全文获取类型
收费全文 | 2763篇 |
免费 | 829篇 |
国内免费 | 1310篇 |
专业分类
测绘学 | 389篇 |
大气科学 | 2172篇 |
地球物理 | 704篇 |
地质学 | 922篇 |
海洋学 | 343篇 |
天文学 | 58篇 |
综合类 | 172篇 |
自然地理 | 142篇 |
出版年
2024年 | 25篇 |
2023年 | 78篇 |
2022年 | 105篇 |
2021年 | 149篇 |
2020年 | 157篇 |
2019年 | 212篇 |
2018年 | 138篇 |
2017年 | 174篇 |
2016年 | 145篇 |
2015年 | 183篇 |
2014年 | 260篇 |
2013年 | 240篇 |
2012年 | 277篇 |
2011年 | 244篇 |
2010年 | 196篇 |
2009年 | 261篇 |
2008年 | 207篇 |
2007年 | 273篇 |
2006年 | 262篇 |
2005年 | 178篇 |
2004年 | 182篇 |
2003年 | 139篇 |
2002年 | 97篇 |
2001年 | 109篇 |
2000年 | 84篇 |
1999年 | 79篇 |
1998年 | 66篇 |
1997年 | 72篇 |
1996年 | 62篇 |
1995年 | 45篇 |
1994年 | 40篇 |
1993年 | 50篇 |
1992年 | 24篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1954年 | 3篇 |
排序方式: 共有4902条查询结果,搜索用时 15 毫秒
991.
ATMOSPHERIC PROFILER AND PRELIMINARY INVESTIGATION ON THE MONITORING OF DISASTROUS WEATHER
下载免费PDF全文
![点击此处可从《Acta Meteorologica Sinica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Outlined in this paper are main technical specifications of the first profiler developed in China. The profileris composed of a UHF Doppler radar for wind measurement and a microwave radiometer, and preliminarilyapplied in the Beijing-Tianjin-Hebei base of monitoring disastrous weather in 1989—1990. This paper presentsthe preliminary and valuable results obtained by the instrument in the monitoring of severe storm generating andevolution, showing the potential of this instrument in weather monitoring. 相似文献
992.
STUDY ON APPLICATIONS OF C-BAND DUAL LINEAR POLARIZATION RADAR IN METEOROLOGY 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Acta Meteorologica Sinica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Theoretical study and development of a dual linear polarization weather radar in China are briefly presented.Also discussed are the potential uses of the new radar system in improving the accuracy of areal rainfall measure-ments and analysing the spacial structure of storms and distribution of hydrometecrs in clouds based on theradar observational data from the field experimcnts during the summers of 1987—1989. The results indicatethat a C-band dual polarization weather radar, after considering the microwave attenuation correction, may beemployed to quantitatively measure rainfall and to monitor heavy rain and flood events and becomes an impor-rant means to study storm structure. 相似文献
993.
994.
995.
996.
用C波段双线偏振雷达研究冰雹云 总被引:18,自引:1,他引:18
本文计算了不同相态、不同形状的降水粒子对5.6cm,10.7cm雷达波的散射特性,并利用降水粒子散射特性及云雨雷达回波的Z_(DR)特征并结合地面降雹情况,分析并解释了1990年8月9日和8月30日甘肃省平凉两次雹暴过程的雷达RHI资料.我们推测:Z_(DR)值为负值的区域相应于降雹区,ZDR负值与大扁冰雹和小锥状冰雹关系密切;而雨区Z_(DR)具有较大正值,雨区大于5dB的Z_(DR)由直径D>0.5cm的雨滴所致.利用冰雹区和雨区Z_(DR)信息的不同可能识别降水粒子的相态.C波段双线偏振雷达和10cm波长雷达相比有独到之处:雨区Z_(DR)值较大,而冰雹区Z_(DR)值又较小,这更有利于研究云雨相态和空间结构.可以预期双线偏振雷达对防雹工作及云物理研究工作是有很大帮助的. 相似文献
997.
998.
在双线偏振雷达试制过程中,其视频积分处理器(DVIP)不同于常规雷达的DVIP。即将常规雷达峰值采样的DVIP改为具有距离、方位双重积分的多点采样智能化的DVIP,以减小脉动,提高被测对象的稳定性。本文介绍了双线偏振DVIP的组成方式、特点及工作原理。 相似文献
999.
1000.
B. R. Arora 《Journal of Earth System Science》1990,99(4):693-716
Significant results from several array of magnetometers deployed in India to probe deep geoelectrical structures of the crust
and the upper mantle are reviewed in this paper. Emphasis is on critical appraisal of earlier results so that the article
summarizes what has been done so far and what caution is to be taken on future work.
Two large-scale arrays over northwest and peninsular India during 1979–80, have been followed up with six more linear or two-dimensional
arrays over different parts of the country.
“Trans-Himalayan” conductor aligned along the strike of Aravalli range, delineated by arrays over northwest India, essentially
represents one of the major continental induction anomalies mapped by electromagnetic methods. Efforts for quantifying the
induction effects through numerical models are shown to be constrained due to the large inter-station spacing, lack of information
on the regional background conductivity distribution and the non-inclusion of the frequency dependence of induction effects.
A more comprehensive modelling, not biased by these factors, enables approximating the Trans-Himalayan conductor as an asymmetric
domal upwarp in the middle and lower crust located between Delhi-Hardwar ridge and Moradabad fault. Numerical modelling results
for southern peninsular, despite the constraints, indicate that the strong and complex induction pattern can be adequately
attributed to the combination of conductors connected with triple junction between Indo-Ceylon Graben, Comorin ridge and the
west coast rifting.
Induction features derived from the Valsad array, operated over basalt-covered region of western India, demarcate an enhanced
conducting zone beneath Plume-associated triple junction in the Gulf of Cambay, apart from characterizing the presently active
seismic zone as a resistive block. 相似文献