全文获取类型
收费全文 | 2795篇 |
免费 | 232篇 |
国内免费 | 154篇 |
专业分类
测绘学 | 575篇 |
大气科学 | 128篇 |
地球物理 | 349篇 |
地质学 | 614篇 |
海洋学 | 365篇 |
天文学 | 22篇 |
综合类 | 203篇 |
自然地理 | 925篇 |
出版年
2024年 | 5篇 |
2023年 | 26篇 |
2022年 | 84篇 |
2021年 | 81篇 |
2020年 | 74篇 |
2019年 | 124篇 |
2018年 | 74篇 |
2017年 | 149篇 |
2016年 | 129篇 |
2015年 | 117篇 |
2014年 | 175篇 |
2013年 | 229篇 |
2012年 | 157篇 |
2011年 | 158篇 |
2010年 | 125篇 |
2009年 | 129篇 |
2008年 | 162篇 |
2007年 | 173篇 |
2006年 | 145篇 |
2005年 | 117篇 |
2004年 | 89篇 |
2003年 | 93篇 |
2002年 | 88篇 |
2001年 | 77篇 |
2000年 | 69篇 |
1999年 | 69篇 |
1998年 | 47篇 |
1997年 | 40篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 25篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1980年 | 1篇 |
排序方式: 共有3181条查询结果,搜索用时 218 毫秒
991.
中冶京诚工程技术有限公司亦庄第二办公区的建筑设计着意于实现建筑对员工的服务功能,体现以人为本的企业精神,强调建筑与周边景观的有机融合。在空间布局、建筑体型、节约能耗等方面突出项目的社会性、经济性以及建绿色环境的特点。 相似文献
992.
丝绸之路经济带建设是当前国家重大战略。合理规划与部署丝绸之路经济带地质调查工作,发挥地质调查工作重要支撑作用,对促进经济建设发展具有重大意义。本文简介丝绸之路经济带概况及重大意义,概述经济带地质矿产与资源概况,分析经济带建设对地质调查工作的需求,并提出了经济带全区基础性地质图件统一编制、促进经济发展的能源与重要矿产资源调查评价、服务城镇化建设的环境地质与工程地质调查、保障用水安全的水文地质调查与成果服务、保障群众生命安全的地质灾害调查与监测预警、服务特色农业发展的重点地区生态农业地质调查、支撑境外战略的优势能源与矿产资源潜力合作调查评价等7大重点工作内容建议。 相似文献
993.
Y. H. Jonathan Tan Jacqueline K. Q. Tham Aayush Paul Umair Rana Hui Ping Ang Nhung T. H. Nguyen Alex T. K. Yee Bryan P. I. Leong Simon Drummond Karenne P. P. Tun 《Singapore journal of tropical geography》2023,44(1):130-148
Rapid urbanization has resulted in the loss of coastal and marine habitats in cities worldwide. The effective conservation of urban coastal ecosystems requires detailed knowledge of their spatial distribution, necessitating high-resolution mapping. Our study produces a high-resolution coastal and marine habitat map and shoreline map for the tropical city-state of Singapore created through pixel-based supervised classification of satellite imagery, bathymetry data and expert ground knowledge. These maps can be used as a base reference for multiple applications including ecological research, conservation and urban planning. They also help identifiy trends in the extent of key coastal habitats, providing insight into their differing levels of vulnerability to loss and potential for restoration to ensure long-term resilience. The method used for mapping shoreline typologies and resulting insights gained, can guide other rapidly urbanizing coastal cities on strategies to assemble useful spatial knowledge for effective conservation of their urban coastal ecosystems. 相似文献
994.
中国机场总规模分层优化测算研究——基于人口覆盖角度 总被引:1,自引:0,他引:1
适宜的机场数量规模是中国机场发展战略和中长期规划的重要研究内容.传统的定性方法难以满足规划的需求,而采用合理的定量测算方法求解中国机场规模对未来的规划更具有参考意义.本文根据不同等级需求点的可达性要求,设置不同的机场服务半径,并规定新建机场腹地人口规模,通过制定位置集合覆盖模型(Location Set Covering Problem,LSCP)和最大覆盖选址模型(Maximal Covering Location Problem,MCLP)的综合修正模型,对中国机场规模进行分层测算.结果表明,不同地、县级需求组合下,在地面道路距离100 km范围内覆盖中国95%总人口时,中国机场规模以370~385个为宜.其中,中部、西部地区地级机场与县级机场均需建设;东北地区需要多新建地级机场,黑龙江省还需新建少量县级机场;东部地区新建少量地级机场以及适量县级机场.对于本文结果中出现的首层地级测算中地级市没有布局机场,但在第二层县级测算时下属县却布局机场,以及同一地级市布局多个县级机场的现象,认为是合理的.测算结果对未来民航机场规划具有一定参考价值. 相似文献
995.
Kaveh Khalili-Damghani Bahram Aminzadeh-Goharrizi Saeed Rastegar Babak Aminzadeh-Goharrizi 《International journal of geographical information science》2014,28(12):2390-2416
The aim of Land-use Suitability Analysis and Planning Problem (LSAPP) is to identify the most suitable parcels of land for future land-uses considering several conflicting criteria. LSAPP can be modeled using a variant of a well-known combinatorial optimization problem called Quadratic Assignment Problem (QAP). In this paper, a multi-objective mathematical model is developed for LSAPP based on QAP modeling. The large-size instances of the proposed multi-objective mathematical model are difficult to solve in a reasonable CPU time using exact algorithms. So, an efficient three-phase hybrid solution procedure is proposed. In the first phase, the compensatory objectives are integrated using Analytic Hierarchy Process (AHP) and Decision-Making Trial and Evaluation Laboratory. Then, based on the aforementioned suitability objective function and other spatial objectives and constraints, a multi-objective LSAPP is constructed. Finally, a hybrid multiple objective meta-heuristic algorithm is proposed to solve the LSAPP. The core of the proposed algorithm is based on Scatter Search while Tabu Search and Variable Neighborhood Search are also utilized. The proposed algorithm is equipped with the concepts of Pareto optimality and Veto Threshold, which improve its efficacy. The proposed algorithm is applied on a real LSAPP case study, in ‘Persian Gulf Knowledge Village’, wherein its performance is compared with a well-known evolutionary computation algorithm called Vector Evaluated Genetic Algorithm (VEGA) using comprehensive statistical analysis. A survey on time complexity of the proposed algorithm is also accomplished. The results show that MOSVNS is significantly superior to VEGA both in single and in multi-objective modes. Furthermore, analysis of time complexity of the proposed algorithm shows that it is of polynomial time and can be applied to significantly larger problems with multiple compensatory and non-compensatory objectives. 相似文献
996.
Haosheng Huang Silvia Klettner Manuela Schmidt Georg Gartner Sven Leitinger Andreas Wagner 《International journal of geographical information science》2014,28(12):2456-2473
Humans perceive and evaluate environments affectively. Some places are experienced as unsafe, while some others as attractive and interesting. These affective responses to environments influence people’s daily behavior and decision-making in space, e.g., choosing which route to take, or which place to visit. In this article, we report on a methodology of using people’s affective responses to environments for enhancing computer-based route planning. More specifically, we explore a crowdsourcing approach to model and collect people’s affective responses to environments; an Affect-Space-Model and a mobile application are developed to facilitate this crowdsourcing approach; a routing algorithm (named AffectRoute) is then proposed to aggregate and integrate the collected data for automatic route planning. Evaluation with human participants shows that the routes generated by considering people’s affective responses to environments are significantly preferred over the conventional shortest ones, which are employed in car navigation systems and many online route planners. In conclusion, considering people’s affective responses to environments contributes to the improvement of automatic route planning. The proposed method can be integrated into existing route-planning services (e.g., location-based services) to provide users with more satisfying routing results. 相似文献
997.
Takeshi Shirabe 《International journal of geographical information science》2014,28(2):314-325
This paper considers the problem of planning a path in a circumstance where its origin is given, but its destination is not specified and is to be selected from among a set of candidate destinations during a trip. A situation like this may be experienced by a group of people who have different preferred destinations, as well as by an individual who is simply indecisive about where to go. To resolve such an uncertainty, one may stay at the origin until he decides on a destination, or choose to proceed on some path that does not overly deviate from a shortest path, whichever destination is eventually chosen, and make a decision on the way. The latter action is sensible when the risk of traveling longer is outweighed by the benefit of buying more time for a better destination decision. The problem of finding such a time-buying path is formulated and a simple algorithm is developed for its solution. Some extensions and applications are also discussed. 相似文献
998.
国内外城乡空间复杂性研究进展及其启示 总被引:1,自引:0,他引:1
我国新时期城乡统筹发展及城乡空间一体化规划仍然面临着城乡关系的恶化和城乡空间分离的挑战。从本质上看,新时期城乡空间统筹规划应是以优化"城乡关系"为重点的城乡空间融合规划,其基础工作则是认识城乡空间的复杂性。当前,在国内掀起新一轮城乡统筹规划热潮的背景下,回顾、梳理国内外城乡空间复杂性研究进展,对指导国内城乡空间统筹规划具有重大意义。文章认为,目前城乡空间复杂性研究仍然以城市单系统为中心,乡村空间"被边缘";研究方法上应加强方法的集成综合,同时强调质性研究和定量分析的结合;在研究内容上应深化城乡关系空间复杂性、城乡关联空间复杂性、城乡空间自组织演化机制与模拟、城乡社会网络空间复杂性等方面的研究。 相似文献
999.
Bayesian belief networks are finding increasing application in adaptive ecosystem management where data are limited and uncertainty is high. The combined effect of multiple stressors is one area where considerable uncertainty exists. Our study area, the Great Barrier Reef is simultaneously data-rich – concerning the physical and biological environment – and data-poor – concerning the effects of interacting stressors. We used a formal expert-elicitation process to obtain estimates of outcomes associated with a variety of scenarios that combined stressors both within and outside the control of local managers. There was much stronger consensus about certain stressor effects – such as between temperature anomalies and bleaching – than others, such as the relationship between water quality and coral cover. In general, the expert outlook for the Great Barrier Reef is pessimistic, with the potential for climate change effects potentially to overshadow the effects of local management actions. 相似文献
1000.
??????????λ???????????μ????????????????????????÷?????????????0.5 m????????????0.2 m??????????????????????????????????????????????????÷???????????????????????2 h????????λ?? 相似文献