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901.
D. Bala Subrahamanyam Radhika Ramachandran K. Sen Gupta Tuhin K. Mandal 《Boundary-Layer Meteorology》2003,107(3):683-695
The upper air data collected from the balloon-borne GLASS Sondes launched from the Oceanic Research Vessel (ORV) Sagar Kanya during the Intensive Field Phase of the Indian Ocean experiment (INDOEX, IFP-99;SK-141 Cruise) are utilized forstudying the variability in the mixed-layer heights observed over the western tropical Indian Ocean and central Arabian Sea. During the entire cruise, typical daytime convective mixed-layer heights (roughly corresponding to 1400 LT) obtained from V and q profiles, were observed to be in the range 200–900 m. Shallowmixed -layer heights are observed, in general, over the Inter-Tropical Convergence Zone (ITCZ). Over the central Arabian Sea, vertical profiles of V and q demonstrate a double mixed-layer structure of the marine atmospheric boundary layer (MABL), which gradually disappears close to the Indian coastline. 相似文献
902.
One of the significant effects of considering soil-structure interaction in the analysis of structures is the increase in
the fundamental natural period compared to the fundamental natural period of a similar structure, fixed at the base. Applied
Technology Council (ATC) originally set forth some provisions to calculate the fundamental natural period of flexible based
structures using the period of a similar structure, fixed at the base, and lateral and rocking stiffness coefficients of the
foundation. These provisions became the basis of current soil-structure interaction recommendations in several building codes.
The fundamental natural periods of structures founded on different types of foundations computed using recommendations of
the ATC are compared with those computed using a simplified model to perform soil-structure interaction of shear-type structures.
Results show that the provisions given in ATC may be used for structures supported on shallow footings but may not be applicable
for structures supported on pile foundations or foundations having the ratio of lateral to rotational stiffness coefficients
different from those of shallow foundations. An equation, similar to the equation recommended by ATC, is presented to estimate
the fundamental natural period of structures supported on pile foundations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
903.
沉降控制复合桩基的试验研究及适用范围探讨 总被引:1,自引:1,他引:1
沉降控制复合桩基在上海软土地区得到了广泛的应用,但某住宅小区由于其地质条件的特殊性,不能满足上海市< 地基基础设计规范>(DGJ08-11-1999)中沉降控制复合桩基对桩端持力层的特定要求,超出了其适用范围,通过多组原位试验研究,探讨了沉降控制复合桩基在这种特殊地质条件下桩土共同作用的工作机理,分析了在这种地质条件下应用沉降控制复合桩基的可行性. 相似文献
904.
桩筏基础相互作用分析 总被引:1,自引:0,他引:1
提出了考虑土-桩-筏相互作用的迭代分析方法,可获得筏板的内力和桩身轴力等.考虑了桩筏基础下群桩效应作用的群桩桩顶反力分布、群桩桩端力分布及桩与桩相互作用等问题,使得计算的群桩单桩刚度较合理.同时,具有能考虑土的非线性、成层地基及利用单桩静载试验成果反演分析所得参数运用于群桩分析等特点.采用的8节点等参板单元可适用于分析平面不规则形状及变厚度的薄筏板和厚筏板.用笔者提出的方法对桩筏基础实例进行了分析,研究了桩长对该桩筏基础相互作用的影响,并与实测成果及其他学者研究成果进行了对比,表明了该方法能较合理地分析桩筏基础相互作用. 相似文献
905.
The theory of physical interaction field by a differential geometrical approach combines the deformation field with the physical field (e.g., electromagnetic field), and derives a new tensorial relation between the deformation and the dielectric anisotropy of the crustal rocks. This relation can be applied to dielectric anisotropies of deformed natural rocks such as mylonites or gneisses. The dielectric anisotropies of mylonites are observed to increase as plastic strains of mylonites increase. Moreover, the derived tensorial relation can be linked to the electromagnetic potential field (deformational anomalies) in a deformed crust. A physico-geometrical consideration on this theory of physical interaction field is mathematically similar to ones on the theory of field in the Finsler space or on the concept of a unified gauge field. 相似文献
906.
A technique for modeling transient wave propagation in unbounded media is extended and applied to seismic soil–structure interaction analysis in the time domain. The technique, based on the discontinuous Galerkin method, requires lower computational cost and less storage than the boundary element method, and the time‐stepping scheme resulting from Newmark's method in conjunction with the technique is unconditionally stable, allowing for efficient and robust time‐domain computations. To extend the technique to cases characterized by seismic excitation, the free‐field motion is used to compute effective forces, which are introduced on the boundary of the computational domain containing the structure and the soil in the vicinity of the structure. A numerical example on a dam–foundation system subjected to seismic excitation demonstrates the performance of the method. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
907.
908.
This paper is concerned with application of the h-adaptive finite element method to dynamic analysis of a pile in liquefiable soil considering large deformation. In finite element analysis of pile behavior in liquefiable soil during an earthquake, especially considering large deformation of liquefied ground, error due to discretization in the zone near the pile becomes very large. Our purpose was to refine the approximation of the finite element method. The updated Lagrangian formulation and a cyclic elasto-plastic model based on the kinematic hardening rule were adopted to deal with the nonlinearity of the soil. The mixed finite element and finite difference methods together with the u-p formulation and Biot's two-phase mixture theory were used. To improve the accuracy and increase the efficiency of finite element analysis, an h-adaptive scheme that included a posteriori error estimation and h-version mesh refinement was applied to the analysis. The calculated results of effective stress were smoothed locally by the extrapolation method and smoothed stress was used to calculate the L2 norm of the effective stress error in the last step of the calculation of each time increment. The mesh was refined by a fission procedure based on the indication of the error estimate As a numerical example, a soil–pile interaction system loaded cyclically was analyzed by our method. 相似文献
909.
FanAiwu TangJiaxiang LiLi YangJun 《中国地质大学学报(英文版)》2005,16(1):79-83
The investigation of sliding isolation is mainlyfocused on the response of a structure subjected to asingle directional earthquake excitation. Fan andTang (2001) studied the slide limited friction (S LF)base isolation system, using a sequential exponentialfriction model. Zhang and Cheng (2001) studied theisolated effect of a sliding bearing as a friction damp er. Xiong and Yu (2002) studied the numerical meth od of sliding isolation system. But studying a singlecomponent of e… 相似文献
910.