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321.
基于非线性理论的边坡稳定性评价模型 总被引:18,自引:0,他引:18
边坡稳定问题涉及到各类水利、港工、铁路和工业民用建筑工程。由于影响边坡稳定性的因素较多,而且其变形破坏机理复杂,边坡稳定性问题迄今仍然受到理论研究和工程实践的关注。本文采用非线性理论和方法来研究边坡的变形破坏机理,并建立稳定性评价模型。以分叉和突变理论引出突变级数来表征边坡的状态,并用神经网络从中获取稳定性评价和判断的知识,进而构建系统,并对各类边坡稳定状态做出分析评价。实例分析证明了该方法的有效性。 相似文献
322.
Laurence P. Adams 《The Photogrammetric Record》2001,17(98):225-242
In the Preface to his book, The Four Faces of Fourcade, Clare Storrar (1990) wrote: "It is di.cult to appreciate the breadth and depth of Henry Georges Fourcade's intelligence and creative power. He was an intellectual giant, a phenomenon, whose theoretical and practical achievements have never received proper recognition. These were all the more remarkable because he began his original work on photogrammetry when science in South Africa was in its infancy, and he laboured alone far from libraries and other research facilities. His only higher academic training was in land surveying. He was adept in each of four sciences at various stages in his life, but, mainly because of his natural reserve, his reputation was highly compartmentalised. To foresters he was 'the most brilliant forestry officer of his time' to surveyors, he was exceptionally learned in theory and skilled in practice. Photogrammetry was a new subject, unheard of, except by a handful of scientists. In botany, which he took up seriously at the age of fifty-five, his work was highly regarded by leading botanists in South Africa and in Europe. All stood in awe of his extraordinary talent and ability. Some were frightened of him. But few were able—in fact, not even the best brains were wholly qualified—to grasp fully the tremendous intellectual stature and potential of this protean man."
This paper briefly describes the historic achievements of Henry Georges Fourcade, with the emphasis on his land surveying and, in particular, his photogrammetric contributions to science. The centenary of one of these, his proposal of a stereoscopic method of photographic surveying, occurs in October 2001. 相似文献
This paper briefly describes the historic achievements of Henry Georges Fourcade, with the emphasis on his land surveying and, in particular, his photogrammetric contributions to science. The centenary of one of these, his proposal of a stereoscopic method of photographic surveying, occurs in October 2001. 相似文献
323.
In this paper an intervening opportunities model with spatial dominance is developed. The usual assumption in spatial theory
is that decision makers are influenced not just by the size of a destination or distance but by these two factors in combination, that is, spatial dominance. Decision-makers will have more knowledge about, and clearly perceive destinations that exert
the greatest amount of spatial dominance on their origins, just as they would primate cities. Thus destinations are ranked
in terms of the spatial dominance calculated for each destination. Empirical verification of the model utilizes state-to-state
migration flow data for the US. Calibration results compare favourably with the traditional intervening opportunities model
and the production constrained gravity model.
Received: 7 October 1999/Accepted: 15 June 2000 相似文献
324.
Two kinds of observational data,fluctuation and mean profile measurements,from a 325 m meteorological tower in Beijing,China,are used to evaluate local scales of velocity and temperature for higher heights by flux-gradient mean profiles and eddy-correlation techniques.A comparison of these methods each other was made in terms of vertical turbulence fluxes for momentum and beat at the same heigbt.The vertical profiles of non-dimensional second moments.such as vertical turbulent fluxes of momentum and heat.velocity and temperature standard deviations,were derived by local similarity theory.The local similarity relations expressed that the vertical distributions of non-dimensional second moment variables were found to be functions of z/Λ and z/h in the stable boundary layer and the function of z/Zi for the convective boundary layer,where A the local Monin Obukhov(M-O) length. h the height of stable boundary layer and Zi the height of mixed-layer.These relations are shown to agree well with the observational data. 相似文献
325.
根据积分变换方法得出了半空间内部作用简谐水平力时的Gree函数.首先,利用Hankel积分变换方法,直接对频域内的Biot波动方程进行求解,得出Biot波动方程的通解;利用通解和半空间内部作用水平力时边界上的边界条件,以及力作用面上的连续性条件,可以得出上述边值问题的解;对于边值问题在变换域内的解进行相应的逆变换,就可以得出频域内的Gree函数.本文得到的线弹性退化解与文献中的结果吻合.最后,文中给出了两个算例. 相似文献
326.
327.
社会信息化、经济全球化与世界地理研究的全息景观化—以韩国地理的全息景观研究为例 总被引:1,自引:0,他引:1
知识经济与传统的农业经济和工业经济显著不同,由它推动着的社会信息化及经济全球化所带来的地理发展效应,无论是在发展因素的加入上,还是在地域的建造上都愈来愈向着全息化的方向发展。与之相应,世界地理的研究范式,也应该向着更为开放、更为兼容化的方向改进。为此笔者提出全息景观论,并以韩国为例,以展示这种理论的科学解释价值。 相似文献
328.
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330.
BP和RBF神经网络技术以其强大的学习功能应用于水资源分类 ,取得了很好的效果。但当不具备已知样本时 ,以上技术很难应用。提出了可塑性较强、无监督的A -K网络模型 ,阐述了其基本原理和算法 ,并将其用于水文水资源研究领域中。实例表明 ,该方法能较理想地解决已知样本的分类问题 ,具有良好的应用前景 相似文献