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421.
为了克服传统遗传算法在优化多目标图像分割参数时易陷入局部收敛和搜索效率低的缺陷,本文提出一种基于智能遗传算法和Otsu法的多目标图像分割方法,并将它应用于航空影像的分割。实验结果表明,本文提出的算法比传统遗传算法可以更加快速、更稳定地获取图像分割的最优阈值。 相似文献
422.
伸臂式结构地震剪力图和弯矩图的理论包络线 总被引:4,自引:3,他引:1
本文以人工工振型作为理论工具、推演出伸臂式结构地震剪力地震弯矩的主、次上界的简练公式。不难理解,上界地震剪力图和弯矩图就分别相当于无数地震剪力图的弯矩图的包络线。文中还推演出主、次上界与等效静力解之间的一个十分简明的理论关系。 相似文献
423.
Juin-Fu Chai Tsung-Jen Teng Chin-Hsiung Loh 《Soil Dynamics and Earthquake Engineering》2004,24(7):527-536
The objective of this paper is to identify the first mode ground period Tg, at each interesting site along Taiwan High Speed Rail (THSR) route, and further, to determine the site-dependent design response spectrum for particular sites with Tg larger than 1 s. In this paper, a linear model of shear wave propagating in a multi-layered half-space is developed to identify the first mode ground period Tg of an interesting site on the basis of the field bore hole data. Furthermore, for each one of the strong ground motion observation stations within the Chiayi-Tainan area, the first mode ground period Tg was identified by either coda waves or pre-event ambient vibrations from the seismograms. In addition, the site-specific parameter Cv in defining the normalized response spectrum was also determined based on the observed strong ground motions at the specified observation station, and hence the empirical function between Tg and Cv can be regressed for this interesting area. Therefore, for a particular site along THSR route within the Chiayi-Tainan area, the site-specific parameter Cv can be determined from the regressed empirical function by the identified first mode ground period Tg, and further, used to develop the site-dependent design response spectrum. 相似文献
424.
以辩证唯物主义为指导 ,从哲学角度总结了重要地质灾害的发生、发展与演变规律 ,探讨了地质灾害的基本概念和防治中的方法论问题。 相似文献
425.
介绍了县级农业气象常规业务软件的总体设计思路及具体功能模块的实现方法,并对现行的业务运作模式进行了思考。 相似文献
426.
A key part of slope design is the review of past examples of slopes in similar ground conditions. This paper details the development of the SlopeSafe computer program which uses case-based reasoning to formalise this process. The program, written in Visual Basic, draws on a case-base of nearly 3000 case histories of successful and failed slopes to give an indication of the likely success of a proposed slope by matching its geometry and ground conditions to the slopes held in the case-base. XML (Extensible Markup Language) has been used to store the data and a specific set of tags has been defined to provide a standard way of storing slope information. The system has been identified by practising engineers as having the potential to be a very useful design tool. 相似文献
427.
An impervious surface cover is continuously spreading over the Wu-Tu upstream watershed due to the concentrated population
and raised economical demands, while that area also frequently suffers from heavy storms or typhoons during the summer season.
The increased flood volume due to this extended imperviousness causes a greater potential hazard than that of the past. In
order to evaluate the urbanized impacts on the watershed, a set of methods were used to estimate the changes of the watershed
storage. This research chose 51 observed events from three raingauges on the Wu-Tu upstream watershed, Taiwan, to study the
volume characteristic of abstracted rainwater. In the study, the block Kriging method was used to estimate the area rainfall
and the hourly excess was derived through the non-linear programing (NLP). A total of 40 samples were calibrated through the
hydrological model and the Soil Conservation Service (SCS) model using the optimum seeking method in order to search out and
establish the best parameters that illustrate the hydrological and geomorphic conditions at that time. Eleven cases were used
to examine the established relationship of the parameters and the impervious coverings. A design storm approach was used to
view the changes of the volume for various scale storms/typhoons because of the different degrees of urbanization. Then, a
diagram was designed to show the relationships that exist among the runoff coefficient, return period, and impervious surface.
The satisfactory results show that storage capability of rainwater for various scale storms on the Wu-Tu watershed would be
respectively reduced about 42–156 cms in different decrements up to now. 相似文献
428.
With increasing availability of good directional data, provision of directional estimates of extreme significant wave heights, in addition to the omni-directional estimates, is more common. However, interpretation of directional together with omni-directional design criteria is subject to inconsistency, even in design guidelines. In particular, omni-directional criteria are usually estimated ignoring directional effects. In this article, for data which exhibit directional effects, we show that a directional extreme value model generally explains the observed variation significantly better than a model which ignores directionality, and that omni-directional criteria developed from a directional model are different from those generated when directionality is not accounted for. We also show that omni-directional criteria derived from a directional model are more accurate and should be preferred in general over those based on models which ignore directional effects. We recommend use of directional extreme value models for estimation of both directional and omni-directional design criteria in future, when good directional data are available. If effects of other covariates (e.g. time or space) are suspected, we similarly recommend use of extreme value models which adequately capture sources of covariate variability for all design analysis. 相似文献
429.
Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings 总被引:1,自引:0,他引:1
Following several damaging earthquakes in China,research has been devoted to find the causes of the collapse of reinforced concrete(RC) building sand studying the vulnerability of existing buildings.The Chinese Code for Seismic Design of Buildings(CCSDB) has evolved over time,however,there is still reported earthquake induced damage of newly designed RC buildings.Thus,to investigate modern Chinese seismic design code,three low-,mid-and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model(PSDM).The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center.Finally,the PSDM was used to generate fragility curves for immediate occupancy,significant damage,and collapse prevention damage levels.Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level. 相似文献
430.
基于Pro/E的PDC钻头参数化设计 总被引:1,自引:0,他引:1
基于Pro/E (Pro/ENGINEER)的二次开发平台,以煤炭系统常用的胎体式内凹型PDC钻头为例,在系统分析钻头结构特点和主要参数相关性的基础上,建立了钻头结构设计各参数相关性技术体系实体参数化设计模型。通过设计Φ65 mm胎体式内凹PDC钻头,验证了该模型能够快速、准确地利用参数变化完成钻头体的三维及二维结构图设计,从而大大提高了设计效率和质量,为钻头参数化设计提供了参考。 相似文献