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821.
基于遥感资料的陕北黄土高原植被覆盖率时空特征分析 总被引:1,自引:0,他引:1
选取黄土高原的典型区域--陕北作为监测区域,以MODIS和TM资料作为主要数据源,从可业务化的角度采用植被指数法进行了植被覆盖率的遥感反演,对4种生态气候区植被覆盖率季相变化特征进行了分析,并对陕北生态环境治理前后植被覆盖率的变化进行了对比,结果表明:生态治理后陕北黄土高原的植被覆盖率绝大多数地区都是正增长,各生态气候区植被覆盖状况都有了不同程度的改善,生态治理效果最明显的区域在陕北南部. 相似文献
822.
张兰生 《中国地理科学(英文版)》1992,2(4):312-321
Recent achievements of the research on Chinese environmental evolution are brieny summarized in this paper. Following aspects are touched upon: relationship between Chinese environmental evolution and global change, the influence of the swift uplift of the Qinghai-Xizang Plateau, time sequence and the reconstruction of environment in characteristic stages, trend towards dryness in north and northwestern China, sea level change and regional studies. 相似文献
823.
青藏高原均衡重力异常研究 总被引:1,自引:0,他引:1
根据重力异常图等有关资料,研究了青藏高原均衡重力异常的分布特征与地质构造、地壳新构造运动间的关系,结果表明:(1)高原内各块体的均衡状态并不均一,而且异常幅值大小与地壳的相对隆起或沉降程度相关;(2)高原均衡异常同强地震分布有较密切的联系 相似文献
824.
STREAMFLOW CHARACTERISTICS OF THE EASTERN QINGHAI-XIZANG PLATEAU 总被引:1,自引:0,他引:1
The eastern Qinghai-Xizang (Tibet) Plateau is the headwater area for many large Asian rivers. Permafrost occurs above 4,200 m a.s.l. and glaciers occupy the summits and high valleys of the east-west trending mountain chains. Annual runoff generally increases with precipitation which is augmented southward by the rise in topography. Rainfall, snow melt, glacier melt and groundwater are the primary sources of stream flow, and the presence of permafrost enhances the flashiness of runoff response to rainfall and snowmelt events. Peak flows are concentrated between June and September. And winter is low flow season. Three types of runoff patterns may be distinguished according to their primary sources of water supply: snowmelt and rainfall, glacier melt and snowmelt, and groundwater. Large rivers generally drain more than one environments and their runoff regime reflects an integration of the various flow patterns on the plateau. 相似文献
825.
Zhao Kuiyi 《中国地理科学(英文版)》1997,8(1):44-52
The southern part of the Qinghai-Xizang (Tibet) Plateau and its adjacent area are rich in mire flora. There are 51 families,
101 genera and 220 species. The geographical compositions of this region are very complex, consisting of the following-geographical
elements: tropic-subtropic elements approximating to 8.33% of the entire flora in the region, tropic-temperate elements 22.71%,
temperate elements 43.18%, cosmopolitan elements 9.85%, the Qinghai-Xizang endemic elements 14.39%, north polemountain elements
1.51%. Temperate elements in this region are dominant. The dominant species of mires, Carex lasiocarpa, in this region is also found in northeast China, Finland and North America. The origin of mires of this region is earlier
than northeast China and Finland. This shows that the southern part of the Qinghai-Xizang Plateau and its adjacent areas may
be the centre of the origin and distribution of temperate elements. 相似文献
826.
Based on the analysis of the 1993 and 1995 GPS data acquired from crust movement and deformation monitoring in thc Qinghai-Xizang
Plateau, the following preliminary conclusions could be drawn: the levelly moving rate and direction of the land massifs in
the Qinghai-Xizang Plateau tally with the viewpoint generally held by geologists and geophysicists irr recent years; the accuracy
of monitoring crust movement has reached the world advanced level; the result has provided valuable and reliable information
to the quantitative analysis of the modern crust movement and deformation in the plateau.
Project supported by the Nntional Natural Science Foundation of China. 相似文献
827.
The knowledge of contemporary climatic change over the Qinghai-Xizang (Tibet) Plateau (QXP) has been inadequate for a long
time due to lack of enough observational data. In this paper, on the basis of monthly temperature and precipitation data in
1961–1990 from 48 stations on the QXP, the temperature data are extended backward to 1901 with an empirical orthogonal function
(EOF) method, microscopic characteristics of contemporary climatic change over the QXP are analyzed, and the response of the
plateau climate to global warming is discussed in combination with atmospheric general circulation model (GCM) outputs. The
results show that the plateau climate, as a whole, has been warming since the early part of this century, that the precipitation
has generally been increasing during the recent 30 years, and that these climatic trends seem to be related to the enhanced
green-house effect induced by increasing CO2 concentration in the atmosphere.
This work is supported by the National and CAS (the Chinese Academy of Sciences) Tibet Research Project. 相似文献
828.
829.
地面热源强迫对青藏高原低涡作用的动力学分析 总被引:12,自引:3,他引:12
将一类暖性青藏高原低涡考虑为受加热和摩擦强迫作用并满足热成风平衡的轴对称涡旋系统,给定符合高原地面加热特点的加热分布函数,通过求解简化后的柱坐标系中的涡旋模式,得到了低涡对应的流函数、水平流场、水平散度场和垂直运动场的解析解,分析了地面热源对高原低涡流场结构的作用,给出了高原低涡眼壁内、外侧以及不同高度上的水平流场、水平散度场和垂直流场的结构特征,对影响低涡生成的主要因子进行了讨论。研究结果揭示了地面热源强迫对高原低涡的形成及结构特征的重要作用。 相似文献
830.