the province of British Columbia has mandated that local governments be carbon neutral in their own operations and has used a suite of policies, outreach and incentive tools to enable them to do so. The Meeting the Climate Change Challenge project explored eleven leading communities in B.C. to empirically examine how climate change policies and innovations are being framed and considered at the local scale.In this paper, we examine the synergies and trade-offs between adaptation, mitigation, and sustainability. Our findings suggest that, among leading communities, pursuing an integrated sustainability strategy (rather than a narrow focus on climate change) has the potential to yield benefits for both adaptation and mitigation in the majority of cases. The findings suggest that communities leading on climate innovation in the province have moved beyond a siloed approach in considering mitigation and adaptation. These findings have implications on integrated decision making at the municipal scale and multi-level governance, identifying both the challenges and the benefits inherent in pursuing multiple priorities simultaneously.  相似文献   
193.
王春杨  张超 《地理科学》2014,(12):1438-1444
以341个地级层面区域作为空间观测单元,以专利申请受理数作为衡量指标,对中国1997~2009年期间地级区域创新产出的时空特征进行了ESDA分析。结果表明:中国地级区域创新产出的地域性特征显著,首先表现为全局上的地理集聚和地带间的巨大差异;但不同于省级空间尺度下地带内部区域创新显著的极化特征,地级空间尺度区域创新却呈现多样化的局部空间依赖模式。整体上,创新产出在地级空间尺度上自然形成2个显著的空间集群,即东部沿海的H-H集群和西部内陆的L-L集群。东部H-H集群在考察期内由东北和华北地区逐渐向山东半岛、长三角和珠三角地区转移,西部L-L集群的空间发展则相对稳定;H-L型集群和L-H型集群主要分布在中部地区和东中西邻接地区,创新的空间过渡特征明显。最后在实证分析的基础上,提出了政策建议和未来研究的方向。  相似文献   
194.
我国注册测绘师制度的实施,有助于推动测绘市场与国际接轨,并提高专业技术人员素质,促进测绘事业的改革和发展.作为职业认证考试,对测绘专业教学具有重要启示.通过对注册测绘师考试大纲的GNSS知识点分布进行剖析,并以此展开课程教学改革探讨,包括讲座责任制教学模式实施、强化实践教学和测绘案例分析能力的提高等,达到GNSS课“促进理论应用于实践、提高GPS案例分析能力,满足国家注册测绘师相关要求”的要求.  相似文献   
195.
Carbon capture and storage (CCS) is increasingly depicted as an important element of the carbon dioxide mitigation portfolio. However, critics have warned that CCS might lead to “reinforced fossil fuel lock-in”, by perpetuating a fossil fuel based energy provision system. Due to large-scale investments in CCS infrastructure, the fossil fuel based ‘regime’ would be perpetuated to at least the end of this century.In this paper we investigate if and how CCS could help to avoid reinforcing fossil fuel lock-in. First we develop a set of criteria to estimate the degree of technological lock-in. We apply these criteria to assess the lock-in reinforcement effect of adding CCS to the fossil fuel socio-technical regime (FFR).In principle, carbon dioxide could be captured from any carbon dioxide point source. In the practice of present technological innovations, business strategies, and policy developments, CCS is most often coupled to coal power plants. However, there are many point sources of carbon dioxide that are not directly related to coal or even fossil fuels. For instance, many forms of bio-energy or biomass-based processes generate significant streams of carbon dioxide emissions. Capturing this carbon dioxide which was originally sequestered in biomass could lead to negative carbon dioxide emissions.We use the functional approach of technical innovations systems (TIS) to estimate in more detail the strengths of the “niches” CCS and Bio-Energy with CCS (BECCS). We also assess the orientation of the CCS niche towards the FFR and the risk of crowding out BECCS. Next we develop pathways for developing fossil energy carbon capture and storage, BECCS, and combinations of them, using transition pathways concepts. The outcome is that a large-scale BECCS development could be feasible under certain conditions, thus largely avoiding the risk of reinforced fossil fuel lock-in.  相似文献   
196.
为依法、公正、及时地做好土地权属争议的调查处理工作,以大量土地权属争议案例为基础,结合现行有关法律法规进行分析、总结,探索建立了以"重在调解、重心下移、部门联动、健全网络"为内容的土地权属争议调处新机制。达到了提高调处效率、降低社会成本的目的。  相似文献   
197.
创新是企业得以生存和持续发展的内在动力,产业集群是对企业创新具有重要影响的一种经济组织形态。产业集群环境下的协同产品创新在实践中得到不断发展,并产生了多方面的积极效应,促进了企业创新和集群发展。基于产业集群的协同产品创新由于存在密集的物资和信息流通,风险传染的可能性很高。从风险传染的内涵界定出发,在集群协同产品创新的创新链分析基础上,归纳了集群协同产品创新的风险传染条件及规律,描述了单一风险流的风险传染机理与过程,并构建了基于SIR模型的集群协同产品创新单一风险传染的过程模型,据此提出了集群协同产品创新风险免疫策略。  相似文献   
198.
从创新和创新体系的概念出发 ,着重介绍测绘技术创新的重要性 ,提出了建立测绘技术创新体系的一系列对策和措施。  相似文献   
199.
Regional innovation system (RIS) is the new research field of modern economic geography in the age of knowledge economy. Based on the researches of regional economic geography, the authors of the paper consider RIS as the integrated and interactive systems with innovation milieu, elements, units, structure and functions. Five aspects of evaluation indicators including innovation input scale and output scale, innovation milieu transition, innovation inner operation, as well as innovation outer impact are worked out for final indicators of RIS scale and quality. According to different RIS situations, three patterns of independent, imitative and cooperative development are put forward for choosing. At the latter part of the paper, we select 12 provincial regions (including three municipalities and one autonomous region) of China for empirical study. The results show that there exists great difference among each region from the aspects of innovation scale and quality mainly owning to the diversification of RIS social and economic milieu, the major innovative units of enterprises, universities and R&D institutes. Finally, the paper points out the innovation development decisions for each region. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 40131010) LIU Shu-guang (1966–), male, a native of Xiajin County of Shandong, Ph. D., associate professor, specialized in regional economic development and regional innovation system. E-mail: dawnliu9631@263.net  相似文献   
200.
总结了在2005年度中国科学院上海天文台的日常科研工作及与其相关的人才培养和引进、科技开发、科研管理、国际合作交流以及精神文明建设等工作中取得的成果。  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