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排序方式: 共有2768条查询结果,搜索用时 281 毫秒
991.
Wang Xiaoqing Wang Long Zhang Xihai Ding Xiang Qiu Hu Dong Yanfang DouAixia Zhang Feiyu Liu Zaitao 《中国地震研究》2009,23(4):392-401
The fast developing remote sensing techniques play an increasingly important role in earthquake emergency response, disaster survey and loss estimation. As there is a lack of quantitative studies on seismic damage based on remote sensing, its practicality in seismic disaster management has usually been questioned. The paper introduces the essential quantitative study idea, the concept of the remote sensing seismic damage index (DRS_I RS) and analysis models, demonstrates the seismic damage indices (DG_IC) of buildings obtained from ground surveying and its quantitative relation to DRS_I RS in Dujiangyan city, Sichuan Province, which was destroyed by the 2008 Wenchuan earthquake with M_S8.0. The primary results show that an obvious relationship exists between the DRS_I RS of buildings obtained from the high resolution satellite or aerial remote sensing images and DG_I C or the building collapse ratio obtained through ground survey, which suggests that the quantitative study on seismic damage based on remote sensing will provide an effective method for seismic damage survey and loss estimation. 相似文献
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Ocean-color remote sensing has been used as a tool to detect phytoplankton size classes (PSCs). In this study, a three-component model of PSC was reparameterized using seven years of pigment measurements acquired in the South China Sea (SCS). The model was then used to infer PSC in a cyclonic eddy which was observed west of Luzon Island from SeaWiFS chlorophyll-a (chla) and sea-surface height anomaly (SSHA) products. Enhanced productivity and a shift in the PSC were observed, which were likely due to upwelling of nutrient-rich water into the euphotic zone. The supply of nutrients promoted the growth of larger cells (micro- and nanoplankton), and the PSC shifted to greater sizes. However, the picoplankton were still important and contributed ∼48% to total chla concentration. In addition, PSC time series revealed a lag period of about three weeks between maximum eddy intensity and maximum chlorophyll, which may have been related to phytoplankton growth rate and duration of eddy intensity. 相似文献
996.
Wen-Yi CHANG Jihn-Sung LAI Teng-Yi YU Franco LIN Lung-Cheng LEE Whey-Fone TSAI Chin-Hsiung LOH 《国际泥沙研究》2014,29(2):269-277
A scour monitoring system with a micro camera tracking the bed-level images is proposed in this study.Two image recognition algorithms have been developed to support the bed-level image tracking approach.Through the laboratory experiments of pier scour,this study demonstrates that the proposed system is able to accurately monitor the scour-depth evolution in real time.In addition,five commonly-used temporal scour models are employed to simulate scour-depth evolution and their results are compared with monitoring data.In general,the results indicate that the proposed scour monitoring system has the potential for further applications in the field. 相似文献
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精确估算地表蒸散一直是地球系统科学中的难点问题。经典的蒸散模型大多建立在水汽输送及能量平衡约束等基础上,相关的基础理论研究进展缓慢。最大熵增地表蒸散(E-MEP)模型是在综合借鉴贝叶斯概率论、信息熵概念、非平衡态热力学理论和大气边界层湍流相似性理论的基础上,建立的全新地表蒸散理论框架,克服了经典模型的主要缺陷,包括:离散梯度模型不满足能量守恒条件,Penman模型针对饱和土壤,Penman-Monteith模型需要率定经验参数等。E-MEP模型具有3个显著特点:①同时给出地表(包括水面、雪面和冰面)蒸散量、感热通量和介质表面热通量,且在所有时间空间尺度上满足能量平衡方程;②模型公式中没有可调经验参数,不依赖于温度梯度和水汽梯度变量,不需要输入风速和表面粗糙度;③适用于任何土壤含水量和植被覆盖条件。由于E-MEP模型建立在坚实的数学物理基础上,并具有解析表达式,简单易用,其输入变量和模型参数少于传统蒸散模型使用。地表辐射、表面温度、表面比湿等模型输入变量易于实地观测获取,且可通过遥感反演获得。检验分析表明,E-MEP模型优于Penman和Penman-Monteith等传统蒸散模型。这一全新的地表蒸散模型已被用于大尺度地表水热的遥感反演和过程监测,并用于改进气候模式的参数化方案。 相似文献
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The aim of this study was to determine land use changes in Datong basin using multitemporal Landsat data for the period of
1977–2006. Four dates of Landsat images from 1977, 1990, 2000, and 2006 were selected to classify the study area. Based on
the supervised classification method of maximum likelihood algorithm, images were classified into six classes: water, urban,
forest, agriculture, wetland, and barren land. A multidate postclassification comparison change detection algorithm was used
to determine changes in land use in four intervals. It is found that (1) urban land area increased 213% due to urbanization
that resulted from rapid increase of urban population and high-speed economic development, (2) agriculture area increased
34.0% due to land reclamation that resulted from rapid increase of rural population and improvement of irrigation capacity,
(3) forest area decreased 20.9% due to deforestation for urban area and agricultural use, (4) barren land area decreased 78.2%
due to cultivation for agricultural use, and (5) water and wetland decreased 39.1 and 67.1%, respectively, due to exploitation
of surface water and decrease of recharge from groundwater to surface water that resulted from over exploitation of groundwater. 相似文献