全文获取类型
收费全文 | 32241篇 |
免费 | 517篇 |
国内免费 | 371篇 |
专业分类
测绘学 | 1232篇 |
大气科学 | 2470篇 |
地球物理 | 6278篇 |
地质学 | 11350篇 |
海洋学 | 2532篇 |
天文学 | 7702篇 |
综合类 | 144篇 |
自然地理 | 1421篇 |
出版年
2021年 | 279篇 |
2020年 | 278篇 |
2019年 | 324篇 |
2018年 | 823篇 |
2017年 | 785篇 |
2016年 | 1027篇 |
2015年 | 598篇 |
2014年 | 965篇 |
2013年 | 1697篇 |
2012年 | 1044篇 |
2011年 | 1284篇 |
2010年 | 1079篇 |
2009年 | 1399篇 |
2008年 | 1217篇 |
2007年 | 1170篇 |
2006年 | 1182篇 |
2005年 | 986篇 |
2004年 | 879篇 |
2003年 | 871篇 |
2002年 | 863篇 |
2001年 | 775篇 |
2000年 | 749篇 |
1999年 | 684篇 |
1998年 | 629篇 |
1997年 | 634篇 |
1996年 | 569篇 |
1995年 | 535篇 |
1994年 | 509篇 |
1993年 | 430篇 |
1992年 | 389篇 |
1991年 | 416篇 |
1990年 | 420篇 |
1989年 | 392篇 |
1988年 | 365篇 |
1987年 | 437篇 |
1986年 | 364篇 |
1985年 | 449篇 |
1984年 | 482篇 |
1983年 | 468篇 |
1982年 | 450篇 |
1981年 | 366篇 |
1980年 | 365篇 |
1979年 | 312篇 |
1978年 | 310篇 |
1977年 | 298篇 |
1976年 | 265篇 |
1975年 | 256篇 |
1974年 | 281篇 |
1973年 | 308篇 |
1972年 | 197篇 |
排序方式: 共有10000条查询结果,搜索用时 968 毫秒
301.
K. Vinod kumar R. C. Lakhera Tapas R. Martha R. S. Chatterjee A. Bhattacharya 《Environmental Geology》2008,55(4):789-799
Mass movements such as landslides in mountainous terrains are natural degradation processes and one of the most important
landscape-building factors. Varunawat Parbat overlooking Uttarkashi town witnessed a series of landslides on 23 September
2003 and the debris slides and rock falls continued for 2 weeks. This landslide complex was triggered due to the incessant
rainfall prior to the event, and its occurrence led to the blockage of the pilgrim route to Gangotri (source of the Ganges
river) and evacuation of thousands of people to safer places. Though there was no loss of lives due to timely evacuation,
heavy losses to the property were reported. High-resolution stereoscopic earth observation data were acquired after the incidence
to study the landslide in detail with emphasis on the cause of the landslide and mode of failure. Areas along the road and
below the Varunawat foothill region are mapped for landslide risk. It was found that the foothill region of the Varunawat
Parbat was highly disturbed by man-made activities and houses are dangerously located below steep slopes. The potential zones
for landslides along with the existing active and old landslides are mapped. These areas are critical and their treatment
with priority is required in order to minimise further landslide occurrences. 相似文献
302.
303.
G. R. Cooper G. Petrie A. D. N. Smith M. Sowton K. B. Atkinson 《The Photogrammetric Record》1969,6(33):239-258
The International Society for Photogrammetry held the Xlth International Congress at Lausanne during July 1968. The authors review the activities of five of the seven I.S.P. Commissions. 相似文献
304.
305.
306.
Ohne Zusammenfassung 相似文献
307.
M. A. Anastassiades L. N. Carapiperis N. K. Kariambas P. G. Paraskevopoulos 《Pure and Applied Geophysics》1962,52(1):143-152
Summary In this study the different forms of the electromagnetic field strength recordings at the Thera-Crete microwave line of link are examined, in comparison with the corresponding weather situations prevailing over that area. According to the amplitude of fluctuations, the different forms of recordings have been classified in three basic typesA, B, C and the annual frequency of the appearance of these types has been observed. Finally, the influence of weather situations on radio wave propagation was examined and it has been found that in most cases a close relationship exists between weather situations and the different fading forms of the electromagnetic field so that a prediction of the fading form be possible by means of the weather forecast.This study was sponsored by a research grant from NATO's Scientific Committee. 相似文献
308.
A. K. Mal M.Sc. 《Pure and Applied Geophysics》1962,52(1):59-68
Summary The effect of thickening of the crustal layer in mountainous region on the dispersion curve of Love waves has been studied. Perturbation method has been applied to obtain the modified frequency equation for Love waves through the surface of separation between a semi-infinite material and a layer the thickness of which abruptly increases throughout a certain length of the path. The effect is to decrease the phase velocity of the waves particularly in the low period range. It has been pointed out that by proper study, the amount of thickening may be obtained. 相似文献
309.
310.