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针对传统的单动双管取心器存在的内外管同心度差、轴承容易损坏、没有滤浆沉砂装置、双管间隙容易堵塞、取心效率低等问题,研制出DJ型单动双管取心器。该取心器主要由滤浆沉砂装置、密封单动装置、内管(半合管)调节组件和卡心装置组成,具有同心度高、密封性好、滤液及水路设计合理、取心管长度大、可减少钻进回次、提高取心效率等特点。现场应用表明:该取心器取心效果好,使用寿命是传统取心器的2倍以上。 相似文献
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The microstructure of a stably stratified boundary layer, with a significant low-level nocturnal jet, is investigated based
on observations from the CASES-99 campaign in Kansas, U.S.A. The reported, high-resolution vertical profiles of the temperature,
wind speed, wind direction, pressure, and the turbulent dissipation rate, were collected under nocturnal conditions on October
14, 1999, using the CIRES Tethered Lifting System. Two methods for evaluating instantaneous (1-sec) background profiles are
applied to the raw data. The background potential temperature is calculated using the “bubble sort” algorithm to produce a
monotonically increasing potential temperature with increasing height. Other scalar quantities are smoothed using a running
vertical average. The behaviour of background flow, buoyant overturns, turbulent fluctuations, and their respective histograms
are presented. Ratios of the considered length scales and the Ozmidov scale are nearly constant with height, a fact that can
be applied in practice for estimating instantaneous profiles of the dissipation rate. 相似文献
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两相流过泵回流试验是模拟水力提升系统紧急停泵情况下垂直管道中颗粒运动状态,紧急停泵时,可能会出现堵管、难于输送等现象。为提高管道水力输送安全性,采用三种不同的模拟结核颗粒(粒径分别为d≤10 mm,d≤20 mm,d≤50 mm),两种不同浓度(CV=5%,CV=8%),在两级泵额定流量Q=420 m3/h条件下进行了过泵回流试验,分析了试验结果,从多个方面总结了堵管原因。认为实际工程中应该严格控制颗粒上限粒径,采用合适的颗粒级配,并对管道定期进行清洗,尽量减少管道的大角度转弯和断面突变。 相似文献
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自适应提升形态小波将多分辨率分解和图像空域中目标的几何结构和局部特征相结合,可以满足特定图像处理任务的需要。本文针对甲藻类细胞显微图像边缘模糊、对比度低等不利于甲沟特征提取的困难,构造1种边缘保留自适应提升形态小波。该小波将图像的边缘作为重要的局部特征,更新提升根据是否是边缘像素选择保留、锐化滤波或平滑滤波,使得分解后的近似图像中,图像边缘得以保留,而灰度变化缓慢的区域得到了平滑。实验结果证明:甲藻细胞经边缘保留自适应提升形态小波分解后的近似图像,在一定程度上突出了目标边界,较之原始图像,更有利于甲沟特征的提取。 相似文献
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Depressions in landscapes function as buffers for water and sediment. A landscape with depressions has less runoff, less erosion and more sedimentation than that without depressions. Sinks in digital elevation models (DEMs) can be considered the real features that represent depressions in actual landscapes or spurious features that result from errors in DEM creation. In many hydrological and erosion models, all sinks are considered as spurious features and, as a result, these models do not deal with the sinks that represent real depressions. Consequently, the surface runoff and erosion are overestimated due to removing the depressions. Aiming at this problem, this paper presents a new method, which deal with the sinks that represent real depressions. The drainage network is extracted without changing the original DEM. The method includes four steps: detecting pits, detecting depressions, merging depressions, and extracting drainage network. Because the elevations of grid cells are not changed, the method can also avoid producing new fiat areas, which are always produced by the conventional filling methods. The proposed method was applied to the Xihanshui River basin, the upper reach of the Jialingjiang River basin, China, to automatically extract the drainage network based on DEM. The extracted drainage network agrees well with the reality and can be used for further hydrologic analysis and erosion estimation. 相似文献
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针对金塘大桥3号主桥墩ZK8号钻孔烧钻断杆事故及事故处理不当发生的卡杆二次事故,认真分析了事故原因,制订了严密的钻具打捞方案,成功打捞了孔内钻具,为后续钻孔灌注桩的施工排除了障碍。介绍了事故状况及处理技术。 相似文献
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