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171.
国家数字地震台网分中心的数据管理与服务   总被引:8,自引:0,他引:8  
国家数字地震台网分中心是中国数字地震观测系统的资料收集、处理、管理、保存和提供各种服务的中心。该中心在结构上采用网络式结构,在上采用分布式结构。根据“95010” 总体设计要求和各单位所承担的任务,中网中心由两部分组,一部分是国家防震减灾中心的测震中心,另一部分是国家数字地震台网分中心,国家数字地震台网分中心设在中国地震局地球物理研究所内,文章对分中心的技术系统、数据管理和数据服务进行全面地介绍。  相似文献   
172.
东北集装箱运输网络的建设与优化探讨   总被引:7,自引:2,他引:7  
韩增林  安筱鹏 《地理科学》2001,21(4):308-314
作为一种新型的运输方式,集装箱运输不仅实现了运输的高效化,信息化,门对门,而且改变了传统的货源组织方式和运输体系,这种改变不仅体现在集装箱枢纽港和支线港的分化,而且体现在集装箱运输内陆网络体系的建设上,以集装箱港口,运输通道,内陆中转站为主而形成的内陆运输网络正在改变着传统的货源组织方式,集装箱运输网络发展滞后也在一定程度上制约着内陆运输的集装箱化水平和集装箱的运输效率,本文论述了集装箱运输网络形成和发展的一般规律,并在此基础上深入分析了东北集装箱运输网络的发展现状,存在问题及内陆运输的规划。  相似文献   
173.
论述了周期-频率谱方法在分析数字化地震记录中的应用。结果表明该方法对识别各类振动的性质较为有效,所形成的一整套分析流程适用于各种地震数字记录分析。  相似文献   
174.
最佳地电台台址条件与环境条件的讨论   总被引:3,自引:0,他引:3  
李正南  张德信 《地震》1997,17(1):80-97
地电台观测地电阻率及其变化以研究地震活动规律,首要的问题是如何选择或评估其台址的优劣,选取最佳地电台台址。文中讨论了地电台台址的地质构造条件、测区地下介质结构条件、介质水文条件、地形地貌条件、电磁干扰等对地电台站观测效能的影响,为选建和评估地电台台址提供较全面、系统的依据。  相似文献   
175.
Tidal creek networks have in 50 years extended over 30 km inland across the coastal plains of the Mary River in northern Australia, invading freshwater wetlands and destroying the associated vegetation. The networks have grown at an exponential rate through a combination of main channel extension and tributary development, with concomitant widening of the creeks. A large tidal range, very small elevational differences over the plains, and the availability of preexisting channel lines (notably in the form of palaeochannels) have been major factors contributing to the rapid rate of expansion. Close parallels exist between these networks and terrestrial networks as regards modes of growth and planimetric properties. A channel is initiated when the diffuse flow of a seepage zone becomes concentrated through localized scour. Subsequent development is characterized by the rapid extension of long first-order channels, with most tributary addition occurring later. Model tests suggest that branching was more likely on exterior links in the early stages but that exterior and interior link branching became more equally likely through time. Although the headward limits of the main creeks seem to have been reached, tributary infilling will continue to progress upstream. Only in the most downstream parts is a stable drainage density being approached. The networks not only satisfy the laws of drainage network composition and the basic postulates of the random model but also depart from topologic randomness in similar ways to terrestrial networks. Both topologic and length properties have changed during evolution but largely at the link rather than network scale. The close correspondence with terrestrial networks may be due to the low relief and the relatively unconstrained nature of growth in which availability of space was the main determining factor.  相似文献   
176.
The capacity of a nation to address the hydrological impacts of climate change depends on the institutions through which water is governed. Inter-institutional networks that enable institutions to adapt and the factors that hinder smooth coordination are poorly understood. Using water governance in India as an example of a complex top-down bureaucratic system that requires effective networks between all key institutions, this research unravels the barriers to adaptation by combining quantitative internet data mining and qualitative analysis of interviews with representatives from twenty-six key institutions operating at the national level.Institutions' online presence shows a disconnect in the institutional discourse between climate change and water with institutions such as the Ministries of Water Resources, Earth Sciences and Agriculture, indicating a lesser involvement compared to institutions such as the Ministries of Finance, External Affairs, Planning Commission. The online documents also indicate a more centralised inter-institutional network, emanating from or pointing to a few key institutions including the Planning Commission and Ministry of Environment and Forests. However, the interviews suggest more complex relational dynamics between institutions and also demonstrate a gap between the aspirational ideals of the National Water Mission under the National Action Plan on Climate Change and the realities of climate change adaptation. This arises from institutional barriers, including lengthy bureaucratic processes and systemic failures, that hinder effective inter-institutional networks to facilitate adaptation. The study provides new understanding of the involvement and barriers of complex multi-layered institutions in climate change adaptation.  相似文献   
177.
Because cities have different attractions for laborers, people migrate from city to city, which may widen the gap between cities. Analyzing the fluxes and directions of migrant flows can help us clarify the regional difference of urban development. Using migration data inferred from passenger travels during 2016 Spring Festival from Tencent Location Big Data, this paper analyzed the unbalanced migration between cities and the spatial difference of urban development. Network analysis methods are employed to evaluate interactions among cities. A community detection method identifies 19 city communities, and the directions of migrant flows in the communities are explored. The PageRank algorithm is employed to evaluate the importance of cities on the migration network and divide the cities into 5 grades, and then the hierarchical structure of the migrant network is illustrated and analyzed. Indices based on migrant populations indicate that the most attractive cities for laborers are along the east coast and that cities in the central region export a significant number of laborers. PageRank and attractiveness values are compare with socio-economic data, and the results indicate that both PageRank and attractiveness are positively correlated with the economic and development level of cities, while PageRank works better. It suggests that Spring Festival travel data in China can be used as migration data, however, it should be facilitated with network methods to disclose the relationship between Spring Festival travel and urban development.  相似文献   
178.
The height of a wave at the time of its breaking, as well as the depth of water in which it breaks, are the two basic parameters that are required as input in design exercises involving wave breaking. Currently the designers obtain these values with the help of graphical procedures and empirical equations. An alternative to this in the form of a neural network is presented in this paper. The networks were trained by combining the existing deterministic relations with a random component. The trained network was validated with the help of fresh laboratory observations. The validation results confirmed usefulness of the neural network approach for this application. The predicted breaking height and water depth were more accurate than those obtained traditionally through empirical schemes. Introduction of a random component in network training was found to yield better forecasts in some validation cases.  相似文献   
179.
180.
Managing ecosystems in a changing environment faces the challenge of balancing diverse competing perspectives on which ecosystem services – nature's benefits – to prioritize. Consequently, we measured and compared how different stakeholders (managers, scientists and fishers) prioritize specific coral reef ecosystem services. Managers’ priorities were more aligned with scientists’ priorities but all stakeholder groups agreed that fishery, education, and habitat were high priorities. However, stakeholder groups differed in the extent to which they prioritized certain services. Fishers tended to assigned greater estimates to fishery and education, managers to culture, and scientists to coastal protection. Furthermore, using network analysis to map the interactions between stakeholders’ priorities, we found distinct synergies and trade-offs in how ecosystem services were prioritized, representing areas of agreement and conflict. In the fishers’ network, trade-offs emerged between two services, both of a higher priority, such as fishery and habitat. Conversely, in the scientists’ network, trade-offs emerged between services of a higher and lower priority, such as habitat and culture. The trade-offs and synergies that emerged in the managers’ network overlap with both fishers’ and scientists’ suggesting a potential brokering role that managers can play in balancing both priorities and conflicts. We suggest that measuring ecosystem service priorities can highlight key areas of agreement and conflict, both within and across stakeholder groups, to be addressed when communicating and prioritizing decisions.  相似文献   
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