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121.
Pathways of mesoscale variability in the South China Sea 总被引:5,自引:0,他引:5
The propagation of oceanic mesoscale signals in the South China Sea (SCS) is mapped from satellite altimetric observations
and an eddy-resolving global ocean model by using the maximum cross-correlation (MCC) method. Significant mesoscale signals
propagate along two major bands of high variability. The northern band is located west of the Luzon Strait, characterized
by southwestward eddy propagation. Although eddies are the most active in winter, their southwestward migrations, steered
by bathymetry, occur throughout the year. Advection by the mean flow plays a secondary role in modulating the propagating
speed. The southern eddy band lies in the southwest part of the SCS deep basin and is oriented in an approximately meridional
direction. Mesoscale variability propagates southward along the band in autumn. This southward eddy pathway could not be explained
by mean flow advection and is likely related to eddy detachments from the western boundary current due to nonlinear effects.
Our mapping of eddy propagation velocities provides important information for further understanding eddy dynamics in the SCS. 相似文献
122.
<正>A theoretical model of a friction pendulum system(FPS) is introduced to examine its application for the seismic isolation of spatial lattice shell structures.An equation of motion of the lattice shell with FPS bearings is developed.Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS.The influence of frictional coefficients and radius of the FPS on seismic performance are discussed.Based on the study,some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS. 相似文献
123.
124.
我国地震防灾减灾科普教育的瓶颈及对策分析 总被引:1,自引:0,他引:1
地震灾害已经成为影响我国经济发展和社会安全的重要因素,我国防震减灾事业存在很多难以快速解决的问题,因此在当前的基本国情下,加强地震防灾减灾科普教育,提高群众防灾避险意识和能力,对缓解地震中人员伤亡有着非常重要的作用。本文就地震防灾减灾工作中,地震防灾减灾科普教育的重要性,以及现阶段我国地震防灾减灾科普教育存在的问题,进行了分析和探讨;并针对上述问题,提出了相应的对策。 相似文献
125.
Paleoproterozoic supracrustal materials have been widely identified in North China Craton, such as the Liaohe-, Hutuo-and Lyuliang groups. The Liaohe Group in the eastern part of the North China Craton is dominated by deformed and metamorphosed sedimentary and volcanic successions. Compared with that of the coeval volcanic rocks, geochemistry of the sedimentary rocks from the Liaohe Group has rarely been studied in detail, which can possibly provide information on the paleoclimate and provenance. The authors analyzed the whole-rock and detrital zircon geochemistry of sedimentary rocks from the Liaohe Group against a uniform process and proposed their different ways of paleoweathering of the lower and upper formations. That is to say, although the lower and upper formations within the Liaohe Group might be derived from the similar source composition in a tectonically active setting, the paleoclimate that they experienced was not exactly the same. The predominant derivations are the Paleoproterozoic granitoids and basalts within the Liaohe Group, with minor input of Archean continental crust. This study highlights the contributions of the Paleoproterozoic mafic sources, which has been generally overlooked in the previous researches. 相似文献
126.
The Wenchuan Earthquake (May 12, 2008), Sichuan Province,China, and resulting geohazards 总被引:19,自引:5,他引:14
Peng Cui Xiao-Qing Chen Ying-Yan Zhu Feng-Huan Su Fang-Qiang Wei Yong-Shun Han Hong-Jiang Liu Jian-Qi Zhuang 《Natural Hazards》2011,56(1):19-36
On Monday, May 12, 2008, a devastating mega-earthquake of magnitude 8.0 struck the Wenchuan area, northwestern Sichuan Province,
China. The focal mechanism of the earthquake was successive massive rock fracturing 15 km in depth at Yingxiu. Seismic analysis
confirms that the major shock occurred on the Beichuan–Yingxiu Fault and that aftershocks rapidly extended in a straight northeast–southeast
direction along the Longmenshan Fault zone. Fatalities approaching a total of 15,000 occurred, with a significant number resulting
from four types of seismically triggered geohazards—rock avalanches and landslides, landslide-dammed lakes (“earthquake lakes”),
and debris flows. China Geological Survey has identified 4,970 potentially risky sites, 1,701 landslides, 1,844 rock avalanches,
515 debris flows, and 1,093 unstable slopes. Rock avalanches and landslides caused many fatalities directly and disrupted
the transportation system, extensively disrupting rescue efforts and thereby causing additional fatalities. Landslide-dammed
lakes not only flooded human habitats in upstream areas but also posed threats to potentially inundated downstream areas with
large populations. Debris flows become the most remarkable geohazards featured by increasing number, high frequency, and low
triggering rainfall. Earthquake-triggered geohazards sequentially induced and transformed to additional hazards. For example,
debris flows occurred on rock avalanches and landslides, followed by landslide-dammed lakes, and then by additional debris
flows and breakouts of the landslide-dammed lakes and downstream flooding. Earthquake-induced geohazards occurred mainly along
the fault zone and decreased sharply with distance from the fault. It can be anticipated that post-earthquake geohazards,
particularly for debris flows, will continue for 5–10 years and even for as long as 20 years. An integrated strategy of continuing
emergency response and economic reconstruction is required. The lesson from Wenchuan Earthquake is that the resulted geohazards
may appear in large number in active fault regions. A plan for geohazard prevention in the earthquake-active mountainous areas
is needed in advance. 相似文献
127.
128.
由于良好的疲劳特性,自由站立式立管(FSHR)正广泛应用于深海油气田的开发当中。首先根据设计参数建立FSHR详细的有限元模型,然后利用谱分析方法对FSHR进行总体运动疲劳分析,以确定FSHR总体设计参数是否满足运动疲劳要求。最后对工作于相同环境下的钢悬链立管(SCR)进行总体运动疲劳分析,探讨哪种立管系统的疲劳性能更为优良。计算结果表明FSHR系统中刚性主管最大运动疲劳损伤出现在刚性主管顶部,FSHR总体设计参数满足规范要求;FSHR总体运动疲劳寿命要远大于SCR,体现了FSHR系统对浮体运动与刚性主管之间具有良好的解耦作用。 相似文献
129.
130.
Spatial distribution of surface soil water content under different vegetation types in northwest Guangxi, China 总被引:3,自引:1,他引:2
Wanxia Peng Tongqing Song Fuping Zeng Kelin Wang Hu Du Shiyang Lu 《Environmental Earth Sciences》2013,69(8):2699-2708
Geostatistical and statistical analyses were combined to examine the spatial distribution of soil water content under four vegetation types during the dry season, in the peak-cluster depression in the karst region in northwest Guangxi, southwest China. The soil water content significantly increased from farmland to plantation, secondary forest, and primary forest; whereas the variation coefficients, the sill (C 0+C), and total spatial variance increased, although the range decreased. The spatial distribution of soil water content in the different vegetation types had a high spatial autocorrelation. Different models produced a best fit for the semivariograms of the four vegetation types. Elevation and slope position were the primary factors influencing the spatial distribution of soil water content, with other key factors differing between the four vegetation types. Moreover, even though different specific factors influenced soil water content in the four vegetation types, the correlations and degrees of associations between the soil water content and these various factors differed. Therefore, the corresponding strategies for rational usage and management of water resources should be different for the four vegetation types in this region. 相似文献