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621.
NASA未来25年固体地球科学规划及其启示   总被引:3,自引:1,他引:2  
美国国家航空与航天局固体地球科学工作组2002年提出了未来25年“固体地球科学整体规划建议”。地球表面总是在变化着,理解这些变化即是一项深刻的科学挑战。高速发展的空间观测技术,使得在行星表面变化特征的表述、监测与预报方面的能力获得革命性飞跃。研究应该以自然灾害的近期预测为目标。如地震,火山爆发及山崩等。整体规划建议包括:科学挑战问题、观测战略、核心研究项目、信息系统、技术发展以及当前(1~5年)、近期(5~10年)和长期(10~25年)目标。  相似文献   
622.
Tephrabase was launched on the World Wide Web in 1995 as a tool for tephrochronological research. In order to facilitate the identification, correlation and dating of tephra deposits, this database may be interrogated through multiple routes, including by source volcano, date, location, and tephra chemistry; datasets include stratigraphy, geochemistry, chronology and spatial information. Currently all the European data refer to Late Quaternary Icelandic‐sourced tephras, post‐12 k yr BP. The sites (62) where the tephra deposits are found include Iceland, the United Kingdom, Ireland, the Faroe Islands, Sweden and Russia. In addition, there are also data on tephra layers in central Mexico. Use of Tephrabase highlights the importance of selected geochemical data, but this has to be used with care as major element characteristics alone do not always produce unique definitions for single tephra deposits. For the most accurate results multiple criteria must be used. Tephrabase can be found at http://www.tephrabase.org . Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
623.
简要回顾了上海天文台在 2 0 0 3年的科研工作情况。  相似文献   
624.
In this study, NSGA‐II is applied to multireservoir system optimization. Here, a four‐dimensional multireservoir system in the Han River basin was formulated. Two objective functions and three cases having different constraint conditions are used to achieve nondominated solutions. NSGA‐II effectively determines these solutions without being subject to any user‐defined penalty function, as it is applied to a multireservoir system optimization having a number of constraints (here, 246), multi‐objectives, and infeasible initial solutions. Most research by multi‐objective genetic algorithms only reveals a trade‐off in the objective function space present, and thus the decision maker must reanalyse this trade‐off relationship in order to obtain information on the decision variable. Contrastingly, this study suggests a method for identifying the best solutions among the nondominated ones by analysing the relation between objective function values and decision variables. Our conclusions demonstrated that NSGA‐II performs well in multireservoir system optimization having multi‐objectives. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
625.
朱永宜  王稳石 《探矿工程》2008,35(9):1-5,10
松科一井的科学目标之一,是通过厘米级样品的取样与分析,建立全球范围内可对比的、高分辩率的陆相白垩系综合地质剖面,将传统地质学百万年的时间分辨率提高到万年尺度。因此,岩心采取率指标对松科一井的地质研究具有极其重要的意义。根据主井不同地层,研发与选用硬质合金、PDC、孕镶金刚石3类12种结构形式的钻头和2种隔液保形单动双管取心钻具,采用转盘单回转与螺杆马达+转盘复合回转钻进工艺,在长井段复杂地层取心钻进163041 m,获原状砂样采集率8207%、岩心采取率9492%的技术指标。详细介绍了取心钻具结构与钻柱组合、取心作业的难点,及相应的工艺措施与技术效果。  相似文献   
626.
设计井深1810 m、完钻井径157 mm、需在松辽湖盆穿透一层含油气构造的松科一井(主井)科学钻探工程,采取自制底架提升平台高度安装井口防喷设施、改造TJS-2000E型水井钻机升降系统提高设备起重能力、研制水力出心装置克服加长加重大口径钻具出心困难、引进石油钻井高速离心除泥机控制泥浆固相含量、根据工程条件无附件焊接套管表层固井等配套技术,成功地完成了国家“973计划”项目“白垩纪地球表层系统重大地质事件与温室气候变化”对工程的规定任务,为高质量、低成本实施大陆环境科学钻探工程探索出了一条可行之路。  相似文献   
627.
Professor Duzheng YE's name has been familiar to me ever since my postdoctoral years at MIT with Professors Jule CHARNEY and Norman PHILLIPS, back in the late 1960 s. I had the enormous pleasure of meeting Professor YE personally in 1992 in Beijing. His concern to promote the very best science and to use it well, and his thinking on multi-level orderly human activities, reminds me not only of the communication skills we need as scientists but also of the multi-level nature of science itself. Here I want to say something(a) about what science is;(b) about why multi-level thinking—and taking more than one viewpoint—is so important for scientific as well as for other forms of understanding; and(c) about what is meant, at a deep level, by "scientific understanding" and trying to communicate it, not only with lay persons but also across professional disciplines. I hope that Professor YE would approve.  相似文献   
628.
Mangroves are an important terrestrial carbon reservoir with numerous ecosystem services. Yet, it is difficult to inventory mangroves because of their low accessibility. A sampling approach that produces accurate assessment while maximizing logistical integrity of inventory operation is often required. Spatial decision support systems (SDSSs) provide support for integrating such a sampling design of fieldwork with operational considerations and evaluation of alternative scenarios. However, this fieldwork design driven by SDSS is often computationally intensive and repetitive. In this study, we develop a cyber-enabled SDSS framework to facilitate the computationally challenging fieldwork design that requires the efficacious selection of base camps and plots for the inventory of mangroves. Our study area is the Zambezi River Delta, Mozambique. Cyber-enabled capabilities, including scientific workflows and cloud computing, are integrated with the SDSS. Scientific workflows enable the automation of data and modeling tasks in the SDSS. Cloud computing offers on-demand computational support for interoperation among stakeholders for collaborative scenario evaluation for the fieldwork design of mangrove inventory. Further, this framework allows for harnessing high-performance computing capabilities for accelerating the fieldwork design. The cyber-enabled framework provides significant merits in terms of effective coordination among science and logistical teams, assurance of meeting inventory objectives, and an objective basis to collectively and efficaciously evaluate alternative scenarios.  相似文献   
629.
海绵城市建设有关问题讨论   总被引:6,自引:0,他引:6       下载免费PDF全文
海绵城市建设目前已成为众多行业和科技领域的讨论热点之一,也面临众多争议,海绵城市建设的内涵、目标、内容和效果等均存在不同认识。针对中国城镇化过程中面临的主要水问题,结合参与海绵城市试点建设评审、考察以及对国外海绵城市的调研情况,从城市水文过程的角度,系统解析了海绵城市的概念,就海绵城市建设的目标与指标、建设功能与发展方向、城市地下排蓄系统、建设管理体制等若干问题展开了讨论。核心观点认为,海绵城市是对中国城市水系统的综合治理,也是城市人居环境的重构,功能综合是海绵城市建设成功的前提,海绵城市的建设应以河湖水系为核心,需要流域和城市的整体规划设计,海绵城市建设应该基于多部门、跨行业的优势互补、合作交叉,按照整体规划、系统布局的方式协同推进。  相似文献   
630.
《China Geology》2021,4(4):571-584
The Philippine Sea is the largest marginal sea in the Western Pacific Ocean and is divided into two parts by the Kyushu-Palau Ridge (KPR). The western part is the West Philippine Basin, and the eastern part consists of the Shikoku and Parece Vela basins. Based on surveyed data of massive high-resolution multibeam bathymetric data and sub-bottom profiles data collected from the southern section of the KPR from 2018 to 2021, this paper analyzes the topographic and geomorphological features, shallow sedimentary features, and tectonic genesis of the southern section of the KPR, obtaining the following conclusions. The southern section of the KPR has complex and rugged topography, with positive and negative topography alternatingly distributed and a maximum height difference of 4086 m. The slope of seamounts in this section generally exceeds 10° and is up to a maximum of 59°. All these contribute noticeably discontinuous topography. There are primarily nine geomorphological types in the southern section of the KPR, including seamounts, ridges, and intermontane valleys, etc. Among them, seven independent seamount groups are divided by five large troughs, forming an overall geomorphological pattern of seven abyssal seamount groups and five troughs. This reflects the geomorphological features of a deep oceanic ridge. Intramontane basins and intermontane valleys in the southern section of the KPR are covered by evenly thick sediments. In contrast, sediments in ridges and seamounts in this section are thin or even missing, with slumps developing locally. Therefore, the sediments are discontinuous and unevenly developed. The KPR formed under the control of tectonism such as volcanic activities and plate movements. In addition, exogenic forces such as underflow scouring and sedimentation also play a certain role in shaping seafloor landforms in the KPR.©2021 China Geology Editorial Office.  相似文献   
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