全文获取类型
收费全文 | 128篇 |
免费 | 4篇 |
专业分类
测绘学 | 10篇 |
大气科学 | 9篇 |
地球物理 | 19篇 |
地质学 | 43篇 |
海洋学 | 5篇 |
天文学 | 38篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有132条查询结果,搜索用时 15 毫秒
91.
Estimating the uncertainty of land-cover extrapolations while constructing a raster map from tabular data 总被引:2,自引:0,他引:2
Robert Gilmore?Pontius Jr.Email author Aditya?Agrawal Diana?Huffaker 《Journal of Geographical Systems》2003,5(3):253-273
This paper presents novel techniques to estimate the uncertainty in extrapolations of spatially-explicit land-change simulation models. We illustrate the concept by mapping a historic landscape based on: 1) tabular data concerning the quantity in each land cover category at a distant point in time at the stratum level, 2) empirical maps from more recent points in time at the grid cell level, and 3) a simulation model that extrapolates land-cover change at the grid cell level. This paper focuses on the method to show uncertainty explicitly in the map of the simulated landscape at the distant point in time. The method requires that validation of the land-cover change model be quantified at the grid-cell level by Kappa for location (Klocation). The validation statistic is used to estimate the certainty in the extrapolation to a point in time where an empirical map does not exist. As an example, we reconstruct the 1951 landscape of the Ipswich River Watershed in Massachusetts, USA. The technique creates a map of 1951 simulated forest with an overall estimated accuracy of 0.91, with an estimated users accuracy ranging from 0.95 to 0.84. We anticipate that this method will become popular, because tabular information concerning land cover at coarse stratum-level scales is abundant, while digital maps of the specific location of land cover are needed at a finer spatial resolution. The method is a key to link non-spatial models with spatially-explicit models. 相似文献
92.
We present five new discriminant function diagrams based on an extensive database representative of basic and ultrabasic rocks
from four tectonic settings of island arc, continental rift, ocean-island, and mid-ocean ridge. These diagrams were obtained
after loge-transformation of concentration ratios of major-elements — a technique recommended for a correct statistical treatment of
compositional data. Higher % success rates (overall values from ∼ 83 to 97%) were obtained for proposing these new diagrams
as compared to those (∼82 to 94%) obtained from the discriminant analysis of the raw major-element concentration data (i.e.,
without the loge-transformation and without taking ratios of the compositional data, but using exactly the same database to provide an unbiased
comparison), suggesting that such a data transformation constitutes a statistically correct and recommended technique. The
new diagrams also resulted in less mis-classification of basic and ultrabasic rocks from known tectonic settings than the
diagrams obtained from the raw data. The use of these highly successful new discriminant function diagrams is illustrated
using Miocene to Recent basic and ultrabasic rocks from three areas of Mexico with complex or controversial tectonic settings
(Mexican Volcanic Belt, Los Tuxtlas volcanic field, and Eastern Alkaline Province), as well as older rocks from three areas
(Deccan, Malani, and Bastar) of India. Additionally, the major-element data from two ‘known’ continental arc settings are
used to show that they are similar to those from the island arc setting. Continental rift setting is inferred for all Mexican
cases and for one cratonic area of India (Malani) and an IAB setting for the Bastar craton. The Deccan flood basalt province
of India is used to warn against an indiscriminate use of those discrimination diagrams that do not explicitly include the
likely setting of the area under evaluation. An Excel template is also provided for an easy application of these new diagrams
for discriminating the four settings considered in this work. 相似文献
93.
The Himalayan mountain system has many depressions of regional dimensions, which are found oriented mostly E–W to NE–SW, mainly to the north of the main boundary fault (MBF). The Karewa Basin in the Kashmir Himalaya has sediments belonging to late Neogene to Quaternary formations, which represent an almost 1,300-m-thick succession of sand, mud and gravels exposed in the river valleys and the plateau margins of the entire Kashmir Valley. Sandbox analogue experiments show a great variety of wedge shapes showing significant changes in the taper angles due to the change in basal friction. Between two pop-ups or depressions (pop-down) of significant dimensions develop along the strike of the growing wedge. In order to maintain the critical angle, these depressions initially receive material from the hinterland, and later on, from the foreland end of the wedge. The depressions have developed due to the change in the surface slope of the wedge, and receive the eroded material only from the adjacent upheaved portions of the wedge. On continuation of the experiments (in cases where the wedge is highly unstable), these depressions are coupled with the wedge along with their sand-fills. The depositional history of the Karewa sediments indicates a sequential evolutionary pattern of the basin and thus represents a natural analogue of the sandbox experiments. 相似文献
94.
Nadeem Ahmed Anjum Mahtab Ritesh Agrawal P. Jayaprasad S. K. Pathan Ajai D. K. Singh A. K. Singh 《Journal of the Indian Society of Remote Sensing》2007,35(2):121-127
CARTOSAT-1 satellite, launched in May, 2005 is a dedicated along track stereo mission providing high quality data for topographic
and cartographic applications. The present paper describes the evaluation of the Cartosat-1 stereo data, mainly through the
generation and validation of DEM for moderately undulating and hilly areas. Photogrammetric techniques have been used for
generation of DEM and Orthoimage for two cases i.e. 1) using RPCs (Rational Polynomial Coefficients) and 2) using RPCs along
with ground control points. Root Mean Square Error (RMSE) in elevation values for the moderately undulating (Dehradun) and
hilly area (Shimla), are found to be 4.38 and 3.69m respectively. 相似文献
95.
Soft X-ray emission from the X-ray source Per X-1 was observed in the 0.4–2 keV energy interval from a rocket borne X-ray detector. Spectral analysis of the data indicates that in the 0.4–2 keV band the X-ray emission from Per X-1 can be fitted either with a power law of slope-(4.8±1.2) or a thermal bremsstrahlung spectrum with akT value of (0.26 ?0.08 +0.12 ) keV. Such a steep spectrum is inconsistent with the spectrum measured above 2 keV. The measured flux in 0.4–2 keV band corresponds to X-ray luminosity of 3×1045 ergs s?1 for Per X-1. 相似文献
96.
An analytical study is performed to examine the heat transfer characteristics on the flow of a viscous, incompressible rarefied gas in a parallel plate channel under the action of transverse magnetic field when (i) suction velocity normal to the plate is constant, (ii) the second plate oscillates in time about a constant non-zero mean, (iii) fluid is subjected to a constant heat source of absorption type. Apprximate solutions for velocity, temperature, phase, and amplitude of skin-friction and rate of heat transfer are evaluated. Mean temperature profiles, phase and amplitude of rate of heat transfer at both plates are discussed graphically followed by a quantitative discussion. Mean rate of heat transfer is tabulated in Table I. 相似文献
97.
A diffusion mechanism is proposed which takes into account phenomena observed in ion-implanted solids, in particular the precipitation of rare gas in the form of bubbles and their migration. The composition of rare gases in the bubbles is inferred from the calculated distribution of solar wind rare gas ions as a function of depth in the grains. These calculations are made for the location and average composition of Apollo 11 samples. It is shown by analogy with experimental observations in ion-implanted solids that the bubbles would migrate towards the surface and that the diffusion constant for this migration would be strongly depth dependent. Relative abundances of rare gas nuclides remaining behind due to the resultant degassing are estimated for one Apollo 11 soil sample and are compared with observed relative abundances for this sample. A qualitative explanation of some of the experimental observations of Ducati et al. on individual lunar grains is also offered. 相似文献
98.
The Tavidar volcanics belong to a trachybasalt-trachyandesite-rhyolite association. Distribution and behavior of major and trace elements and field relationships indicate that intermediate and acidic volcanics of the area are cogenetic, whereas the basaltic phase is younger. Cogeneticity also is confirmed by the mixing line calculation. In the present case, instead of two pole mixing, three pole mixing between end members andesite, quartztrachyte, and rhyolite has been considered. Results show that a perfect linearity in data exists between andesites and quartztrachyte and between quartztrachyte and rhyolites. 相似文献
99.
100.
R L Ahuja M L Manchanda B S Sangwan V P Goyal R P Agrawal 《Journal of the Indian Society of Remote Sensing》1992,20(2-3):105-120
Visual interpretation of IRS-1A LISS-II (October 1988 & Feb. 1989) FCC (spectral bands 2, 3 & 4) at 1:50,000 scale was carried out for soil resource mapping of Bhiwani district (Haryana State) covering on area of 5099 sq. kim. Based on image characteristics, element analysis (landform, vegetation & erosion) and field traverses, physiography-soil relationship was established. Major physiographic units identified in the area are: Aeolian plain, Fluvio-acolian plain, Transitional plain, Alluvial plain, Hills and Pediments. Area was divided into 34 subunits. Final physiography-soil map on 1:50,000 scale was prepared. Taxonomically, the soils of each unit were classified and are found as: In aeolian plain—Typic Torripsamments/coarse loamy, Typic Camborthios; Fluvio-aeolian plain-Aridic Ustipsamments/coarse loamy/fine loamy Typic/Udic Ustochrepts; Alluvial plain—Typic Ustipsamments/coarse loamy/fine loamy Typic/Udic Ustochrepts; Hills and Pediments—fregmental Lithic Torriorthents/Typic Torripsamments. Interpretation for each subunit was made regarding land suitability for various land utilisation types. It was found that hills and pediments, dunal ridges, dunal complexes and serub-lands are best suitable for forestry and horiculture plantations. Dunal plains and inter-dunal depressions are best suitable for gram/bajra/oilseeds/guar, very gently sloping dunal plain and low lying plain are suitable for wheat/arhar/cotton/sunflower. 相似文献