全文获取类型
收费全文 | 3405篇 |
免费 | 533篇 |
国内免费 | 469篇 |
专业分类
测绘学 | 136篇 |
大气科学 | 606篇 |
地球物理 | 1150篇 |
地质学 | 1777篇 |
海洋学 | 101篇 |
天文学 | 13篇 |
综合类 | 145篇 |
自然地理 | 479篇 |
出版年
2024年 | 27篇 |
2023年 | 59篇 |
2022年 | 104篇 |
2021年 | 138篇 |
2020年 | 121篇 |
2019年 | 115篇 |
2018年 | 116篇 |
2017年 | 138篇 |
2016年 | 141篇 |
2015年 | 129篇 |
2014年 | 167篇 |
2013年 | 225篇 |
2012年 | 168篇 |
2011年 | 165篇 |
2010年 | 172篇 |
2009年 | 224篇 |
2008年 | 257篇 |
2007年 | 240篇 |
2006年 | 218篇 |
2005年 | 194篇 |
2004年 | 181篇 |
2003年 | 162篇 |
2002年 | 126篇 |
2001年 | 113篇 |
2000年 | 123篇 |
1999年 | 99篇 |
1998年 | 78篇 |
1997年 | 61篇 |
1996年 | 75篇 |
1995年 | 62篇 |
1994年 | 39篇 |
1993年 | 40篇 |
1992年 | 46篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 20篇 |
1988年 | 19篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有4407条查询结果,搜索用时 0 毫秒
201.
本文概要介绍长江上游宜宾—宜昌干流两岸山地城镇座落的自然环境,重点论述山地城镇滑坡灾害,最后提出了区域防灾战略的新途迳。 相似文献
202.
Wojciech Stopiński Gienadiy A. Sobolev Aleksandr W. Ponomaryov Vladimir Los 《Pure and Applied Geophysics》1991,136(1):49-58
Making measurements of electric resistivity at 16 s intervals, the authors noticed fast changes of this parameter prior to the occurrence of the main fracture. The changes are superposed on bay pulsations of increasing amplitude and decreasing period. This finding opens prospects for a wider use of an electric resistivity method and proves the high quality of automatic instruments, in particular their high resolution. It also gives evidence for the occurrence of short-period precursors in the fracture zone while the main fracture is being formed. 相似文献
203.
沈建文 《地震学报(英文版)》1994,(Z1)
CumulativefrequencybvaluewithoutupperboundmagnitudeanditsregressiondeterminationJian-WenSHEN(沈建文)(SeismologicalBureauofAnhuiP... 相似文献
204.
通过实地考察、槽探和浅层地震探测等手段以及对地质构造和地下水超采环境的分析,详细地研究了大同铁路分局地裂缝带的三维构造特征,指出现今处于发展中的地裂缝带是由东向西扩展的,扩展速率为260~520m/a,地裂缝带两侧的差异升降运动速率达22.1~24.4mm/a,主地裂缝带的水平拉张速率约1.11~11.6mm/a,垂直错动速率0.2~8.57mm/a,左旋错动速率1.87~3.57mm/a。地裂缝带的活动方式为无震蠕滑型,扩展中的地裂缝是一种无震的地质灾害 相似文献
205.
The Seismic Intensity Zoning Map of China(1990)was based on the probabilistic method of seismic hazard analysis.In compiling the map,the characteristics of inhomogeneity of earthquake distribution both in space and time in China are considered sufficiently,and some necessary modifications in the model of seismic hazard analysis are carried out.Based on the analysis of the seismic activity and seismotectonic environment,26 seismic provinces are divided first as the statistical elements of the seismicity analysis; the seismic potential source areas are then divided in the seismic provinces.The 733 potential source areas with various upper limit magnitudes have been divided in the country.According to the reliable time domain of earthquake data with various magnitude intervals,the b values in magnitude-frequency relationship are calculated in the seismic provinces.According to the analysis of the inhomogeneity of seismicity distribution both in space and time,the annual average occurrence rates of the eart 相似文献
206.
应用考虑震级不确定笥和资料完整性估计地震危险性参数的极大似然法,分别采用1940年和1070年至1993年完整的地震资料,计算了汾渭地震带及陕南地区的地震危险性参数。结果表明:利用近几十年来的完整地震资料结合研究区历史上发生的最大地震,可以得到较为可靠的地震危险性参数;参数敏感性分析表明,完整震级不确定性对β的影响较小;随震级不确定性的增大地震年发生率减小;在资料完整的前提下,震级下限在一定范围内 相似文献
207.
Stefan Keller 《Surveys in Geophysics》1995,16(5-6):661-670
Laboratory simulation of powder snow avalanches serves for the validation of numerical models and as a tool in its own right for consulting and research purposes. Two-phase gravity currents are simulated in water with quartz powder or glass spheres as the particle phase. Particle-phase velocity profiles and particle-phase volume fraction profiles are measured with an ultrasonic device. The experimental setup and the current state of the measurement technique are described and preliminary results are presented. 相似文献
208.
D. Albarello A. Berardi C. Margottini M. Mucciarelli 《Pure and Applied Geophysics》1995,145(2):297-312
A multi-parametric study of empirical relationships between macroseismic data and magnitude is presented for the Italian region by the analysis of a new extended data set concerning 146 earthquakes. The available magnitude determinations include all of the most intense earthquakes which occurred in Italy in the last century and have been obtained by an accurate revision of original instrumental data. Intensity data have been revised and upgraded on the basis of the most recent studies: only local intensities directly documented have been used. Macroseismic determinations ofM
s
,m
B
andM
wa
magnitudes have been performed. The empirical relationships between maximum felt intensity (I
max
) and magnitude have been determined by the use of a distribution-free approach and a linear regression analysis. This last parameterization allows for the explanation of more than 60% of the variation in magnitude. In order to improve these results, the linear dependence between magnitude,I
max
and average distances (in logarithm) corresponding to fixed attenuation values has been explored. The comparison between instrumental magnitudes and corresponding macroseismic estimates obtained from empirical relationships shows that the respective uncertainties are comparable. 相似文献
209.
Christian Weiler 《Surveys in Geophysics》1995,16(5-6):671-679
For the purposes of a thesis at the Institute of avalanche and torrent control at the university of agriculture in Vienna a comparison of two avalanche-models, a hydraulic one from Voellmy/Salm/Gubler and a statistical one from Laatsch/Zenke/Dankerl with exemplary exactly known avalanches of Tyrol and Switzerland was started in 1993. The result of this work was that both models failed by the calculation of avalanches with high recurrence intervals (over 300 years). For the calculation of avalanches with recurrence intervals under 300 years the results of both models are regular. The conclusion is that a combination of two models i.e. a hydraulic one improved by statistical calculations will be the best. 相似文献
210.
Wind-tunnel experiments were carried out to measure the shear stressduring snow saltation. Shear stress acting on the snow surface, measured directly with a newly developed drag meter system, revealedthat the shear stress increased with the development ofsaltation. This result supports Owen's hypothesis that the saltationlayer acts as an increased roughness to the flow above the saltationlayer, leading to an increase in surface shear stress. To investigate the contribution of the grain borne shear stressg and the fluid shear stress f to the increment of the total shear stress total, g was calculated from the loss of horizontal momentum of saltating snowparticles. Since g is the largest contribution to theincrement of total, the collision of thesaltating particles is dominant for the shear stressmodification. The results qualitatively support the numericalsimulation reported by McEwan and Willetts. 相似文献