全文获取类型
收费全文 | 292篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 33篇 |
大气科学 | 14篇 |
地球物理 | 55篇 |
地质学 | 118篇 |
海洋学 | 9篇 |
天文学 | 58篇 |
综合类 | 7篇 |
自然地理 | 15篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 14篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 18篇 |
2012年 | 13篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有309条查询结果,搜索用时 15 毫秒
1.
R. Mohan K. Verma L. P. Mergulhao D. K. Sinha S. Shanvas M. V. S. Guptha 《Geo-Marine Letters》2006,26(5):265-273
Sediment trap samples collected from the Western Arabian Sea yielded a rich assemblage of intact and non-living (opaque white) pteropod tests from a water depth of 919 m during January to September 1993. Nine species of pteropods were recorded, all (except one) displaying distinct seasonality in abundance, suggesting their response to changing hydrographical conditions influenced by the summer/winter monsoon cycle. Pteropod fluxes increased during the April–May peak of the intermonsoon, and reached maximum levels in the late phase of the southwest summer monsoon, probably due to the shallowing of the mixed layer depth. This shallowing, coupled with enhanced nutrient availability, provides ideal conditions for pteropod growth, also reflected in corresponding fluctuations in the flux of the foraminifer Globigerina bulloides. Pteropod/planktic foraminifer ratios displayed marked seasonal variations, the values increasing during the warmer months of April and May when planktic foraminiferal fluxes declined. The variation in fluxes of calcium carbonate, organic carbon and biogenic opal show positive correlations with fluxes of pteropods and planktic foraminifers. Calcium carbonate was the main contributor to the total particulate flux, especially during the SW monsoon. In the study area, pteropod flux variations are similar to the other flux patterns, indicating that they, too could be used as a potential tool for palaeoclimatic reconstruction of the recent past. 相似文献
2.
K. N. Prudhvi Raju Sarvajeet Kumar Kshitij Mohan Manish Kumar Pandey 《Journal of the Indian Society of Remote Sensing》2008,36(3):283-288
With growing urban expanses, one of the pre-requisites for effective governance is Urban Information Systems (UIS) with content
down to individual properties (and individuals). The basic input i.e., a map, in UIS should show individual property boundaries
showing the plan outline of all structures existing within, at a scale of 1:1000 and larger with sub-metre to centimeters
planimetric and geometric accuracy. With very high resolution remote sensing data of the order of 1m available in hand, it
is possible to prepare maps with high resolution spatial content. The present exercise demonstrates a method of preparing
a geometrically and planimetrically accurate urban cadastral map on very large scale for a small area of about 5 sq km. IKONOS
merged data with 1m resolution is used for the purpose. Mapping was done in conjunction with on-site measurements and sketches.
Guides are used to maintain shape symmetry and accuracy of buildings and other features. Working out cost of mapping per unit
area is another objective in the present exercise. For want of fully or semi-automatic methods of information extraction from
very high resolution remote sensing data, it is imperative that mapping should be carried out in conjunction with some on-site
measurements wherever necessary. 相似文献
3.
Theoretical Ca X electron temperature sensitive emission line ratios, derived using electron excitation rates interpolated from accurateR-matrix calculations, are presented forR
1 =I(419.74 )/I(574.02 ,),R
2 =I(411.65 )/I(574.02 ),R
3 =I(419.74 )/I(557.75 ), andR
4 =I(411.65 )/I(557.75 ). A comparison of these with observational data for three solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on boardSkylab, reveals good agreement between theory and observation forR
1 andR
3 in one event, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, in the other flares the observed values ofR
1 –R
4 are much larger than the theoretical high-temperature limits, which is probably due to blending of the 419.74 line with Civ 419.71 , and 411.65 with possibly Ciii 411.70 . 相似文献
4.
Vijay Mohan 《Astrophysics and Space Science》1981,76(1):83-85
A period analysis of Ceti has been carried out and it has been found that the period of Ceti is increasing at a rate of 0.86 s per century. It is concluded that in its post-Main-Sequence evolution Ceti is in the early shell hydrogen-burning phase. 相似文献
5.
6.
The concept of the equivalent free surface has been extended to determine the seismic horizontal pullout capacity of shallow
vertical strip plate anchors buried in sand. The analysis has been done rigorously by using the method of stress characteristics.
The results have been expressed in the form of non-dimensional charts. The pullout resistance has been found to reduce quite
extensively with increase in the magnitude of horizontal earthquake acceleration. The results were compared with the previously
published data, and it was seen that the computed pullout resistance with the proposed method was found to be lowest.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
A GIS based hydrogeomorphic approach for identification of site-specific artificial-recharge techniques in the Deccan Volcanic Province 总被引:5,自引:0,他引:5
The Deccan Volcanic Province (DVP) of India, as a whole, faces a severe shortage of water despite receiving a high annual
rainfall, this is primarily due to excess runoff and lack of water conservation practices. In this study, an attempt is made
to identify zones favourable for the application and adaptation of site-specific artificial-recharge techniques for augmentation
of groundwater through a Geographical Information System (GIS) based hydrogeomorphic approach in the Bhatsa and Kalu river
basins of Thane district, in western DVP. The criteria adopted for the GIS analysis were based on the hydrogeomorphological
characteristics of both basins extracted from the IRS-1C LISS-III data supported by information on drainage pattern, DEM derived
slope, lineament density, drainage density, and groundwater condition. The integrated study helps design a suitable groundwater
management plan for a basaltic terrain. 相似文献
8.
Geological and geochemical study has been carried out to investigate arsenic contamination in groundwater in Nawalparasi, the western Terai district of Nepal. The work carried out includes analyses of core sediments, provenance study by rare earth elements analyses, 14C dating, and water analyses. Results showed that distribution of the major and trace elements are not homogeneous in different grain size sediments. Geochemical characteristics and sediment assemblages of the arsenic contaminated (Nawalparasi) and uncontaminated (Bhairahawa) area have been compared. Geochemical compositions of sediments from both the areas are similar; however, water chemistry and sedimentary facies vary significantly. Extraction test of sediment samples showed significant leaching of arsenic and iron. Chemical reduction and contribution from organic matter could be a plausible explanation for the arsenic release in groundwater from the Terai sediments. 相似文献
9.
10.
J. N. Hindayar P. Dasarwar S. P. Srivastava N. Thrideep Kumar Murali Mohan S. K. Som 《Journal of the Geological Society of India》2016,88(2):197-205
Understanding the causes of slope development with movement initiation of land sliding requires knowledge on dynamicity, displacement, strain concentration and factor of safety. The 13th mile landslide on Gangtok-Nathula road of the Sikkim Himalaya has seriously affected the Indo-China trade route. To quantify the spatial movement pattern, strain analysis and identification of zones of safety were attempted which indicates that differential movement activity of the landslide zone is co-relatable with differential strain pattern with an overall imprint of the Himalaya collision tectonics. 相似文献