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141.
高考前夕经常会看到铺天盖地的仿真训练、道听途说的小道信息,搞得学生心神紧张、焦虑重重。备考不能心急,心急就会浮躁。高三地理冲刺阶段教学应做到理性的回归,不急不躁,扎实做好解题技法和规范答题的训练,突出补缺、提力、规范。本文从保温、加固、规范三个方面谈高三地理冲刺阶段的复习备考。 相似文献
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Using the mesoscale model MM5, the development of initial condition uncertainties at different scales and amplitudes and their influences on the mesoscale predictability of the "0185" Shanghai heavy precipitation event are investigated. It is found that different initial conditions obtained from different globe model analyses lead to large variations in the simulated location and strength of the heavy precipitation, and the scales and amplitudes of the initial condition perturbations significantly influence the model error growth. The power spectrum evolution of the difference total energy (DTE) between a control simulation and a sensitivity experiment indicates that the error growth saturates after 12 h, which is the predictable time limit of the heavy precipitation event. The power spectrum evolution of the accumulated precipitation difference between the control and sensitivity simulations suggests a loss of the mesoscale predictability for precipitation systems of scales smaller than 300 kin, i.e., the predictable space for the heavy precipitation event is beyond 300 km. The results also show that the initial uncertainties at larger scales and amplitudes generally result in larger forecast divergence than the uncertainties at smaller scales and amplitudes. The predictable forecasting time and space can be expanded (e.g., from 12 to 15 h, and from beyond 300 kin to beyond 200 km) under properly prescribed initial perturbations at smaller scales and amplitudes. 相似文献
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The Grid-point Atmospheric Model of IAP LASG version 1.0 (GAMIL1.0) is used to investigate the impacts of different convective schemes on the radiative energy budget.The two convective schemes are Zhang and McFarlance (1995)/Hack (1994) (ZM) and Tiedtke (1989)/Nordeng (1994) (TN).Two simulations are performed:one with the ZM scheme (EX_ZM) and the other with the TN scheme (EX_TN).The results indicate that during the convective process,more water vapor consumption and temperature increment are found in the EX_ZM,especially in the lower model layer,its environment is therefore very dry.In contrast,there is a moister atmosphere in the EX_TN,which favors low cloud formation and large-scale condensation,and hence more low cloud fraction,higher cloud water mixing ratio,and deeper cloud extinction optical depth are simulated,reflecting more solar radiative flux in the EX_TN.This explains why the TN scheme underestimates the net shortwave radiative flux at the top of the atmosphere and at surface.In addition,convection influences longwave radiation,surface sensible and latent heat fluxes through changes in cloud emissivity and precipitation. 相似文献
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加权网络是复杂网络研究的一个重要领域,交通网络是一个典型的加权网络.交通网络的发展演化对国民经济的繁荣发展起着至关重要的作用.综合复杂网络的拓扑结构和交通流量计算的顾客选择理论,提出了一种随时间演化基于乘客中转路径的交通系统发展演化模型,并对模型进行了分析和数学验证,分析结果为该模型的点强度、点度和权重分布性质和BBV模型完全一致;网络是无尺度网络,点强度和点度分布都服从幂律分布,并且指数在233~300之间.最后通过仿真实验对演化模型进行仿真,结合中国交通网络的实证分析验证了模型的合理性. 相似文献
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文章提出一种基于谱元法的区域分解算法(DDM-SEM),并将其用于频域弹性波问题的计算.该方法结合了谱元法的高精度以及区域分解法的高并行特性,适合于大尺度弹性波问题的高精度和高效率计算.在DDMSEM算法中,原始的大尺度问题被分解为若干个子区域,每个子区域采用谱元法独立求解,子区域之间的交界面通过频域黎曼传输条件连接.本文提出的区域分解方法在不同的子区域不仅可采用非匹配网格,而且还可以选取不同的插值阶数,实现计算效率最大化.通过对每个子区域的内部自由度和边界自由度进行分离,结合高效和天然并行性的分块LDU直接求解器能快速求解系统矩阵.数值结果验证了该方法的精度和效率,同时也表明DDMSEM算法在计算大规模、多尺度的弹性波模型中展现出数值方法的优越性.同时,本文提出的方法对于频域下多源地震波反问题的计算具有潜在的应用价值. 相似文献
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A Simple Monte Carlo Method for Locating the Three-dimensional Critical Slip Surface of a Slope 总被引:2,自引:0,他引:2
XIE Mowen Institute of Environmental Systems Kyushu University Hakozaki -- Higashi Ku Fukuok Japan College of Resource Engineering the University of Science Technology Beijing Xueyuan Ro Haidian District Beijing China 《《地质学报》英文版》2004,78(6):1258-1266
Based on the assumption of the plain-strain problem, various optimization or random search methods have been developed for locating the critical slip surfaces in slope-stability analysis, but none of such methods is applicable to the 3D case. In this paper, a simple Monte Carlo random simulation method is proposed to identify the 3D critical slip surface. Assuming the initial slip to be the lower part of a slip ellipsoid, the 3D critical slip surface is located by means of a minimized 3D safety factor. A column-based 3D slope stability analysis model is used to calculate this factor. In this study, some practical cases of known minimum safety factors and critical slip surfaces in 2D analysis are extended to 3D slope problems to locate the critical slip surfaces. Compared with the 2D result, the resulting 3D critical slip surface has no apparent difference in terms of only cross section, but the associated 3D safety factor is definitely higher. 相似文献