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221.
Numerical simulation on mining-induced water inrushes related to geologic structures using a damage-based hydromechanical model 总被引:2,自引:1,他引:1
A large number of statistics indicate that water inrush has a direct relationship with geological structures such as fault
and karst collapse columns. Understanding the mechanism of water inrushes controlled by geologic structures is of vital importance
for adopting effective measures to prevent their occurrence. The work begins with formulization of a damage-based hydromechanical
model based on elastic damage theory. Next, the model is numerically implemented with finite element method by employing a
finite element package called COMSOL Multiphysics, and is also validated against some existing experimental observations.
Finally, the model is used to simulate the mining-induced groundwater inrushes when the effect of faults and karst collapse
columns is considered in the numerical simulation, and some suggestive conclusions for preventing water inrushes and optimizing
underground mining operations are drawn. 相似文献
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Landform‐oriented flow‐routing algorithm for the dual‐structure loess terrain based on digital elevation models 下载免费PDF全文
The loess landform in the Loess Plateau of China is with typical dual structure, namely, the upper smooth positive terrain and the lower cliffy negative terrain (P–N terrain for short). Obvious differences in their morphological feature, geomorphological mechanism, and hydrological process could be found in the both areas. Based on the differences, a flow‐routing algorithm that separately addresses the dual‐structure terrain would be necessary to encompass this spatial variation in their hydrological behaviour. This paper proposes a mixed flow‐routing algorithm to address aforementioned problems. First, the loess landform surface is divided into P–N terrains based on digital elevation models. Then, specific catchment area is calculated with the new algorithm to simulate the water flows in both positive and negative terrain areas. The mixed algorithm consists of the multiple flow‐routing algorithm (multiple‐flow direction) for positive areas and the D8 algorithm for negative areas, respectively. The approach is validated in two typical geomorphologic areas with low hills and dense gullies in the northern Shaanxi Loess Plateau. Four indices are used to examine the results, which show that the new algorithm is more suitable for loess terrain in simulating the spatial distribution of water accumulation, as well as in modeling the flow characteristics of the true surface by considering the morphological structures of the terrain. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Marieke Ahlborn Torsten Haberzettl Junbo Wang Karoline Henkel Thomas Kasper Gerhard Daut Liping Zhu Roland Mäusbacher 《Boreas: An International Journal of Quaternary Research》2017,46(2):229-241
A possible asynchronicity of the spatial and temporal moisture availability on the Tibetan Plateau has been a controversial subject of discussion in recent years. Here we present the first attempt to systematically investigate possible spatial and temporal variations in moisture availability by examining two lakes, Tangra Yumco and Nam Co, on an east–west transect on the southern Tibetan Plateau using identical proxies for palaeoenvironmental reconstruction. In this study, an independent record from Tangra Yumco was analysed applying a multi‐proxy approach to reconstruct variations in moisture availability since the Lateglacial. Results were subsequently compared with previously published records from Nam Co and additional records from Tso Moriri (northwestern Himalaya) and Naleng Co (southeastern Tibetan Plateau). Our results show that Tangra Yumco was at least partially ice covered prior to 17.1 cal. ka BP. A temperature rise after 17.1 cal. ka BP probably resulted in thawing of the permafrost. At 16.0 cal. ka BP moisture availability increased, representing an initial monsoonal intensification. Warmer conditions between 13.0 and 12.4 cal. ka BP and cooler conditions between 12.4 cal. ka BP and the onset of the Holocene reflect the Bølling‐Allerød and Younger Dryas. At the onset of the Holocene moisture availability rapidly increased, with moisture highest prior to 8.5 cal. ka BP when temperatures were also highest. After 8.5 cal. ka BP the moisture availability gradually decreased and showed only minor amplitude variations. These findings are consistent with the records from large lakes like Nam Co, Tso Moriri, and Naleng Co, revealing a synchronous pattern of moisture availability on the southern Tibetan Plateau. 相似文献
228.
In this paper, the numerical manifold method (NMM) is extended to study wave propagation across rock masses. First, improvements to the system equations, contact treatment, and boundary conditions of the NMM are performed, where new system equations are derived based on the Newmark assumption of the space–time relationship, the edge‐to‐edge contact treatment is further developed for the NMM to handle stress wave propagation across discontinuities, and the viscous non‐reflection boundary condition is derived based on the energy minimisation principle. After the modification, numerical comparisons between the original and improved NMM are presented. The results show that the original system equations result in artificial numerical damping, which can be overcome by the Newmark system equations. Meanwhile, the original contact scheme suffers some calculation problems when modelling stress wave propagation across a discontinuity, which can be solved by the proposed edge‐to‐edge contact scheme. Subsequently, the influence of the mesh size and time step on the improved NMM for stress wave propagation is studied. Finally, 2D wave propagation is modelled, and the model's results are in good agreement with the analytical solution. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
229.
Jianting Zhu 《Hydrogeology Journal》2012,20(1):135-141
An approach is presented to quantify sensitivity of advective contaminant travel time to porosities of hydrogeologic units (HGUs) along the flowpaths when the porosities of different HGUs are correlated. The approach is an extension of the previous sensitivity analysis technique for independent input porosity cases. It is applicable in situations where a calibrated groundwater flow model exists, but a full contaminant transport model is not available. Three sensitivity indices are introduced based on the decomposition of covariance between the advective contaminant travel time and individual input porosities of HGUs. When the input HGU porosities are correlated, the three sensitivity indices quantify the total, intrinsic and correlated contributions from each individual HGU porosity, which should be considered in order to determine the relative importance to the uncertainty in advective contaminant travel time of the input HGU porosities contributing either independently or correlatedly. Two simple one-dimensional flow examples are presented to illustrate the applications of the approach to scenarios when each HGU has distinct porosity and situations of spatially variable porosity field. The approach is applicable to more complex multi-dimensional cases where advective contaminant travel time can be calculated based on simulated flow results from groundwater flow models. 相似文献
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