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   292篇
  免费   52篇
  国内免费   51篇
测绘学   16篇
大气科学   5篇
地球物理   41篇
地质学   235篇
海洋学   29篇
天文学   3篇
综合类   31篇
自然地理   35篇
  2023年   1篇
  2022年   9篇
  2021年   11篇
  2020年   7篇
  2019年   12篇
  2018年   6篇
  2017年   11篇
  2016年   18篇
  2015年   11篇
  2014年   21篇
  2013年   18篇
  2012年   16篇
  2011年   12篇
  2010年   11篇
  2009年   21篇
  2008年   22篇
  2007年   19篇
  2006年   14篇
  2005年   13篇
  2004年   17篇
  2003年   11篇
  2002年   15篇
  2001年   22篇
  2000年   12篇
  1999年   16篇
  1998年   10篇
  1997年   2篇
  1996年   12篇
  1995年   6篇
  1994年   5篇
  1993年   6篇
  1991年   3篇
  1987年   2篇
  1986年   1篇
  1983年   1篇
  1978年   1篇
排序方式: 共有395条查询结果,搜索用时 687 毫秒
181.
合理厘定西南天山构造属性,不仅对天山大地构造单元的准确划分具有重要科学意义,而且对中亚造山带的古生代构造演化也至关重要。通过对西南天山乌什北山地区的地质填图和构造解析,识别出5期构造变形,包括2期逆冲推覆构造。对主期逆冲推覆构造进行几何学、运动学研究表明,该逆冲推覆构造在空间上具有由北向南逆冲的运动学指向,并由北向南表现出由逆冲推覆构造的根带向前锋带变化的构造样式。根据逆冲推覆构造的物质组成及变形样式,认为西南天山乌什北山一带应属于塔里木板块北缘逆冲推覆构造带,从而为区域构造单元划分及西南天山晚古生代以来的构造演化过程提供构造变形方面的依据。  相似文献   
182.
地层是多重的,岩石地层及其单位是多种的。文中对多种岩石地层的概念、单位命名方案提出了意见,并对它在实际中的应用作了初步的尝试。  相似文献   
183.
The volcanosedimentary units of Late Mesozoic-Tertiary age that outcrop in the Southeast Anatolian orogenic belt are commonly referred to as the Maden complex. There is a long-lasting controversy over its definition, age, stratigraphic and structural position, and the origin, and thus, the orogenic evolution. To solve this problem, large strips across the Southeast Anatolian orogenic belt have been studied extensively, and different rock groups which were regarded previously as the Maden unit have been differentiated. Their major characteristics and differences have been identified. The Maden unit sensu stricto is here redefined as a volcanosedimentary succession of Middle Eocene age representing a short-lived back-arc basin which reached the stage of an embryonic ocean. Presently, the Maden group occurs mainly within the lower nappe stack of the nappe zone of the Southeast Anatolian orogen. It rests stratigraphically on an amalgamated nappe package consisting of the different metamorphic tectonic units and, in turn, is overlain tectonically by the upper nappe units.  相似文献   
184.
谭双喜 《湖南地质》2001,20(3):233-236
发展多种经营企业,是社会主义市场经济的需要,是地勘单位体制改革的必然趋势,产权单一,事企不分,人才匮乏、技术滞后,观念陈旧,市场不畅,是影响部分地勘单位多种经营企业发展的主要因素,只有在体制、科技和市场开拓等方面进行改革创新,才是地勘单位多种经营企业自我生存,自我发展的正确道路。  相似文献   
185.
GIS支持下的不规则单元划分及地质信息提取   总被引:2,自引:0,他引:2  
在矿产资源定量预测中,单元是预测模型与地质信息联系的桥梁,是统计分析的基础。传统的规则网格单元划分方法虽然给矿产预测的计算机化带来了方便,但也存在许多问题。作者在本文中初步论述了在地理信息系统的支持下不规则地质体单元的划分方法,以及利用GIS的空间数据分析功能提取出不规则单元中的地质信息。  相似文献   
186.
A need exists for a reliable and long-term water supply for the 285,000 inhabitants of the Turku area in southwestern Finland. In response to this need, there are plans to replace the present water supply from the surface sources with artificially infiltrated groundwater from a Quaternary esker aquifer called the Virttaankangas aquifer. New sedimentological studies of the Virttaankangas area have revealed the complexities of the esker system and its surrounding glacial, glaciofluvial, and glaciolacustrine geology. This led to the characterization of the hydrogeological units of the aquifer, the result of which has been a three-dimensional (3-D) truly integrated solids model that represents the geometry, interrelationships, and hydrostratigraphy of the study area. The 3-D model was made with EarthVision geologic modeling software. The 3-D geological model of the Virttaankangas aquifer can be used for planning the infiltration of river water into the aquifer and to understand the geologic and geographic boundaries of the hydrogeologic units hosting the groundwater reserve and the geologic relationships between the units. Another major outcome of this study is a powerful visualization tool that will be provided to municipal and government authorities who must understand the geologic complexities involved with water-resource planning prior to their decision making. Electronic Publication  相似文献   
187.
Introduction At the juncture of Qinghai-Xizang, Ordos and Alxa blocks lies the Qinghai-Xizang plateau, an area with complicated topographic and morphologic features, strong tectonic activities and frequent earthquakes (many large-magnitude earthquakes have taken place), has become a focal area for geoscience study. Many geophysical and geological surveys have been carried out in and around the area, such as deep seismic sounding (DSS), gravimetry, magnetotelluric sounding, magnetic anomaly …  相似文献   
188.
J. Van der Merwe  R.G. Cawthorn   《Lithos》2005,83(3-4):214-228
Exposures in a now-infilled pit mined for platiniferous UG2 chromitite in the Bushveld Complex, South Africa, are described. The layer of chromitite is underlain by anorthosite, providing a dramatic colour contrast. The interface between these two rock types shows evidence of various scales of irregularities. In plan view, small circular depressions, less than 3 cm across and 5 mm deep, occupy about 20% of the surface. Between them, the contact is planar. The anorthosite, immediately underlying the chromitite, has a planar fabric visible in thin sections that is not disturbed beneath these small depressions. Another set of depressions occurs, about 40 cm in diameter and with variable depth (< 40 cm). Again they are approximately circular. Larger structures, called potholes, reach several metres. No regular distribution pattern is apparent in any of these structures.

Several possible processes are reviewed for the origin of these irregularities, especially the small-scale structures, but none explains all the features noted. These processes include remelting, diapirism, impact-generated dimpling, gas escape, and interference rippling. We present a photographic record of these structures, but present no definitive model for their interpretation.  相似文献   

189.
非均质综合指数法划分储层流动单元   总被引:3,自引:0,他引:3  
李祖兵  罗明高  马斌  刘静 《新疆地质》2005,23(2):203-206
近年来,流动单元概念已被广泛用于储层研究中,取得了较好的效果.但怎样充分利用反映流储层及流动非均质性的各个参数来划分流动单元,目前没有统一的认识,献中多局限在传统的划分方法上.基于充分利用各个反映储层特性的参数的思想,笔提出了非均质综合指数法划分储层流动单元,并用这种方法研究了新疆油田某井区储层流动单元.由实践验证,这是一种比较行之有效的方法,划分的结果是可靠的.  相似文献   
190.
从分析阻碍地勘单位企业化进程中存在的体制、资源、职工信心和矿业权归属等主要难点问题入手,提出了继续争取国家政策扶持、事企彻底分离、加大产权制度的改革力度、加快企业重组、加快人事制度改革、以及依托大集团优势达到壮大企业经济规模的相应对策.  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