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   1399篇
  免费   183篇
  国内免费   325篇
测绘学   59篇
大气科学   145篇
地球物理   152篇
地质学   726篇
海洋学   139篇
天文学   92篇
综合类   51篇
自然地理   543篇
  2024年   7篇
  2023年   31篇
  2022年   62篇
  2021年   63篇
  2020年   69篇
  2019年   69篇
  2018年   58篇
  2017年   59篇
  2016年   85篇
  2015年   63篇
  2014年   81篇
  2013年   89篇
  2012年   88篇
  2011年   107篇
  2010年   72篇
  2009年   85篇
  2008年   70篇
  2007年   89篇
  2006年   111篇
  2005年   82篇
  2004年   104篇
  2003年   63篇
  2002年   48篇
  2001年   47篇
  2000年   44篇
  1999年   44篇
  1998年   31篇
  1997年   22篇
  1996年   17篇
  1995年   13篇
  1994年   12篇
  1993年   6篇
  1992年   2篇
  1991年   5篇
  1989年   1篇
  1988年   2篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
排序方式: 共有1907条查询结果,搜索用时 15 毫秒
101.
受人类活动的影响,海洋污染日益严重。我国海岸带、河口和海湾生态系统均受到了不同程度的破坏。海洋生态环境监测传感器的应用可实现实时海洋环境的监测和快速预警,对于预防海洋灾害、调节海洋经济发展与环境之间的矛盾有重要意义。文中归纳了海洋生态环境类传感器所应用的分析检测技术,总结了目前所研发的各类海洋生态环境传感器,预测了传感器的发展趋势,并对我国未来传感器的研究工作提出了建议。  相似文献   
102.
中高纬度大气低频模态研究进展   总被引:1,自引:0,他引:1  
大气低频模态是导致中高纬地区季节及气候变化的主要因素,加强低频模态动力机制的认识对于提高短期气候预测水平具有十分重要的科研意义和应用价值。由于中高纬大气低频环流本身的复杂性,关于其动力机制的研究仍然是大气动力学中重点难点问题。本文简单回顾了激发维持低频模态的前两种机制,即:外源强迫、气流的纬向非均匀性对大气低频模态的影响。从观测事实和模式结果出发,着重介绍了瞬变波与基本气流相互作用激发维持低频模态的第三种机制,且详细阐述了线性假设条件下,瞬变波与基本气流相互作用的动力机制。本文最后针对瞬变波与基本气流相互作用研究中一些尚未解决的问题进行了讨论。  相似文献   
103.
农作物长势遥感监测业务化应用与研究进展   总被引:1,自引:0,他引:1  
农作物长势监测可为田间管理提供及时的决策支持信息和早期估产提供依据。为了更好地研究作物生长过程中不同遥感监测作物长势方法的适用性,从多光谱遥感数据、高光谱遥感数据和微波遥感数据的应用及遥感监测指标与模型模拟方面综述了国内外农作物长势遥感监测研究及业务化应用的最新进展,指出了未来拟重点加强的研究任务,包括高时空分辨率和高光谱分辨率遥感数据的业务化技术、多遥感反演参数协同监测作物长势技术研发、基于遥感信息与作物过程模型的集合预报技术研究、全球尺度作物长势监测业务运行系统研发。  相似文献   
104.
Arctic sea ice and Eurasian climate: A review   总被引:12,自引:0,他引:12  
The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response(e.g., atmospheric circulation, air temperature) to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.  相似文献   
105.
This conceptual review article provides a critical appraisal of Sustainable Consumption and Production research, which is currently framed by two generic positions. First, the ‘reformist’ position, which focuses on firms pursuing green eco-innovations and consumers buying eco-efficient products, represents the political and academic orthodoxy. Second, the ‘revolutionary’ position, which is a radical critique of the mainstream, advocates the abolishment of capitalism, materialism, and consumerism, and promotes values such as frugality, sufficiency, and localism. We find this dichotomous debate problematic, because it is intellectually stifling and politically conservative (in its outcomes). To move beyond this dichotomy, we propose a third position, ‘reconfiguration’, which focuses on transitions in socio-technical systems and daily life practices and accommodates new conceptual frameworks. For each of the three positions, we discuss: (1) the scale and type of change, (2) views on consumption and production in exemplary approaches, (3) underlying theoretical, epistemological and normative orientations, (4) policy implications, and (5) critical appraisal. The conclusion compares the three positions, provides arguments for the fruitfulness of the reconfiguration-position and offers four critical reflections about future Sustainable Consumption and Production research agendas.  相似文献   
106.
The available literature on marine debris from Latin America and the Wider Caribbean Region was collected and linked, reviewing their methodologies and principal results (quantities, composition and spatial-temporal patterns). The study region comprises 52 coastal countries of which only 14 had registers of works on marine debris. A total of 70 works were available and 69 had their full contents accessed. Brazil dominated the available literature with 70% of the documents. Beaches were the most studied environment, and plastics the prevalent form of contamination in the whole region. The exposure of marine biota (species, type of contact, consequences) was highlighted. The studied region, although still little exploited by this sort of research, shows the same contamination patterns observed world-wide. We also contacted 40 researchers in the area, collecting scientific contributions, opinions and suggestions for improvement of this research field. Further advances and new (urgently needed) lines of research are also discussed.  相似文献   
107.
区域地下水演化的地球化学研究进展   总被引:10,自引:0,他引:10       下载免费PDF全文
由于区域地质特征、水文地质条件、气候影响和人类活动的差异性,导致区域地下水演化的地球化学过程复杂、影响因素众多.在总结近年来国内外区域地下水化学演化研究大量成果的基础上,综述了地下水演化的地球化学系统分析方法,地下水演化研究的水文地球化学方法、同位素地球化学和元素地球化学方法和技术以及地下水演化的地球化学模拟方法和技术及常用软件.指出在今后的一段时期内,区域地下水自然演化与人类活动的复合作用、地下水与地表水的相互作用、微生物-水-岩相互作用将是区域地下水地球化学研究的热点领域,其中物理、化学、生物的耦合作用将是区域地下水演化的地球化学研究的重点领域.  相似文献   
108.
青海西部祁漫塔格成矿带找矿新进展及其意义   总被引:16,自引:2,他引:14  
青海省祁漫塔格成矿带位于东昆仑造山带北西段,带内以往开展了以铁为主的找矿工作,发现一批矽卡岩型中型矿床。近年来带内找矿取得了重大突破:①发现一种新类型矿床——"虎头崖"式层控型大型多金属矿床;②低缓磁异常区多金属和铁矿找矿效果显著,发现四角羊-牛苦头大型多金属矿床,野马泉矿区多金属矿规模达到中型,尕林格矿区发现深部厚大的铁矿体。在系统地综合总结这些成果的基础上,探讨了找矿新进展的意义,划分了3处成矿远景区,并初步讨论了各成矿远景区内进一步找矿的方向。  相似文献   
109.
:In the context of high-quality development, the conflicting relationship between tourist areas and surrounding communities has become a severe obstacle to the realization of high-quality economic development. As a theoretical tool to describe the relationship between tourist areas and surrounding communities, the concept of tourism island is of great value in identifying, assessing, and managing the conflicts between tourist areas and surrounding communities. Therefore, it has gradually become a new topic in geography, sociology, economics, and other related disciplines. On the basis of distinguishing and analyzing the three interrelated concepts of tourism enclave, tourism bubble, and tourism island, this article systematically reviewed the research progress from the four aspects of tourism island types, key characteristics, causes of formation, and impacts, and found that the current research still has obvious deficiencies in theoretical framework, empirical research, and governance system. Finally, this article proposed three specific directions for further research based on the shortcomings of the current research. Based on the practice of Chinese tourism development, a theoretical framework of tourism island should be constructed, the formation processes and impacts of tourism island should be explored using diversified methods of analysis, and a multi-dimensional, multi-level, and multi-process regulatory mechanism should be developed. Overall, this article presented a systematic review of the previous research literature on tourism island to show their results and quality; it also clarified the starting point for further research and laid a foundation for new research works. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.  相似文献   
110.
农户是我国农区的微观经济单元,是农业技术采用的行为主体。以农户为对象的农业技术扩散采用行为的研究对于诱导农户行为、提高农业技术的采用效率、促进农区发展具有重要的理论和应用价值。从研究视角、研究方法、研究内容3个方面对国内外相关研究成果进行较为系统的梳理,总结评述最新进展和特点,并在此基础上对农户技术采用行为的研究趋势进行展望,希冀有助于推进国内对农户技术采用行为的深入研究,进而为促进农业技术扩散与推广、提高农业科技成果转化率提供参考。  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