全文获取类型
收费全文 | 223篇 |
免费 | 2篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 20篇 |
大气科学 | 8篇 |
地球物理 | 46篇 |
地质学 | 69篇 |
海洋学 | 20篇 |
天文学 | 57篇 |
综合类 | 1篇 |
自然地理 | 8篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 20篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 2篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有229条查询结果,搜索用时 15 毫秒
61.
Climate change vulnerability depends on who you are, where you are and what you do. The indigenous communities who primarily depend on natural resources for subsistence livelihoods are among the first and most affected by climate change. Climate models have predicted pronounced warming in high altitude regions of the Himalayas. The transhumant communities of the Himalayas follow traditional lifestyles based on seasonal livestock rearing and subsistence agriculture. There is however, no information on how vulnerable transhumant communities are to climate change, and how vulnerability of transhumant herders differs across the mountainous areas of Nepal. Based on semi-structured interviews with transhumant herders and using the IPCC climate change vulnerability framework, this study assessed and compared the vulnerability of transhumant communities from three districts representing Eastern, Central and Western mountainous region of Nepal. The results showed that the livelihood vulnerability and the climate change vulnerability differ across sites; both of them having lowest index values in the Central region. The vulnerability dimensions viz. exposure, sensitivity and adaptive capacity are largely influenced by diversity in livelihood strategies, income sources and crops, and access to food, water and health facilities. The findings will inform the design of policies and programmes to reduce vulnerability and enhance adaptive capacity of indigenous communities in general and the transhumant communities of the Himalayas in particular. 相似文献
62.
Organotins, especially tributyltins (TBT) are highly toxic to many marine organisms. These compounds are introduced in marine waters by ship trafficking, ship scrapping activities, as antifouling compounds and sewage disposal. Marine fishes, crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from Mumbai, Goa and Karwar on the west coast of India. At these locations average organotin concentration found in fishes, clams, shrimps, squids and crabs was 108, 852, 179, 70 and 89 ng Sn g−1 dw, respectively. In all the samples butyltins dominated over phenyltins. The levels of organotins suggest that all the organisms were contaminated with organotins and their consumption may pose health problems to humans. 相似文献
63.
This paper studies the motion and orbital stability of the infinitesimal mass in the vicinity of the equilateral (triangular) Lagrangian points of the elliptic restricted three body problem, considering photo gravitational effects of both the primaries. The stability of the triangular points is studied under the effects of radiating primaries around the binary system (Achird, Luyten, αCen AB, Kruger-60, Xi-Bootis); using simulation technique by drawing different curves of zero velocity. 相似文献
64.
A general formalism for the investigation of the late time dynamics of the universe for any analytic f(R) gravity model, along with a cold dark matter, has been discussed in the present work. The formalism is then elucidated with two examples. The values of the parameters of the models are chosen in such a way that they are consistent with the basic observational requirement. 相似文献
65.
This paper studies the motion of an infinitesimal mass around triangular equilibrium points in the elliptic restricted three body problem assuming bigger primary as a source of radiation and the smaller one a triaxial rigid body. A practical application of this case could be the study of motion of a satellite under the effect of Sun and Earth. We have exploited the method of averaging used by Grebnikov (Nauka, Moscow, revised 1986) throughout the analysis of stability of the system. The critical mass ratio depends on the radiation pressure, oblateness, eccentricity and semi major axis of the elliptic orbits and the range of stability decreases as the radiation parameter increases. 相似文献
66.
In this paper, it is shown completely analytically that a spintessence model in the dust dominated universe can very well serve the purpose of providing an early deceleration and a present day acceleration. 相似文献
67.
The Nizamsagar is one of the most heavily silted Indian reservoirs, with a 60 per cent reduction in its storage capacity in just 40 years. At the present rate of siltation, the entire original storage capacity will have silted up in 70 years. The problem of siltation has a multitude of economic and environmental implications. The environmental management issues involved in the siltation of the Nizamsagar are identified and analysed in detail in this paper. Regular monitoring of siltation and the taking of timely corrective action would have reduced the extent of damage by siltation. 相似文献
68.
Ajeet Kumar Vishwakarma Rajendra Prasad Dileep Kumar Gupta Pradeep Kumar Varun Narayan Mishra 《Journal of the Indian Society of Remote Sensing》2018,46(6):973-980
The present study describes the ground based bistatic scatterometer measurements of ladyfinger crop at its various growth stages in the specular direction with the azimuthal angle (\( \phi = 0 \)) for the angular incidence angle ranging from 20° to 60° at the interval of 10° at HH and VV polarization. An outdoor ladyfinger crop bed of an area 4 × 4 m2 was specially prepared for the ground based bistatic scatterometer measurements. The crop growth variables like vegetation water content, leaf area index, fresh biomass, and plant height were also measured at the time of each bistatic scatterometer measurement. The specular bistatic scattering coefficients were found to be decreasing with the crop growth variables up to the maturity stage and then after it increased slightly. The linear regression analysis was carried out between specular bistatic scattering coefficient and crop growth variables at all the incidence angles for HH and VV polarization to select the optimum angle of incidence and polarization for the estimation of crop growth variables. The potential of subtractive clustering based adaptive neuro-fuzzy inference system was applied for the estimation of crop growth variables. The estimated values for different crop growth variables were found almost close to the observed values. 相似文献
69.
Narayan Kayet Khanindra Pathak Abhisek Chakrabarty Satiprasad Sahoo 《Environmental Earth Sciences》2018,77(8):308
The prime contribution of this assignment was to examine the hyperspectral remote sensing, based on iron ore minerals identification using spectral angle mapper (SAM) technique. Correlation analyses between field iron contents and environmental variables (soil, water, and vegetation) have been performed. Spectral feature fitting (SFF) and multi-range spectral feature fitting (MRSFF) methods were used for accuracy assessment in extracting iron ore minerals from Hyperion EO-1 data. Spectral inspections as a reference were used in SAM technique for image classification for iron ore minerals: Hematite (24.26%), Goethite (32.98%) and Desert (42.76). Iron ore minerals classification is justified by the United States Geological Survey (USGS) spectral library and field sample points. The regression analysis of USGS and Hyperion reflectance spectra has shown the moderate positive correlation. The regression analyses between iron ore contents and environmental parameters (soil, water, and vegetation) have shown the moderate negative correlation. The examination was significantly effectual in extracting iron ore minerals: Hematite (SFF RMSE?≤?0.51 MRSFF RMSE?≤?0.48), Goethite (SFF RMSE?≤?0.047 MRSFF RMSE?≤?0.438) and Desert (SFF RMSE?≤?0.63 and MRSFF RMSE?≤?0.50); and the MRSFF RMSE histograms indicate the above result likened to a conventional SFF RMSE. MRSFF RMS error result is best because multiple absorption features typically characterize spectral signatures. This analysis demonstrates the potential applicability of the methodology for iron minerals identification framework and iron minerals impact on environmental parameters. 相似文献
70.
Narayan Bose 《Geological Journal》2016,51(5):841-841