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91.
Norman A. Andresen 《Journal of Paleolimnology》2003,30(4):461-464
Image enhancement provides a means to facilitate information transfer without altering the image information. A plug-in for the commonly used image capture and manipulation program Photoshop is discussed as one useful tool. 相似文献
92.
提出以C Builder 6.0为开发平台,以其所提供的TJPEGImage为核心,实现真彩色图像的压缩,为工程实际的应用提供了一种非常实用的压缩手段。该方法减少了大量程序代码的编写工作。实验表明,当综合压缩比设为65时,压缩图像与原图像相比并无明显变化,由此可见,压缩效果令人满意。 相似文献
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The technique of image matching is the basis of image fusion,image mosaic and scene 3D reconstruction.In the paper a novel image registration method based on SUSAN operator is proposed.Firstly,Corner points are extracted by using SUSAN(Smallest Univalue Segment Assimilating Nucleus) operator.Then matched corner points are selected through coarse matching and fine matching.Based on such corner pairs,aerophotos are registered automatically. 相似文献
96.
图像重建算法FBP与OSEM在工业CT应用中的对比研究 总被引:1,自引:0,他引:1
滤波反投影法(FBP)与有序子集最大期望值法(OSEM)是图像重建中最为常用的两种方法,本文研究了这两种重建方法在工业CT中的应用,就不同的探测器数目、不同的旋转投影角度取样数、不同的噪声水平,对两种方法的重建效果进行对比与分析,结果表明在某些条件下迭代法OSEM重建图像质量明显好于解析法FBP。 相似文献
97.
Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Construction and operation of the dam has enhanced the degree to which the first two of these four effects are evident, and has not affected the degree to which the last two effects of sand supply limitation are evident in the Colorado River in Marble and Grand canyons. The first three of the effects involve coupled changes in suspended-sand concentration and grain size that are controlled by changes in the upstream supply of sand. During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase, even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. Also associated with these changes in sand supply are changes in the fraction of the bed that is covered by sand. Thus, suspended-sand concentration in the Colorado River is likely regulated by both changes in the bed-sand grain size and changes in the bed-sand area. A physically based flow and suspended-sediment transport model is developed, tested, and applied to data from the Colorado River to evaluate the relative importance of changes in the bed-sand grain size and changes in the bed-sand area in regulating suspended-sand concentration. Although the model was developed using approximations for steady, uniform flow, and other simplifications that are not met in the Colorado River, the results nevertheless support the idea that changes in bed-sand grain size are much more important than changes in bed-sand area in regulating the concentration of suspended sand. 相似文献
98.
The assessment of grain size distribution and plasticity of loose geological material, during in situ geological investigations, is not obvious. Visual appreciation allows an approximative quantification of the coarse granulometric fractions, but not of the fine ones. Field soils determination methods suggested until now, are visual and tactile tests leading to a very rough estimate, which is only qualitative and not very reproducible. The new proposed field test (GEOLEP method) allows a quick quantification of the fine fraction of loose material. It allows the determination of the sand fraction (fine and medium grained sands) as well as the methylene blue value of the samples. The necessary equipment to perform this test is light and compact and the time needed to analyze one sample is approximately 15 min. Thus it is also possible to carry out numerous measurements in one day. The calibrations were carried out on a selection of 13 natural samples, chosen for their representativeness of the typical alpine quaternary deposits. The results obtained with GEOLEP method are relevant compared with standardized laboratory tests; the obtained correlation indexes are of 73% for the comparison with laboratory stain test results and of 89% with a laboratory method using a similar procedure than the field test. The correlation we performed with Atterberg's limits tests shows that a rough approximation of plasticity index can also be obtained (R2 = 75%). This method thus brings a new tool which should allow taking into account the lithological factor (by some quantitative and representative variables) in a reliable way for the evaluation of landslide hazards. 相似文献
99.
This paper presents the development and utilisation of an automated image processing algorithm for detection and analysis
of grains. Using optical polarising microscopy, a set of colored images are collected from an area on a thin section. A filtering
operation, using rotation of a morphological alternating sequence filter (based on a structuring element), is used to remove
twinning features within individual grains. Filtering is followed by the watershed segmentation technique to determine grain
boundaries. The method is used for the identification of calcite grains in marble and the subsequent analysis of morphological
anisotropy. 相似文献
100.