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131.
Application of forecasting models reveals that parameter estimates vary substantially among regions reflecting spatial variation in consumer preferences and behavior. We present a simulation methodology to evaluate the stability in performance of recreation participation models between different regions. The sample data consisted of 632 household interviews obtained via random digit dialing techniques as part of Oklahoma's 1980 statewide survey of outdoor recreation demand. Three variables, the age of the head of the household, the number of household members, and distance to the facility were consistently accurate predictors of participation; the performance of other variables depended directly upon unknown attributes of the specific region. 相似文献
132.
简要介绍了蒙城地震台自1992年以来发生的观测环境保护案例,分析了台站观测环境保护工作的重点和难点,深入探讨了新时期地震台站观测环境保护的特点及其引发的思考。 相似文献
133.
134.
Conditional Nonlinear Optimal Perturbation (CNOP) is a new method proposed by Mu et al. in 2003, which generalizes the linear singular vector (LSV) to include nonlinearity. It has become a powerful tool for studying predictability and sensitivity among other issues in nonlinear systems. This is because the CNOP is able to represent, while the LSV is unable to deal with, the fastest developing perturbation in a nonlinear system. The wide application of this new method, however, has been limited due to its large computational cost related to the use of an adjoint technique. In order to greatly reduce the computational cost, we hereby propose a fast algorithm for solving the CNOP based on the empirical orthogonal function (EOF). The algorithm is tested in target observation experiments of Typhoon Matsa using the Global/Regional Assimilation and PrEdiction System (GRAPES), an operational regional forecast model of China. The effectivity and feasibility of the algorithm to determine the sensitivity (target) area is evaluated through two observing system simulation experiments (OSSEs). The results, as expected, show that the energy of the CNOP solved by the new algorithm develops quickly and nonlinearly. The sensitivity area is effectively identified with the CNOP from the new algorithm, using 24 h as the prediction time window. The 24-h accumulated rainfall prediction errors (ARPEs) in the verification region are reduced significantly compared with the "true state," when the initial conditions (ICs) in the sensitivity area are replaced with the "observations." The decrease of the ARPEs can be achieved for even longer prediction times (e.g., 72 h). Further analyses reveal that the decrease of the 24-h ARPEs in the verification region is attributable to improved simulations of the typhoon's initial warm-core, upper level relative vorticity, water vapor conditions, etc., as a result of the updated ICs in the sensitivity area. 相似文献
135.
《The Journal of geography》2012,111(4):176-178
Abstract Hilltop Geography is a year-long integrated geography program that involves first and second graders in a hands-on laboratory approach to exploring their immediate environment while at the same time providing a stepping stone to their understanding of the world. This article will describe how teachers and students in a rural New Mexico school have been utilizing the semi-arid hills surrounding their building as an outdoor geography learning laboratory, involving parents and the local community in the process. 相似文献
136.
V. Yu. Terebizh 《Astronomy Letters》2004,30(3):200-208
We propose a form of a lens corrector at the prime focus of a hyperboloidal mirror that provides a flat field of view up to 3° in diameter at image quality D80<0.8 arcsec in integrated (0.32–1.1 µm) light. The corrector consists of five lenses made of fused silica. All lens surfaces are spherical in shape, so the system is capable of achieving better images, if necessary, by aspherizing the surfaces. The optical system of the corrector is stable in the sense that its principal features are retained when optimized after significant perturbations of its parameters. As an example, we calculated three versions of the corrector for the Blanco 4-m telescope at Cerro Tololo Inter-American Observatory with \(2\mathop .\limits^ \circ 12\), \(2\mathop .\limits^ \circ 4\) and \(3\mathop .\limits^ \circ 0\) fields of view. 相似文献
137.
138.
Fangdon Yin Daniel Grosjean Richard C. Flagan John H. Seinfeld 《Journal of Atmospheric Chemistry》1990,11(4):365-399
The mechanisms for atmospheric photooxidation of CH3SCH3 and CH3SSCH3 developed in Part I are evaluated by a series of outdoor smog chamber experiments. Measured product yields, including SO2, H2SO4, CH3SO3H and HCHO, are reported. The predictions of the mechanisms developed in Part I are found to be in substantial agreement with the measured concentrations from the smog chamber. By comparison of mechanism predictions and observations, critical uncertainties in the mechanism are identified. 相似文献
139.
建设国家对地观测体系,构筑"数字地球" 总被引:36,自引:2,他引:34
论述了“数字地球”的特征与重要意义,指出对地观测是“数字地球”的核心内容之一。建议中国不失时机地组织建设国家对地观测体系。该体系可在信息获取、处理与应用3个层面上构建,并提出近期中国对地观测应优先发展的领域,以持续地为“数字地球”发展作贡献 相似文献
140.