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   508篇
  免费   146篇
  国内免费   45篇
测绘学   7篇
大气科学   13篇
地球物理   269篇
地质学   350篇
海洋学   22篇
天文学   4篇
综合类   13篇
自然地理   21篇
  2023年   1篇
  2022年   5篇
  2021年   15篇
  2020年   10篇
  2019年   17篇
  2018年   19篇
  2017年   17篇
  2016年   20篇
  2015年   20篇
  2014年   17篇
  2013年   29篇
  2012年   22篇
  2011年   27篇
  2010年   26篇
  2009年   47篇
  2008年   43篇
  2007年   46篇
  2006年   52篇
  2005年   27篇
  2004年   28篇
  2003年   26篇
  2002年   24篇
  2001年   21篇
  2000年   19篇
  1999年   19篇
  1998年   14篇
  1997年   10篇
  1996年   15篇
  1995年   3篇
  1994年   11篇
  1993年   12篇
  1992年   6篇
  1991年   4篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1987年   6篇
  1986年   2篇
  1985年   4篇
  1984年   1篇
  1983年   1篇
  1979年   1篇
  1978年   1篇
  1954年   3篇
排序方式: 共有699条查询结果,搜索用时 7 毫秒
181.
本文介绍了地球物理勘探测井资料的计算机处理中,采用岭回归方法对测井曲线DLW、HG、HGG、DZW进行处理,直接生成岩性柱状图。简要介绍了岭回归的原理和方法并通过实例,经过样本训练,给出了岩性的预测公式,计算结果和计算机绘制的岩性柱状图。该方法的实现对测井资料的计算机解释和成图有较大现实意义。  相似文献   
182.
本文根据大量的泥岩孔隙度实测数据和声波测井资料,探讨了我国东部三水、泌阳和黄骅等晚白垩—第三纪含油盆地的类型。根据泥岩压实曲线计算的剥蚀厚度,可将三个盆地划分为具有严重剥蚀的三水压实型与仅有轻微剥蚀的黄骅压实型两类。前者必须根据剥蚀厚度恢复地层在地史时期的最大埋深,否则将会对油气的勘探带来不良影响。  相似文献   
183.
王喜生  李学军 《地学前缘》2003,10(1):163-169
基于饱和等温剩磁(SIRM)获得曲线遵循累积对数高斯模型(CLG)的假设,利用改进的CLG模型分析,成功地对采自泥河湾河—湖相层上部的许家窑剖面样品所含的主要载磁组分进行了分离;结合先前的岩石磁学结果,进一步验证了高矫顽力的赤铁矿和低矫顽力的磁铁矿/磁赤铁矿为许家窑样品的主要载磁矿物,并对各磁组分对SIRM的贡献进行了定量估算;对CLG模型的优缺点和实用性进行了探讨;结合剩磁矫顽力曲线特征,尝试提出了X参数的概念。  相似文献   
184.
摄影地质快速编录的关键技术研究   总被引:3,自引:0,他引:3  
针对现行水电工程、地下工程施工地质编录方法的不足,进行了摄影地质快速编录技术与方法的研究。在数字相机量测化改造的基础上,综合应用近景摄影测量、图像处理和GIS技术,设计开发了基于数字相机的摄影地质编录信息系统。该系统以高边坡、大洞室为对象,具有数字摄影、正射影像制作、图像镶嵌、编录要素提取与产状量测、编录成果CAD制图等功能,实现了数据采集、机助处理与成图的一体化作业模式,提高了地质编录的工作效率和成图精度,为施工地质编录提供了新的手段与途径。  相似文献   
185.
甘会春  刘树才  武杰 《江苏地质》2003,27(3):164-167
介绍了三极断面测深技术在第四系水源地勘探中的应用。钻探验证结果表明,该方法能够准确地圈定第四系地层中的含水体,可为供水水源地选择提供必要的地质资料。  相似文献   
186.
The objectives of this paper are an understanding of the thermal and hydraulic field because of a negative temperature gradient and cold temperatures in the 1-km-deep borehole of the Hawaiian Scientific Drilling Project (HSDP), located near the coast line. The temperature pattern is attributed to a superposition of thermal and hydraulic processes. In the deeper borehole (HSDP-2, depth 3.1 km) detailed temperature monitoring was performed. Temperature measurements reveal two different thermal regimes. The upper part is characterised by cold temperatures and a negative temperature gradient similar to those observed in the shallow pilot borehole. Below 1100 m, increasing temperatures are observed. Different processes, such as topographically driven groundwater flow, ingress of salt water and conductive heat flow are investigated by numerical modeling. A pure conductive scenario fails to match the temperature measurements, implying that both borehole sections are overprinted by advective conditions. Coupled fluid and heat flow modeling with solute transport yield results that agree with observed temperatures. The results of these simulations suggest that meteoric water flow from the mountain range controls the thermal conditions in the upper part of the borehole. Below this level, the thermal regime is additionally affected by circulation of salt water from the nearby ocean. Each of these flow systems has been observed at other locations: topographically driven fresh water at locations with pronounced topography and ingress of salt water is typical for islands or coastal areas. At Hawaii, they coincide and influence each other, resulting in a salt water interface occurring at greater depth than expected.  相似文献   
187.
This paper details technical aspects associated with electrical conductivity measurements within saturated clays and presents experimental work to show the direct application of electrical techniques to track ionic movement through clay under chemically induced flow. The study confined itself to kaolin using both naturally sedimented samples and consolidated samples. Regarding the latter, a Rowe cell was adapted to allow electrical measurements to be taken both normal and parallel to the direction of loading. Bulk conductivity measurements and measurements on the conductivity of the interstitial pore fluid were used to quantify the pore tortuosity and effective diffusion coefficient of saturated clay. In addition, predicted concentration time curves agreed well with those estimated from conductivity measurements.  相似文献   
188.
The depth profiles of electrical conductance, δ18O,210Pb and cosmogenic radio isotopes10Be and36Cl have been measured in a 30 m ice core from east Antarctica near the Indian station, Dakshin Gangotri. Using210Pb and δ18O, the mean annual accumulation rates have been calculated to be 20 and 21 cm of ice equivalent per year during the past ∼ 150 years. Using these acumulation rates, the volcanic event that occurred in 1815 AD, has been identified based on electrical conductance measurements. Based on δ18O measurements, the mean annual surface air temperatures (MASAT) data observed during the last 150 years indicates that the beginning of the 19th century was cooler by about 2‡ C than the recent past and the middle of 18th century. The fallout of cosmogenic radio isotope10Be compares reasonably well with those obtained on other stations (73‡ S to 90‡ S) from Antarctica and higher latitudes beyond 77‡N. The fallout of36Cl calculated based on the present work agrees well with the mean global production rate estimated earlier by Lal and Peters (1967). The bomb pulse of36Cl observed in Greenland is not observed in the present studies – a result which is puzzling and needs to be studied on neighbouring ice cores from the same region.  相似文献   
189.
This paper is mainly about the calculation of reservoir parameters and the interpretation method for identifying oil/water beds in Ke82 well areas of Junggar basin. It is difficult to determine the reservoir parameters with common logging methods such as core calibration log because of the diversity of minerals and rocks and the complexity of pore structures in the conglomerate reservoir of Junggar basin. Optimization logging exploration is a good method to determine the porosity by establishing the multi-mineral model with logging curves based on the integration of geological, core and well testing data. Permeability is identified by BP algorithm of neural network. Hydrocarbon saturation is determined by correlating Archie‘s and Simandoux formulas. Comparing the exploratory result and core data, we can see that these methods are effective for conglomerate logging exploration. We processed and explained six wells in the Ke82 well areas. And actual interpretation has had very good results, 85 % of which conform to well testing data. Therefore, this technique will be effective for identifying conglomerate parameters.  相似文献   
190.
Sinkholes in dolomitic areas are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. Electrical resistivity imaging, or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. RESTOM surveys were conducted at two sinkhole sites near Pretoria, South Africa. The survey areas are located in the dolomites of the Lyttelton Formation, which forms part of the Malamani Subgroup and Chuniespoort Group of the Transvaal Supergroup. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities.  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