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   50篇
  免费   11篇
  国内免费   40篇
测绘学   6篇
大气科学   18篇
地球物理   9篇
地质学   51篇
海洋学   9篇
综合类   7篇
自然地理   1篇
  2022年   4篇
  2021年   11篇
  2020年   3篇
  2019年   4篇
  2018年   3篇
  2017年   3篇
  2016年   9篇
  2015年   9篇
  2014年   2篇
  2013年   2篇
  2012年   3篇
  2011年   2篇
  2010年   4篇
  2009年   1篇
  2008年   1篇
  2007年   4篇
  2006年   5篇
  2005年   2篇
  2002年   2篇
  2001年   1篇
  2000年   2篇
  1998年   3篇
  1997年   5篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1991年   2篇
  1987年   1篇
  1985年   1篇
  1983年   2篇
排序方式: 共有101条查询结果,搜索用时 281 毫秒
71.
“源控论”再认识——以四川盆地天然气勘探为例   总被引:2,自引:1,他引:1  
烃源作为成藏的首要条件,没有陆相、海相之分、没有地域之别,也没有油藏、气藏的不同。在海相过成熟碳酸盐岩干气区由系烃源层、煤系烃源层形成的烃源,制约着气藏的形成与展布。  相似文献   
72.
大气输送的环境背景场   总被引:14,自引:0,他引:14  
任阵海  苏福庆 《大气科学》1998,22(4):454-459
根据环境管理和控制观点提出大气环境质量属于资源。欲解决在哪些地方开发环境资源有可能得到最大和最长久的持续发展,在哪些地方是开发利用和环境保护相结合的地区,采用环境背景场研究是比较适宜的途径。为此,提出大气环境背景场的网络矩阵输送模型并利用我国大量历史资料制作出全年各季我国大气输送的环境背景场图。根据这些成果对我国各类输送型输送计算方法及各地区大气输送的环境资源背景场的影响进行了分析。  相似文献   
73.
Eighteen samples of hydrothermal sediments from the Jade hydrothermal field in the central Okinawa Trough have been analyzed. Sulfur isotopic values for 10 sulfide samples vary from 5.2 × 10~(-3) to 7.2× 10(-3), δ~(34)S values for 7 sulfate samples vary from 16.3 × 10~(-3) to 22.3 × 10~(-3), and 1 native sulphur sample has a δ~(34)S value of 8.2× 10~(-3). The major sources of sulfur for hydrothermal sediment are intermediate to acid volcanic rocks and sea water sulfate, and it is possible that the partial sulfur of hydrothermal sediment is from the pelagic sediment by the interaction between hydrothermal fluid and sediment. The reasons of causing the distinct differences in sulfur isotopic values for sulfide samples from hydrothermal sediment ( compared with other hydrothermal fields), are the differences in the sources of sulfur, the magmatic activity and the tectonic evolution in different hydrothermal fields. The sulfur evolution is a long and complex process in the seafloor hydrothermal system  相似文献   
74.
价值工程浮标体现了浮标技术的最新发展,80年代以来美国先后开发出VENOMAD浮标和VE3m圆浮标。本文介绍90年代以后开发的VEWSD漂浮流标,以供借鉴。  相似文献   
75.
The grain size composition of detrital sediments in Hole U1438A from the Amami Sankaku Basin(ASB) in the northwest of the Philippine Sea since the last 350 ka was analyzed. The result shows that the mean grain size of the detrital sediment is about 13.1 μm, ranging from 0.04 to 160 μm. The grain size distribution displays a four-peak pattern and positive skewness. Four independent grain size components were separated by using Weibull distribution function. The ultra-fine component varies from 0.04 to 0.9 μm, with a size mode at about 0.3 μm, which may be genetically related to marine authigenetic clay. The fine-grained fraction ranges from 0.2 to 32 μm, with a size mode at about 3.5 μm, and slightly coarser than the eolian dust of the North Pacific. We argued that this fraction was mainly derived from Asian dust. The coarse-grained and ultra-coarse-grained fractions show distinct size mode at about 10 μm and 40 μm, and range from 0.3 to 90 μm, and from 3 to 160 μm respectively. Both the coarse and ultra-coarse components represent volcanic materials which were mainly derived from the ridges and islands around ASB. The variation of the ratio of environmentally sensitive size population 1.3~2.2 μm/28~40 μm was similar with the ratio of fine-sized component (Asian dust) and coarse-sized component (volcanic material) (0.9~3 μm/>10 μm), showing higher value during glacial period than that during interglacial, which is also identical with the variation of the mass accumulation of eolian dust in the North Pacific and Chinese Loess Plateau, and grain size in Chinese Loess Plateau. The increased ratio responded to the enhanced aridity of Asian continent and strengthened East Asia Winter Monsoon (EAWM)/westerly during glacial period. We argued that the increase of eolian fraction was driven by the enhanced aridity of Asian continent and strengthened East Asia Winter Monsoon (EAWM)/westerly during glacial period. Therefore, the ratio of 0.9~3 μm/>10 μm can be used as a proxy of the increased aridity and enhanced atmospheric circulation of Asian continent. These results suggest that the grain size composition of the detrial sediment in the ASB can be used to reconstruct the history of Asian aridity and atmospheric circulation.  相似文献   
76.
根据机载扫描仪的特点和遥感用户的要求,精心研制了在脱机状态下运行的CCT格式器。其主要功能:(1)将模拟磁带上的多光谱遥感信息数字化,制成便于计算机处理的通用格式化产品——计算机兼容磁带(CCT);(2)读出CCT上的数据,进行图像的快速显示或硬拷贝;(3)对指定的子区目标,进行快速查找与定位。 本文详细论述CCT格式器硬件和软件设计特点,给出磁带数据格式,介绍一些使用情况。该格式器不仅作为机载扫描仪的主要配套设备之一,而且也适合那些需要处理大量磁带数据的图像处理系统。  相似文献   
77.
78.
To investigate the relationship between volcanic activity and sediment record on regional and temporal scales,158 surface sediment samples were collected from the East China Sea Shelf to the northern Okinawa Trough (OT),and two cores recovered in the northern and southern OT,respectively.Mineralogy,grain-size,and geochemical analyses of those samples show that:1) volcanic glass,volcanic-type pyroxene,hypersthenes,and magnetite increase in sediment influenced by volcanic activity;2) sediment grain sizes (and...  相似文献   
79.
地震作用下隔震简支梁桥碰撞反应的振动台试验   总被引:2,自引:0,他引:2  
由地震引发的碰撞是影响桥梁地震反应以及造成桥梁破坏的重要因素。本文对地震作用下隔震简支梁桥的碰撞反应进行了振动台试验。设计制作1个两跨简支的隔震梁桥模型,试验研究了梁间隙、邻梁质量比、隔震支座类型等参数对桥梁碰撞反应的影响。试验结果表明邻梁间隙、邻梁质量比、隔震支座类型等参数对桥梁的碰撞反应有着显著的影响。邻梁间隙越大,碰撞次数越少;邻梁质量比越大,撞击力越大。铅芯橡胶支座比板式橡胶支座耗能能力更强,可以有效降低邻梁之间的撞击力甚至避免碰撞发生。从而为桥梁防碰撞设计提供了可靠的试验依据。  相似文献   
80.
Intensity forecasting is one of the most challenging aspects of tropical cyclone(TC) forecasting. This work examines the impact of assimilating high-resolution all-sky infrared radiance observations from geostationary satellite GOES-13 on the convection-permitting initialization and prediction of Hurricane Joaquin(2015) with an ensemble Kalman filter(EnKF)based on the Weather Research and Forecasting(WRF) model. Given that almost all operational global and regional models struggled to capture Hu...  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