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121.
不等保护能力纠错编码在水声信息传输中应用的研究 总被引:1,自引:0,他引:1
通过分析水声信道的特性和水声信息源的特点 ,结合信道编码理论与技术的最新进展 ,提出了一种全新的、能适合于水声信息传输的、高性能的不等保护能力纠错编解码方法。 相似文献
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Megan L. Sebben Adrian D. Werner Jessica E. Liggett Daniel Partington Craig T. Simmons 《水文研究》2013,27(8):1276-1285
Studies employing integrated surface–subsurface hydrological models (ISSHMs) have utilized a variety of test cases to demonstrate model accuracy and consistency between codes. Here, we review the current state of ISSHM testing and evaluate the most popular ISSHM test cases by comparing the hydrodynamic processes simulated in each case to the processes found in well‐characterized, real‐world catchments and by comparing their general attributes to those of successful benchmark problems from other fields of hydrogeology. The review reveals that (1) ISSHM testing and intercode comparison have not adopted specific test cases consistently; (2) despite the wide range of ISSHM metrics available for model testing, only two model performance diagnostics are typically adopted: the catchment outflow hydrograph and the catchment water balance; (3) in intercode comparisons, model performance is usually judged by evaluating only one performance diagnostic: the catchment outflow hydrograph; and (4) ISSHM test cases evaluate a small number of hydrodynamic processes that are largely uniform across the model domain, representing a limited selection of the processes of interest in well‐characterized, real‐world catchments. ISSHM testing would benefit from more intercode comparisons using a consistent set of test cases, aimed at evaluating more catchment processes (e.g. flooding) and using a wider range of simulation diagnostics (e.g. pressure head distributions). To achieve this, a suite of test case variations is required to capture the relevant catchment processes. Finally, there is a need for additional ISSHM test problems that compare model predictions with hydrological observations from intensively monitored field sites and controlled laboratory experiments. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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L. Peruzza A. Rebez D. Slejko P. L. Bragato 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):361-371
Probabilistic seismic hazard maps, in terms of spectral acceleration and uniform hazard response spectra at given sites, considering local soil conditions, represent a much more complete estimate of the seismic hazard than the traditional maps in terms of peak ground acceleration or macroseismic intensity. This is particularly true when the requests of urban planners and engineers have to be met. The present analysis shows how some hazard parameters, such as the effective peak acceleration and the spectrum intensity, can well synthesise the overall information available from traditional probabilistic studies, but also suggests that soil condition is a first-order ingredient for effective seismic hazard mapping at national level. Three Italian towns, damaged by the 1997 Umbria–Marche earthquake sequence, are considered as example to demonstrate that: (1) soil condition dependent uniform hazard spectra well approximate actual spectra recorded during some events of the seismic sequence; (2) for these localities, the design spectrum of the present Italian seismic code does not seem adequate.
These considerations have induced the Italian scientific community to propose an updating of the national seismic zonation on the basis of several hazard parameters, that are described in this paper. 相似文献
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H. R. E. Staines 《Australian Journal of Earth Sciences》2013,60(2):83-106
Abstract Stratigraphic nomenclature in Australia was regulated from 1950 by four successive editions of the Australian Code of Stratigraphic Nomenclature. The International Stratigraphic Guide was adopted for stratigraphic nomenclature in Australia in 1978 and thus superseded the Australian Code. Certain provisions of the Code and certain Australian practices still pertained, however, and these have been formulated as Notes, intercalated with extracts from Chapters 2–5 of the International Guide to form the Field Geologist's Guide to Lithostratigraphic Nomenclature in Australia. Biostratigraphic and chronostratigraphic nomenclatures are excluded. The lithostratigraphic nomenclature of igneous and metamorphic rock units is also excluded, as recommendations are still being formulated. Procedures for reserving, defining, and publishing stratigraphic names are administered by the Stratigraphic Nomenclature Committee in conjunction with the Bureau of Mineral Resources through the Bureau's Central Register of Stratigraphic Names. 相似文献
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"主从相关器"结构的接收机常被用来监测C/A码相关函数相关峰的形变,但受制于相关器数量的影响,在GPS卫星低仰角时,监测器并不能及早地发现信号形变,针对这一问题,该文在"主从相关器"结构的接收机基础上,采用了虚拟相关对技术,通过已知的3组相关对(一组"主相关对",两组"从相关对")和Prompt相关器输出,以码片间距为自变量,采用最小二乘的方法,拟合相关器相关值输出三次曲线。拟合曲线上的点作为构建的虚拟相关对输出,它们与已知相关器的输出一起进入之后的相关函数相关峰性形变监测部分处理。采用此种方法,不仅不会遗漏传统算法用到的待测量,而且能扩大待测量的样本空间。同时,该方法不会因为加入新的待测量产生误测。通过仿真发现,在使用3组相关对和Prompt相关器,且GPS卫星仰角较低时,该算法比传统算法更早监测到C/A码形变。 相似文献
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介绍了C/A码、L2C码以及L5码的生成方式、测距精度及特性,并对GPS系统中测距码的扩充作了简要介绍。 相似文献
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