全文获取类型
收费全文 | 1779篇 |
免费 | 322篇 |
国内免费 | 432篇 |
专业分类
测绘学 | 241篇 |
大气科学 | 365篇 |
地球物理 | 360篇 |
地质学 | 915篇 |
海洋学 | 186篇 |
天文学 | 64篇 |
综合类 | 182篇 |
自然地理 | 220篇 |
出版年
2024年 | 10篇 |
2023年 | 37篇 |
2022年 | 87篇 |
2021年 | 108篇 |
2020年 | 82篇 |
2019年 | 87篇 |
2018年 | 111篇 |
2017年 | 99篇 |
2016年 | 94篇 |
2015年 | 94篇 |
2014年 | 101篇 |
2013年 | 108篇 |
2012年 | 96篇 |
2011年 | 94篇 |
2010年 | 103篇 |
2009年 | 78篇 |
2008年 | 75篇 |
2007年 | 77篇 |
2006年 | 77篇 |
2005年 | 69篇 |
2004年 | 58篇 |
2003年 | 43篇 |
2002年 | 58篇 |
2001年 | 55篇 |
2000年 | 52篇 |
1999年 | 97篇 |
1998年 | 74篇 |
1997年 | 85篇 |
1996年 | 59篇 |
1995年 | 40篇 |
1994年 | 35篇 |
1993年 | 46篇 |
1992年 | 35篇 |
1991年 | 28篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1958年 | 2篇 |
排序方式: 共有2533条查询结果,搜索用时 125 毫秒
151.
Decreasing Reference Evapotranspiration in a Warming Climate—A Case of Changjiang (Yangtze) River Catchment During 1970–2000 总被引:1,自引:0,他引:1
This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during 1970–2000 in the Yangtze River catchment. Relative contributions of the four meteorological variables to changes in the reference evapotranspiration are quantified. The results show that both the reference evapotranspiration and the pan evaporation have significant decreasing trends in the upper, the middle as well as in the whole Changjiang (Yangtze) River catchment at the 5% significance level, while the air temperature shows a significant increasing trend. The decreasing trend detected in the reference evapotranspiration can be attributed to the significant decreasing trends in the net radiation and the wind speed. 相似文献
152.
龚朝东 《高原山地气象研究》2006,26(2)
随着用户的增多,MOMINO邮件服务器上的硬盘空间越来越少,如果不增加硬盘空间,将会严重影响到系统的运行,甚至死机.一个解决方案是:为服务器新增一个大硬盘,将数据库文件移到新硬盘上.如何以最小的代价、最快的速度、尽量不影响用户的正常使用来完成此项工作呢?通过查询相关资料,并做了实验,发现有两种方法相对简单. 相似文献
153.
Collision leading to multiple-stage large-scale extrusion in the Qinling orogen: Insights from the Mianlue suture 总被引:10,自引:5,他引:10
Sanzhong Li Timothy M. Kusky Lu Wang Guowei Zhang Shaocong Lai Xiaochun Liu Shuwen Dong Guochun Zhao 《Gondwana Research》2007,12(1-2):121
The geologic framework of the Phanerozoic Qinling–Dabie orogen was built up through two major suturing events of three blocks. From north to south these include the North China craton (including the north Qinling block), the Qinling–Dabie microblock, and the South China craton (including the Bikou block), separated by the Shangdan and Mianlue sutures. The Mianlue suture zone contains evidence for Mesozoic extrusion tectonics in the form of major strike–slip border faults surrounding basement blocks, a Late Paleozoic ophiolite and a ca. 240–200 Ma thrust belt that reformed by 200–150 Ma thrusts during A-type (intracontinental) subduction. The regional map pattern shows that the blocks are surrounded by complexly deformed Devonian to Early Triassic metasandstones and metapelites, forming a regional-scale block-in-matrix mélange fabric. Five distinct tectonic units have been recognized in the belt: (1) basement blocks including two types of Precambrian basement, crystalline and transitional; (2) continental margin slices including Early Paleozoic strata, and Late Paleozoic fluviodeltaic sedimentary rocks, proximal and distal fan clastics, reflecting the development of a north-facing rift margin on the edge of the South China plate; (3) out of sequence oceanic crustal slices including strongly deformed postrift, deep-water sedimentary rocks, sheeted dikes, basalts, and mafic–ultramafic cumulates of a Late Paleozoic ophiolite suite, developing independent of the rift margin in a separate basin; (4) out-of-sequence island-arc slices; (5) accretionary wedge slices. All the tectonic units were deformed during three geometrically distinct deformation episodes (D1, D2 and D3 during 240–200 Ma). Units 2–4 involved southward thrusting and vertical then southward extrusion of about 20 km of horizontal displacement above the autochthonous basement during the D1 episode. Thrust slices 20 km south of the Mianlue suture are related to this vertical extrusion due to the same rock assemblages, ages and kinematics. The D2 and D3 episodes folded all the units in a thick-skinned style about east–west (D2) and west–northwest (D3) axes in the Mianlue suture zone. An early foreland propagating sequence of accretion of Late Paleozoic rocks deposited above the Yangtze craton is not involved in D1 deformation but is temporally equivalent to the D2 and D3 deformation in the Mianlue suture. Two stages of strike–slip faulting mainly occurred at the end of D2 and D3, respectively. During D2 deformation, the Bikou block was obliquely indented to the ESE into the Mianlue suture, rather than being thrust over the Mianlue suture from the north as a part of the Qinling–Dabie microblock. During D3 deformation, however, the Bikou block was bounded by the south boundary fault of the Mianlue suture, and the Yangpingguan fault on the south. These faults are coeval strike–slip faults, but of opposite senses, and accommodated minor southwestward extrusion of the Bikou block into Songpan–Ganze orogen. The other basement blocks north of the Mianlue suture were extruded eastward by about 20 km of lateral displacement, based on the offset of the Wudang dome, during the D3 episode due to the northeastward indentation of the Hannan complex of the South China craton. Post-D3 emplacement of granite, cutting across the strike–slip faults such as the Mianlue suture, provides a minimum age of 200 Ma for D3 deformation. Therefore, based on insights from the evolution of the Mianlue suture, the D2 and D3 episodes in the Mianlue suture and its neighbors are not responsible for and associated with the two-stage extrusion of the Dabie UHP-HP terranes from the Foping dome to the present erosional surface (more than 350 km). 相似文献
154.
WANG Yandong GONG Jianya WU Xiaohuang 《地球空间信息科学学报》2007,10(3):204-207
In GIS field, great varieties of information from different domains are involved in order to solve ac- tual problems. But usually spatial information is stored in diverse spatial databases, manipulated by different GIS platforms. Semantic heterogeneity is caused due to the distinctions of conception explanations among various GIS implements. It will result in the information obtaining and understanding gaps for spatial data sharing and usage. An ontology-based model for spatial information semantic interoperability is put forward after the comprehensive review of progress in ontology theory, methodology and application research in GIS domain. 相似文献
155.
本文提出一种基于小面元相对配准的正射影像快速更新方法,该方法不涉及常规摄影测量的处理方法,而是直接利用新获取的卫星遥感影像和原始正射影像进行高精度小面元相对配准,然后将卫星遥感影像纠正到原始正射影像参考坐标系,进而实现正射影像的快速更新。 相似文献
156.
本文阐述了航测法成图制作1:1万地形数据工作过程中,采用全数字摄影测量工作站对地物进行室内判调“先内后外”的作业方法,并通过对获取的成果与常规方法的对比,证明此法在实际生产中具应用价值。 相似文献
157.
158.
159.
凹凸棒石粘土吸附铀的性能研究及应用 总被引:34,自引:2,他引:32
本文研究了凹凸棒石粘土吸铀的酸度,吸附速率、肿附反应热焓吸附容量等性能,确定了吸附铀的最佳条件,并采用动态法片处理了含铀废水,效果良好,钱的去除率在99.95%以上,排放液中的铀的残余浓度达到国家规定的0.05mg/L排放标准。 相似文献
160.