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   1704篇
  免费   142篇
  国内免费   356篇
测绘学   229篇
大气科学   492篇
地球物理   228篇
地质学   505篇
海洋学   203篇
天文学   28篇
综合类   55篇
自然地理   462篇
  2024年   6篇
  2023年   31篇
  2022年   87篇
  2021年   92篇
  2020年   97篇
  2019年   89篇
  2018年   75篇
  2017年   109篇
  2016年   95篇
  2015年   88篇
  2014年   107篇
  2013年   144篇
  2012年   63篇
  2011年   88篇
  2010年   63篇
  2009年   108篇
  2008年   104篇
  2007年   98篇
  2006年   98篇
  2005年   82篇
  2004年   70篇
  2003年   62篇
  2002年   63篇
  2001年   35篇
  2000年   38篇
  1999年   42篇
  1998年   37篇
  1997年   29篇
  1996年   21篇
  1995年   21篇
  1994年   19篇
  1993年   6篇
  1992年   8篇
  1991年   11篇
  1990年   3篇
  1988年   3篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1978年   2篇
  1954年   2篇
排序方式: 共有2202条查询结果,搜索用时 0 毫秒
151.
Dam development in southeastern Turkey is a highly-disputed issue, fanned by the Turkish–Kurdish conflict, socio-environmental and historical–cultural concerns, and international geopolitical interests. This paper focuses on discussions around the Ilisu Dam and shows how different actor coalitions imagine different hydrosocial territories regarding this mega-hydraulic project currently under construction. Imaginaries, counter-imaginaries and endeavours to materialize them go far beyond technical projects, portraying the dam to (re)configure the territory physically, ecologically, socio-economically, symbolically and discursively. The paper embeds competing hydro-territorial constructs and claims within an analysis of governmentality and the multi-scalar and multi-issue politics of dam opponents.  相似文献   
152.
全球观测系统实地观测的内容和要求   总被引:1,自引:0,他引:1  
全球性观测系统在检测,监测和预测地球系统的变化中发挥着越工重要的作用。地球系统的复杂性,多尺度性,非线性性,突变性,非平衡性等要求各种全球性观测系统之间必须加强联系与协调。评述了全球性观测系统联系与协调的发展趋势,并依据《全球性观测系统实地观测的内容和体系纲要》、介绍了全球性观测系统实地观测的内容和规范要求。  相似文献   
153.
基于GPS技术的大型结构建筑物动态监测   总被引:7,自引:4,他引:7  
在回顾传统的结构物震动和位移测量方法的基础上,详细阐述了采用GPS进行大型建筑物动态监测的原理、方法。介绍国内外典型的动态监测实例,提出了监测数据的管理与可视化方案,对未来大型结构建筑物动态监测的技术进行了展望。  相似文献   
154.
This paper presents a quantitative reconstruction of the European late Pleistocene paleoclimate based on 72 rodent assemblages of five sequences from France, Germany and Bulgaria, covering the last interglacial-glacial cycle. They show a pattern of severe changes in temperature, with reduced precipitation during the coldest periods. A tentative correlation between the isotopic and palynological records and the paleotemperature changes is shown. These changes are consistent with variations in atmospheric circulation patterns in response to an expanding-retracting Fennoscandian ice-sheet. They can be attributed to the enhancement-weakening of the Scandinavian-Polar anticyclone and its associated dry winds, the south-north shifting of the North Atlantic Polar Front, and the varying supply of moist air from the Atlantic. Qualitative paleoenvironmental analysis shows broadleaved-deciduous forests in France and Bulgaria during most of the studied period. Taiga and tundra appeared in eastern France during the lower Würm. The German sequence indicates the presence of coniferous forests. These results are broadly consistent with other paleobiological records (mammalian, avian and insect faunas, isotopic record in dental tissue, palynology). The main discrepancies with the paleoclimate inferred from the palynological record are found during the coldest periods and are probably due to the interaction between vegetation, climate, and atmospheric CO2 levels.  相似文献   
155.
GPS-measured land subsidence in Ojiya City, Niigata Prefecture, Japan   总被引:1,自引:0,他引:1  
Land subsidence caused by compression of clay layers in Ojiya City, Japan was measured by global positioning system (GPS) between 1 April 1996 and 31 December 1998.

Three baselines were selected in and around the city, and height difference on a WGS-84 ellipsoid was measured by GPS on each baseline. The ground at the GPS station in the city subsides and rebounds 7 cm every winter and spring, respectively. Measurement accuracy was 9.5 mm standard deviation. Ground water level was observed at a well near the GPS station. Regression analysis between total strain, calculated as ratio of the height difference displacement to the total thickness of the clay layers, and the layers' effective stress change with ground water level change gave good correlation. The slope of regression line 7.0×10−11 m2/N was obtained as an average apparent coefficient of volume compressibility of the layers.  相似文献   

156.
Al James  Bhaskar Vira 《Geoforum》2010,41(3):364-376
This paper explores the lived experiences and aspirational social constructions of call centre work and employment in India’s high profile IT Enabled Services-Business Process Outsourcing (ITES-BPO) industry; the ways in which they differ from those previously documented amongst call centre workers in the Global North (specifically the UK); and the consequences of that geographical reconfiguration of offshored call centre work for the replicability in India of workplace collective bargaining strategies successfully developed in some UK call centres. These issues are analysed using new empirical evidence from a regional survey of 511 non-unionised ITES-BPO workers and 42 in-depth interviews in India’s National Capital Region. Based on this analysis, the paper then discusses the operation, outcomes and ongoing challenges faced by the newly formed ‘Union for ITES Professionals’ (UNITES Pro) in developing an alternative occupational organising model better suited to the particular needs, motivations and preferences of India’s young, mobile, call centre workers. The empirical analysis presented in the paper is located, therefore, within wider debates on the role of geographical context in shaping possibilities for organising white-collar service workers at different ends of global service chains in the new economy.  相似文献   
157.
Multiphase flow modelling is a major issue in the assessment of groundwater pollution. Three-phase flows are commonly governed by mathematical models that associate a pressure equation with two saturation equations. These equations involve a number of secondary variables that reflect the fluid behaviour in a porous medium. To improve the computational efficiency of multiphase flow simulators, several simplified reformulations of three-phase flow equations have been proposed. However, they require the construction of new secondary variables adapted to the reformulated flow equations. In this article, two different approaches are compared to quantify these variables. A numerical example is given for a typical fine sand.  相似文献   
158.
张焕新  曹俊  张成功  沈洪江  袁茂珂 《地质论评》2018,64(2):6402447-6402449
正1地质公园简介中国可可托海世界地质公园位于亚洲中部内陆地区、中国新疆维吾尔自治区阿勒泰地区富蕴县、青河县境内;行政区划隶属新疆伊犁哈萨克自治州阿勒泰地区行政公署。公园总面积2337.90 km2,地理坐标:东经89°29'45″~90°11'54″,北纬46°42'04″~47°43'45″,海拔1072~3234 m(张成功  相似文献   
159.
论地球空间信息科学的形成   总被引:61,自引:3,他引:61  
从分析地球空间信息科学与全球变化监测和社会可持续发展的关系出发,回顾了地球空间信息科学产生的背景,提出地球空间信息科学的定义及内涵,概括了学科当前的发展状况,提出了现阶段学科研究的主要内容,最后,展望了地球空间信息科学的发展。  相似文献   
160.
海陆边缘沉积磷在全球变化研究中的意义   总被引:8,自引:1,他引:8  
从磷的生物地球化学循环的角度,讨论了磷与大气圈O2、CO2的关联模式,并通过研究磷的环境地球化学行为,揭示了海陆边缘沉积磷对古气候、古环境变化的记录及其对指示古全球变化的关键性,同时提出了中国东部沿海近代沉积磷的积累与全球变化的耦合作用关系,在中短时间尺度的全球变化研究中所具有的特殊意义。  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