全文获取类型
收费全文 | 144篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 13篇 |
地球物理 | 18篇 |
地质学 | 59篇 |
天文学 | 33篇 |
综合类 | 3篇 |
自然地理 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 12篇 |
2013年 | 21篇 |
2012年 | 6篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2000年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有149条查询结果,搜索用时 15 毫秒
91.
Assuming local thermodynamic equilibrium and the same relative abundances to prevail both in photosphere and faculae, the concentration-optical depth curves for molecules CH, NH, OH, C2, CN and CO have been obtained for the four combinations of two photospheric and two facular models and the relative excesses of these molecules in the photosphere over those in faculae have been calculated. The change of photospheric model significantly affects the relationship, for a given facular model, between and D
0, the dissociation energy of the molecule concerned. Besides, the average depth of formation in the facular models and photospheric models shows a relationship with D
0. 相似文献
92.
Vijay S. Tripathi 《Journal of Geochemical Exploration》1979,11(3):263-275
Soil samples collected in the vicinity of a small sulfide mineralization were analyzed for Cu, Zn, Cd, Pb, Ag, Mn, Ni, Co, Cr, and Mo. Factor analysis was used to study the interrelationships among these variables. Selective removal of some samples prior to factor analysis proved to be an important tool in exposing “hidden” relationships between samples, variables, and factors. It has been demonstrated that factor analysis is a suitable technique for data reduction in geochemical exploration since factor scores can be used, instead of raw variables, for interpretation of field observations and location of anomalies. 相似文献
93.
BISHWAKARMA Kiran WANG Guan-xing ZHANG Fan ADHIKARI Subash KARKI Kabita GHIMIRE Archana 《山地科学学报》2022,(2):388-402
The hydrochemical characterization and irrigation suitability assessment of the Ganges-Brahmaputra River System (GBRS) has immense importance for the livelihood... 相似文献
94.
Hydro-morphometrical analyses of sub-himalyan region in relation to small hydro-electric power 总被引:1,自引:0,他引:1
Kishan Singh Rawat A. K. Mishra Vinod Kumar Tripathi 《Arabian Journal of Geosciences》2013,6(8):2889-2899
The choice of site for small hydropower potentials in the inaccessible tracts of Himalayan region is a difficult task by the conventional methods. Present work suggests a site for developing a multipurpose small reservoir under GIS framework, in the Sub Himalayan region, India. Scarcity of geographical, climate and statistical data was the main problem for development of seasonal precipitation and runoff modeling for assessing water potentials and identification of possible small-scale hydropower sites. Small hydropower potential is mainly regulated by head and its durability available at site depending upon capacity of the watershed, underlying the reservoir, to produce the runoff. The study reveals that the Bari-Ka- Khad watershed (BKW) can be considered as a suitable site of interest for small-scale hydropower installation. It is having maximum drainage density (7.45 km/km2) and maximum available relief ratio (0.12), which demonstrates better capacity to produce runoff. According to drainage texture of BKW (Rt?=?2.35), it come under coarse texture and higher values of Rho coefficient (ρ?=?3.65), suggesting higher hydrologic storage during rainfall and attenuation of effects of erosion during elevated discharge. 相似文献
95.
Nachiketa Acharya Ankita Singh U. C. Mohanty Archana Nair Surajit Chattopadhyay 《Natural Hazards》2013,66(2):851-871
The drought during the months of June to September (JJAS) results in significant deficiency in the annual rainfall and affects the hydrological planning, disaster management, and the agriculture sector of India. Advance information on drought characteristics over the space may help in risk assessment over the country. This issue motivated the present study which deals with the prediction of drought during JJAS through standardized precipitation index (SPI) using nine general circulation models (GCM) product. Among these GCMs, three are the atmospheric and six are atmosphere–ocean coupled models. The performance of these GCM’s predicted SPI is examined against the observed SPI for the time period of 1982–2010. After a rigorous analysis, it can be concluded that the skill of prediction by GCM is not satisfactory, whereas the ability of the coupled models is better than the atmospheric models. An attempt has been made to improve the accuracy of predicted SPI using two different multi-model ensemble (MME) schemes, viz., arithmetic mean and weighted mean using singular value decomposition-based multiple linear regressions (SVD-MLR) of GCMs. It is found that among these MME techniques, SVD-MLR-based MME has more skill as compared to simple MME as well as individual GCMs. 相似文献
96.
Digital elevation model (DEM) data of Shuttle Radar Topography Mission (SRTM) are distributed at a horizontal resolution of 90 m (30 m only for US) for the world, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM data provide 30 m horizontal resolution, while CARTOSAT-1 (IRS-P5) gives 2.6 m horizontal resolution for global coverage. SRTM and ASTER data are available freely but 2.6 m CARTOSAT-1 data are costly. Hence, through this study, we found out a horizontal accuracy for selected ground control points (GCPs) from SRTM and ASTER with respect to CARTOSAT-1 DEM to implement this result (observed from horizontal accuracy) for those areas where the 2.6-m horizontal resolution data are not available. In addition to this, the present study helps in providing a benchmark against which the future DEM products (with horizontal resolution less than CARTOSAT-1) with respect to CARTOSAT-1 DEM can be evaluated. The original SRTM image contained voids that were represented digitally as ?140; such voids were initially filled using the measured values of elevation for obtaining accurate DEM. Horizontal accuracy analysis between SRTM- and ASTER-derived DEMs with respect to CARTOSAT-1 (IRS-P5) DEM allowed a qualitative assessment of the horizontal component of the error, and the appropriable statistical measures were used to estimate their horizontal accuracies. The horizontal accuracy for ASTER and SRTM DEM with respect to CARTOSAT-1 were evaluated using the root mean square error (RMSE) and relative root mean square error (R-RMSE). The results from this study revealed that the average RMSE of 20 selected GCPs was 2.17 for SRTM and 2.817 for ASTER, which are also validated using R-RMSE test which proves that SRTM data have good horizontal accuracy than ASTER with respect to CARTOSAT-1 because the average R-RMSE of 20 GCPs was 3.7 × 10?4 and 5.3 × 10?4 for SRTM and ASTER, respectively. 相似文献
97.
Mudslides and debris flows are now more common problems in tropical regions than landslides. This article addresses the issue of modelling mudslide-susceptible locations using an information value approach. Landsat 7 (ETM+) was employed to create a land-use map with limited field checks. Other parameters considered were lineament, road, soil, stream network and lithology. Topographic parameters such as slope and aspect play a dominant role in slope stability studies. Maps for slope and aspects were developed from a digital elevation model using statistical surface interpolation techniques. This article offers insight into the importance of the selection of suitable surface interpolation techniques. The three surface interpolation techniques evaluated in the study were: inverse distance weighted, Kriging and Spline. These were found to have varied accuracies of interpolation surfaces for all parameters, including elevation, slope and aspect. Surfaces offering the best accuracy were adopted for the information value approach for mudslide susceptibility zonation. 相似文献
98.
Shipra Shah Dharam Prakash Sharma Nazir A. Pala Priyanka Tripathi Munesh Kumar 《山地科学学报》2014,11(4):959-966
The present study was conducted in Solan Forest Division of Himachal Pradesh covering an area of about 57,158 ha. The aim was to estimate and assess the temporal change in carbon stock of the Chil Working Circle, in two forest ranges of the Division, Solan and Dharampur, over the period of 1956-2011. The inventory data of the working plans of Solan Forest Division from 1956-1957, 1984-1985 and 2002- 2003 were used in the present study while field data for biomass estimation was collected for the year 2011. The results showed a declining trend in carbon stock over 1956-1984 period, however, an increasing trend over 1984-2002 was observed, which showed a further increase for the period 2002-2011. These fluctuating trends in the forest carbon stock can be related to increasing anthropogenic pressure on forests and the subsequent introduction of a ban on green felling envisaging efficient forest management, both of which affect the forest carbon pool significantly. 相似文献
99.
A laboratory plasma experiment has been built to study the eruption of arched magnetic flux ropes (AMFRs) in the presence of a large magnetized plasma. This experiment simulates the eruption of solar AMFRs in two essential steps: i) it produces an AMFR (n=6.0×1012 cm?3, $T_{\rm e} = 14~\mathrm{eV}$ , B≈1 kilo-gauss, L=0.51 m) with a persistent appearance that lasts several Alfvén transit times using a lanthanum hexaboride (LaB6) plasma source, and ii) it generates controlled plasma flows from the footpoints of the AMFR using laser beams. An additional LaB6 plasma source generates a large magnetized plasma in the background. The laser-generated flows trigger the eruption by injecting dense plasma and magnetic flux into the AMFR. The experiment is highly reproducible and runs continuously with a 0.5 Hz repetition rate; hence, several thousand identical loop eruptions are routinely generated and their spatio-temporal evolution is recorded in three-dimensions using computer-controlled movable probes. Measurements demonstrate striking similarities between the erupting laboratory and solar arched magnetic flux ropes. 相似文献
100.
Predicted equivalent widths and profiles of facular CN lines are used here as a diagnostic tool for different model atmospheres. 相似文献