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   356篇
  免费   30篇
  国内免费   36篇
测绘学   27篇
大气科学   10篇
地球物理   62篇
地质学   80篇
海洋学   231篇
综合类   7篇
自然地理   5篇
  2024年   2篇
  2023年   1篇
  2022年   6篇
  2021年   6篇
  2020年   10篇
  2019年   29篇
  2018年   9篇
  2017年   35篇
  2016年   23篇
  2015年   24篇
  2014年   23篇
  2013年   17篇
  2012年   21篇
  2011年   19篇
  2010年   15篇
  2009年   17篇
  2008年   10篇
  2007年   26篇
  2006年   22篇
  2005年   16篇
  2004年   8篇
  2003年   12篇
  2002年   11篇
  2001年   9篇
  2000年   7篇
  1999年   9篇
  1998年   12篇
  1997年   5篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1983年   1篇
  1979年   1篇
排序方式: 共有422条查询结果,搜索用时 203 毫秒
131.
Frequent locations of thermal fronts in UK shelf seas were identified using an archive of 30,000 satellite images acquired between 1999 and 2008, and applied as a proxy for pelagic diversity in the designation of Marine Protected Areas (MPAs). Networks of MPAs are required for conservation of critical marine habitats within Europe, and there are similar initiatives worldwide. Many pelagic biodiversity hotspots are related to fronts, for example cetaceans and basking sharks around the Isle of Man, Hebrides and Cornwall, and hence remote sensing can address this policy need in regions with insufficient species distribution data. This is the first study of UK Continental Shelf front locations to use a 10-year archive of full-resolution (1.1 km) AVHRR data, revealing new aspects of their spatial and seasonal variability. Frontal locations determined at sea or predicted by ocean models agreed closely with the new frequent front maps, which also identified many additional frontal zones. These front maps were among the most widely used datasets in the recommendation of UK MPAs, and would be applicable to other geographic regions and to other policy drivers such as facilitating the deployment of offshore renewable energy devices with minimal environmental impact.  相似文献   
132.
Two anticyclonic subsurface eddies (SSEs) are detected from the in-situ hydrography data of the southern South China Sea (SCS) during 15–25 October 2011. Both SSEs have the lens-shaped water bodies below the thermocline. Their maximum swirl speed appears at the depth of lens׳ core, which is also characterized by a dump in the TS diagram. These eddies do not have an enclosed saline-water or warm-water body in its lens׳ core, which is different from those SSEs reported in other seas. These SSEs should be locally generated by the horizontal shear of the Southeast Vietnam Offshore Current. In the SSE generation site of the southern SCS, there is an upper-layer anticyclonic eddy (AE2) that is right above the SSE (SE2). After leaving its generation site, the eddy loses its energy source and starts to weaken. In this case, the eddy will decay quickly in the upper layer due to the restraint of the thermocline, and finally evolves into a pure subsurface eddy (i.e. SE4).  相似文献   
133.
本文简要介绍地下管线探测工程中监理的职责,参照的技术依据和主要工作流程;并结合实践经验,重点介绍在项目开展的各阶段监理检查的内容与方法,各项成果精度的统计及项目质量的评价。  相似文献   
134.
The paper presents an overview of the recent contributions of centrifuge modelling to the understanding of soil-structure interaction and the development of design and predictive methods in the field of mobile jack-up drilling rig foundations. Both advantages and limitations of the centrifuge methods are detailed and key examples are presented. The benefits provided by centrifuge modelling to the development of analysis methods that are now being used within the jack-up industry are highlighted. To conclude, industry trends and research opportunities are discussed, as is the possible role of the geotechnical centrifuge in finding solutions to these new needs.  相似文献   
135.
136.
Structural monitoring is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in case of the offshore jacket-type platforms due to the underwater structural parts subjected to the marine environmental conditions. This work is an experimental investigation on a laboratory model of a jacket platform with the objective of establishing a baseline finite element (FE) model for long-term structural health monitoring for this type of structures. A robust damage diagnosis system is also developed which is less sensitive to both the measurements and the modeling uncertainties. Experimental vibration tests are conducted on a physical platform model to obtain dynamic characteristics and then, the initial FE-model of the intact structure is developed to determine them numerically. Some differences between numerically and experimentally identified characteristics emerge due to various uncertainties in the FE-model and measured vibration data. To minimize these differences, initial FE-model is updated according to the experimental results. The updated FE-model is employed to predict the changes in the dynamic characteristics under variety of damage scenarios which are imposed by reducing the stiffness at the components of the model. Fuzzy logic system (FLS) and probabilistic analysis is developed for linguistic classification of damage and global damage diagnosis. Incorporation of the FLS fault isolation technique into FE-model updating method are proposed and evaluated for two different FLS methods to develop a vigorous damage diagnosis method. The efficiency of the technique is validated by different damage scenarios foreseen on the physical model. This technique is shown to be effective for diagnosing the presence of degradation and quantify it.  相似文献   
137.
研究采用GPS技术进行长距离输气(油)管道沿线地质灾害监测的理论和方法,主要分析滑坡体表面的形变,同时结合雨量监测和裂缝监测分析滑坡体的形变.研究表明:GPS技术可以有效地对地质情况复杂区域的地质灾害体进行监测,分析其滑移状态,为工程的灾前治理提供科学依据.  相似文献   
138.
The paper explores value chain governance through a discourse approach to an event which included an exhibition and a conference. This approach appears promising for investigating industries in their formative phase and is particularly relevant for new renewable energy sectors. By studying the European offshore wind value chain, the paper investigates the coupling between wind industries and offshore industries as an encounter of various conventions. The key speakers at the conference, particularly those from the utility companies, introduced new principles for organizing the value chains they are leading, in order to reduce costs, and turn the immature sector into a mature one. Their storyline of industrialization by standardization breaks, however, with the storyline demonstrated by the firms in offshore oil and gas, and maritime industries at the exhibition. The latter offshore suppliers find evidence of quality in their business history and their trust-based relations to their clients. Theoretically the paper contributes to the global value chain governance debate by offering another perspective on power. The discourse approach helps us explain how influential actors could enforce one convention over another. The paper contributes methodically by suggesting a discourse approach to events. Events appear as a significant arena for negotiating industry formation and convenient for researcher’s data gathering for text analysis.  相似文献   
139.
基于Stamp平台,开发了广州市地下管线三维管理系统,实现了海量的地上三维建(构)筑物、地表地形地貌模型、地下三维综合管线以及地铁等其他地下空间设施模型的一体化建模、浏览、查询、统计、分析,本文对系统的三维数据库(模型)、功能、应用及特色进行了介绍。  相似文献   
140.
Plans are being made to construct Dalian Offshore Airport in Jinzhou Bay with a reclamation area of 21 km2. The large-scale reclamation can be expected to have negative effects on the marine environment, and these effects vary depending on the reclamation techniques used. Water quality mathematical models were developed and biology resource investigations were conducted to compare effects of an underwater explosion sediment removal and rock dumping technique and a silt dredging and rock dumping technique on water pollution and fishery loss. The findings show that creation of the artificial island with the underwater explosion sediment removal technique would greatly impact the marine environment. However, the impact for the silt dredging technique would be less. The conclusions from this study provide an important foundation for the planning of Dalian Offshore Airport and can be used as a reference for similar coastal reclamation and marine environment protection.  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