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   261篇
  免费   55篇
  国内免费   78篇
测绘学   9篇
大气科学   44篇
地球物理   76篇
地质学   75篇
海洋学   161篇
综合类   11篇
自然地理   18篇
  2024年   1篇
  2023年   4篇
  2022年   6篇
  2021年   12篇
  2020年   13篇
  2019年   13篇
  2018年   12篇
  2017年   18篇
  2016年   8篇
  2015年   20篇
  2014年   27篇
  2013年   27篇
  2012年   27篇
  2011年   12篇
  2010年   10篇
  2009年   22篇
  2008年   17篇
  2007年   23篇
  2006年   26篇
  2005年   18篇
  2004年   14篇
  2003年   9篇
  2002年   9篇
  2001年   2篇
  2000年   4篇
  1999年   2篇
  1998年   4篇
  1997年   4篇
  1996年   7篇
  1995年   3篇
  1994年   5篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1979年   1篇
  1977年   1篇
排序方式: 共有394条查询结果,搜索用时 31 毫秒
201.
边界层风廓线雷达测温系统设计   总被引:1,自引:0,他引:1  
王勇  安建平  卜祥元  贾晓星 《气象》2006,32(10):52-56
风廓线雷达在气象领域的应用越来越广泛,在风廓线雷达基础上增加电声测温系统(RASS)实现大气温度实时探测是一种经济有效的办法。文中介绍了已实现的某RASS系统设计,讨论了RASS测温的原理,针对RASS测温的精度、高度、影响因素等进行了性能分析,论述了系统的实现方案,最后给出了该RASS的实际测温结果和测温谱图,验证了该设计满足系统要求,能实现实时测温。  相似文献   
202.
This study is focused on interpretation of ultrahigh-resolution seismoacoustic data from the northeastern slope of the Ceará Rise (Central Atlantic) acquired using the SES 2000 deep parametric narrow-beam subbottom profiler during cruise 35 of RV Akademik Ioffe in 2011. The geologic nature of most of the detected reflectors is constrained by correlation of the results of seismoacoustic profiling with core data collected in frame of the Ocean Drilling Program (ODP site 929A-E). Detailed seismostratigraphic study of the Upper Quaternary deposits in the study area has implications for better understanding of the role of gravity flows and bottom currents in sedimentation on the NE slope of the rise for the past 1.2 Myr.  相似文献   
203.
In this paper, interannual variations of the ocean dynamic height over the tropical Pacific are diagnosed using three-dimensional temperature and salinity fields from Argo profiles, with a focus on the...  相似文献   
204.
This paper proposes a new method to retrieve salinity profiles from the sea surface salinity(SSS) observed by the Soil Moisture and Ocean Salinity(SMOS) satellite. The main vertical patterns of the salinity profiles are firstly extracted from the salinity profiles measured by Argo using the empirical orthogonal function. To determine the time coefficients for each vertical pattern, two statistical models are developed. In the linear model, a transfer function is proposed to relate the SSS observed by SMOS(SMOS_SSS) with that measured by Argo, and then a linear relationship between the SMOS_SSS and the time coefficient is established. In the nonlinear model, the neural network is utilized to estimate the time coefficients from SMOS_SSS, months and positions of the salinity profiles. The two models are validated by comparing the salinity profiles retrieved from SMOS with those measured by Argo and the climatological salinities. The root-mean-square error(RMSE) of the linear and nonlinear model are 0.08–0.16 and 0.08–0.14 for the upper 400 m, which are 0.01–0.07 and 0.01–0.09 smaller than the RMSE of climatology. The error sources of the method are also discussed.  相似文献   
205.
张志春  袁东亮 《海洋科学》2015,39(5):114-119
针对海洋实测流速资料极其匮乏的事实, 利用2004 年1 月~2009 年12 月月平均的Argo 温盐格点资料, 结合改进的P-vector 方法重构北太平洋绝对地转流流场。与卫星高度计和实测流速的比较以及相关性分析表明, 重构的绝对地转流是可信的, 可以用来研究不同大尺度环流特征及其动力结构。可以为研究海洋动力过程和气候变化提供一套有用的流场数据。  相似文献   
206.
棉兰老岛以东反气旋涡的Argo观测研究   总被引:1,自引:0,他引:1  
报道了2003年1月至10月期间,由布放于西北太平洋中的Argo剖面浮标捕获的位于棉兰老岛以东海域的反气旋涡。该涡中心位于8.7°N、127.6°E附近,距大陆坡不远,沿等深线走向呈椭圆形分布。其长轴(NW-SE)约200km,短轴(NE-SW)长约120km。Argo浮标的漂移轨迹及其在表层及1 500db层的漂移速度场表明,该反气旋涡位于温跃层以下,中层海洋特征。在1 500db层上,涡的外围平均切向速度为11.9—14.0cm.s-1,旋转周期约为40d。温、盐度断面分布表明,该反气旋涡内的温盐结构非常复杂,可能与源自南、北半球的中层水团在涡旋内交汇并发生变性有关。  相似文献   
207.
We deployed two profiling floats in the region south of the Kuroshio Extension in March 2000. Temperature and salinity profiles from a depth of 1500 × 104 Pa to the surface are reported every two and four weeks, respectively. The floats performed very well for first four months after deployment. Later they failed in surfacing for a few months when the sea surface temperature in the region was high. The salinity sensors seemed to suffer from some damage during their failure-in-surfacing period. Despite this trouble, the results clearly demonstrate that the profiling float is a very useful and cost-effective tool for physical oceanographic observation in the open sea. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
208.
Horizontal wind measured by wind profiling radar (WPR) is based on uniform wind assumption in volume of lateral beam. However, this assumption cannot completely meet in the real atmosphere. The subject of this work is to analyze the influence of atmospheric inhomogeneities for wind measurement. Five-beam WPR can measure two groups of horizontal wind components U and V independently, using the difference of horizontal wind components U and V can evaluate the influence of the inhomogeneity of the atmospheric motion on wind measurement. The influences can be divided into both inhomogeneous distribution of horizontal motion and vertical motion. Based on wind measurements and meteorological background information, a new means of coordinate rotation the two kinds of inhomogeneous factor was separated, and the impact in different weather background was discussed. From analysis of the wind measured by type of PB-II WPR (445MHz) during 2012 at Yanqing of Beijing, it is shown that the inhomogeneity of horizontal motion is nearly the same in U and V direction. Both the inhomogeneities of horizontal motion and vertical motion have influence on wind measurement, and the degrees of both influences are associated with changes of wind speed. In clear air, inhomogeneity of horizontal motion is the main influence on wind measurement because of small vertical velocity. In precipitation, the two influences are larger than that in clear air.  相似文献   
209.
Profiling of ponds and bogs using ground-penetrating radar   总被引:2,自引:0,他引:2  
Ground-penetrating radar (GPR) is an electromagnetic technique that has shown particular promise in profiling bogs and freshwater ponds. GPR systems operate in a manner similar to sonar (acoustic) methods, and can complement or be used in place of sonar. GPR pulses can penetrate through shallow fresh water and into bottom sediments, providing detailed information about sediment stratigraphy, obstructions, and depth to bedrock. Peat thickness in bogs can also be readily obtained using a GPR survey. The ability to accurately determine depths in ponds, lakes, and bogs prior to coring is extremely useful for investigations in palynology. By allowing one to see into and obtain configuration and thickness of bottom sediments, GPR surveys permit placement of a core where it will yield optimum information. Where bog or water surfaces are frozen, GPR scans can be run directly over the ice.This is the 2nd in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.  相似文献   
210.
Argo剖面浮标的检测及其施放探讨   总被引:1,自引:1,他引:1  
Argo剖面浮标是一种新颖的海洋观测设备 ,它的抛弃式测量特性决定了对其检测和正确施放的重要性。为了确保 Argo剖面浮标在海上长期 (4~ 5 a)工作 ,并能获得可靠的观测资料 ,本文对 Argo浮标的检测和海上(调查船 )施放步骤作了详尽介绍 ,以供借鉴。  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