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As a connection region between Arctic and North Atlantic oceans, the Nordic seas play a critical role in global climate system. The density waters overflow through Greenland-Scotland Ridge from the Nordic seas, as the main source of the North Atlantic Deep Water (NADW), which plays a key role in global ocean conveyor. The causes and processes, which give some instruction of the overflow variation are still uncertain. Based on a review of current and historical research results of modern Nordic seas overflows, hydrological and flux characteristics and variation features of overflows through three channels, which are Faroe-Shetland Channel, Iceland-Faroe Ridge and Denmark Strait, from Nordic sea were addressed separately. The origins of overflows water and factors and physical processes that may have impact on the three overflows were also analyzed separately. Intense mixing in overflow through Faroe-Shetland Channel was discussed. At last, the changing mechanism of the whole overflow from Nordic seas and relationships among overflows through different channels were summed up. The aim of this paper is to give some instructions and research directions to the internal readers. 相似文献
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Acta Geotechnica - In situ monitoring provides valuable information to update the predictions of the embankment settlement on soft soils. Observational data obtained at different monitoring moments... 相似文献
76.
为提高GNSS高程时间序列的去噪效果,以仿真信号和拉萨站2000~2020年高程时间序列为例,采用自适应噪声完备集合经验模态分解(complete ensemble empirical mode decomposition with adaptive noise,CEEMDAN)方法将信号分解成若干个特征模态函数(intrinsic mode function,IMF),对每个IMF分量进行小波包多阈值分解,依据不同节点能量占IMF总能量百分比选择不同的阈值准则,将降噪后的节点重构得到降噪后的IMF分量,进而得到降噪后的时间序列。利用信噪比、均方根误差等指标对比分析本文方法、EMD、CEEMDAN、小波去噪和小波包多阈值去噪等5种方法的去噪效果。结果表明,本文方法效果最优。 相似文献
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Through the analysis of the faults and their internal structure in Zhu I Depression, it is found that the internal structure of the late fault is obviously segmented vertically. It develops unitary structure(simple fault plane) in shallow layers, binary structure(induced fracture zone in hanging wall and sliding fracture zone in footwall) in middle, layers and ternary structure(induced fracture zone in hanging wall and sliding fracture zone in middle,and induced fracture zone in footwall) in deep layers. Because the induced fracture zone is a high porosity and permeability zone, and the sliding fracture zone is a low porosity and ultra-low permeability zone, the late fault in middle layers has the character of "transporting while sealing". The late fault can transport hydrocarbon by its induced fracture zone in the side of the hanging wall and seal hydrocarbon by its sliding fracture zone in the side of the footwall. In deep layers, the late fault has the character of "dual-transportation", induced fracture zones in both sides of hanging wall and footwall can transport hydrocarbon. The early fault that only developed in the deep layers is presumed to be unitary structure, which plays a completely sealing role in the process of hydrocarbon migration and accumulation due to inactivity during the hydrocarbon filling period. Controlled by hydrocarbon source, early/late faults, sand bodies and traps, two reservoir-forming models of "inverted L" and "stereo-spiral"can be proposed in middle layers, while two reservoir-forming models of "cross fault" and "lateral fault sealing"are developed in the deep layers of Zhu I Depression. 相似文献
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单一基元分类方法难以全面描述复杂的点云场景,采用多基元进行分类成为一种趋势,提出了一种融合点、体素和对象特征的点云分类方法。主要包括4个方面:(1)分别确定各层面分类基元,点基元方面采用最优邻域方法,体素基元方面基于八叉树方法进行体素划分,对象基元方面使用改进的多要素分割方法进行点云分割;(2)提取各基元分类特征,首先提取点基元分类特征并进行局部线性约束编码(Locality-constrained Linear Coding, LLC),然后以此为基础提取体素基元和对象基元的潜在狄利克雷分布特征(Latent Dirichlet Allocation, LDA)和最大池化特征(Max Pooling, MP);(3)降低分类特征维度,利用随机森林变量重要性算法对分类特征进行筛选与降维;(4)进行点云分类,使用随机森林算法实现点云分类。采用3种不同类型的点云数据进行试验,结果表明融合3种基元特征的分类精度相比于点基元分类分别提升了1.43%、7.02%和2.48%,分类特征降维可以有效降低特征冗余度,分类器分类时间减少约70%;通过与其他算法的对比,新算法分类精度更优,且适用于多种场景... 相似文献
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基于2008—2017年全国自动气象观测站逐旬土壤相对湿度观测数据,综合评估中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)0~20 cm层融合土壤相对湿度产品在中国地区的适用性,评估表明CLDAS土壤相对湿度产品在中国东北、西北、江南大部及华南等地区存在较大系统性误差,总体上适用性较差。为消除CLDAS土壤相对湿度产品的系统性误差,采用回归订正法、7旬滑动平均订正法和临近加权前旬订正法对CLDAS土壤相对湿度产品进行误差订正处理,对订正结果评估发现:订正处理后CLDAS土壤相对湿度产品与站点观测的相关性显著增加,系统偏差基本消除,适用性明显提高,3种订正方法中临近加权前旬订正法的订正效果最优。最后,采用经不同方法订正后的CLDAS土壤相对湿度产品对2017年5月东北—华北地区一次气象干旱个例进行重现,对比验证表明:相对其他两种订正方法,经临近加权前旬订正法处理后的CLDAS土壤相对湿度产品能更为精准地重现2017年5月东北—华北地区气象干旱的落区和强度。 相似文献
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研究结果表明,在混合表面活性剂CTMAB-吐温-60存在下的pH5.7~6.5的缓冲介质中,Sc(Ⅲ)与4,5-二溴苯基荧光酮(DBPF)形成高灵敏的多元配合物,其ε_(590)=2.26×10 ̄5L·mol ̄(-1)·cm ̄(-1),组成比为:Sc:DBPF:CTMAB=1:2:4。采用混合表面活性剂使增溶增敏作用更为显著,并加速了显色反应,增强了配合物的稳定性。而Na_2SO_4的加入能显著地提高体系的灵敏度。Sc量在0~0.36ug/ml范围内遵守比尔定律。方法可直接测定合成混合稀土中的Sc,回收率在98%~105%;结合沉淀分离和PMBP萃取分离,实现了地质试样中痕量Sc的测定。 相似文献