全文获取类型
收费全文 | 391篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 31篇 |
大气科学 | 15篇 |
地球物理 | 57篇 |
地质学 | 134篇 |
海洋学 | 15篇 |
天文学 | 128篇 |
综合类 | 9篇 |
自然地理 | 9篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 24篇 |
2017年 | 26篇 |
2016年 | 17篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 35篇 |
2012年 | 12篇 |
2011年 | 21篇 |
2010年 | 20篇 |
2009年 | 27篇 |
2008年 | 19篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 1篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有398条查询结果,搜索用时 15 毫秒
21.
B. M. Singh M. L. Manchanda H. S. Iyer L. M. Pande Jitendra Prasad B. R. M. Rao 《Journal of the Indian Society of Remote Sensing》1983,11(3):1-13
A critical appraisal of the need and use of remote sensing techniques for land use mapping with particular reference to Indian conditions have been made. Land use classification system based on physiography, utility, management and identification have been suggested using remote sensing techniques at different levels of mapping. 相似文献
22.
M. L. Manchanda H. S. Iyer B. M. Singh Jitendra Prasad 《Journal of the Indian Society of Remote Sensing》1983,11(3):67-74
The use of Landsat imagery at 1:1 M and 1:250,000 and aerial photos on 1:65,000 and 1:20,000 scale have been used to study landuse. It has been possible to achieve identification using Landsat imagery up to utility level ( level 1 and II ) and with the aerial photographs further subdivisions of utility into management and identification (level III and IV) . 相似文献
23.
Arecibo (18.4 N, 66.7 W) incoherent scatter (IS) observations of electron density N(h) are compared with the International Reference Ionosphere (IRI-95) during midday (10/14 h), for summer, winter and equinox, at solar maximum (1981). The N(h) profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option) and the Gulyaeva-B0 thickness (new option). The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option), are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0. 相似文献
24.
We have examined the global relation betwen the mean monthly surface level humidity and the precipitable water (Q-W relation) developed by Liu (1986) for its applicability to instantaneous data sets as proposed by Hsu and Blanchard (1989) over the Indian oceanic region. Our analysis using regional instantaneous values of W from Monex-79 in-situ data sets gave an rms error of 5.66gm/kg. This is considerably larger than the rms error of 0.4 gm/kg as obtained by Liu using the global mean monthly relation, thus failing to support Hsu and Blanchard's conjecture. However, a fifth-order polynomial in W derived by us based on instantaneous data indicates an rms error of 0.92 gm/kg. 相似文献
25.
Interactive visualization has been an integral part of landscape simulation to facilitate understanding of environmental processes.
In most cases, however, interaction with the data is limited to viewing only. Thus to support more 3D interaction, in this
study an attempt has been made to apply multi-view approach of the model for orientation, navigation and selection as visual
metaphors on the landscape. This paper further describes how JAVA 3D/VRML can be used to model a landscape for better user
interaction and exploration. Data used for generation of landscape model is SRTM-3 pertaining to a part of Alwar district
in Rajasthan. This study emphasizes the importance of user interaction with 3D landscape for visualizing future design implications,
landuse change and visual exploration. 相似文献
26.
27.
Development of irrigation potential for increasing agricultural production is the main aim of Command Area Development. This involves interaction amongst various factors; the soil, the crop, the climate, the topograpny and others. Water management in Command Area requires careful planning, based upon adequate data regarding soils, land use and topography. It is essential to make the best possible use of the available water without creating waterlogging, salinity and alkalinity problems in the command area. The use of aerial photographs is a well recognized expedient, convenient and economical method of data collection, which appreciably suits the requirement of the survey of Command Areas. As large areas have to be surveyed for data collection, the best way to accomplish this is by taking up survey of command area in different levels: reconnaissance, semi-detailed and detailed. The reconnaissance and semi-detailed survey would enable us to identify problem areas. Detailed survey are needed in these areas for taking up reclamation measures. A case study of soil survey carried out in the Sharda Sahayak Command Area of a part of Hardoi District is given as an example to illustrate the use of aerial photographs for planning of water management practices. 相似文献
28.
29.
The various forms of energy and energy conversions have been computed over a part of the Indian region during an active monsoon period, using the quasigeostrophic baroclinic model. The energetics of the monsoon depression have been discussed on the basis of these results. 相似文献
30.
Protein digestibility was determined via two feeding trials in glass aquaria by the indicator (Chromium oxide) method using a mixture of shrimp powder with oil cake and wheat bran respectively (1: 1 W/W) as food. Analyses of feed were made to calculate the crude protein, carbohydrate, lipid and ash contents. Feces were analysed to determine their total nitrogen and chromium oxide. Protein digestibility was studied in relation to salinity of the medium size and weight of the fish body. The apparent digestibility of crude protein of a corresponding die has shown that 1st: Younger fish do possess a lower capability of protein digestion than fish having a medium weight and medium size; 2nd: Older fish with a high weight and large size exhibit no improvement in efficiency to digest the food protein, though their weight and size are significantly greater than those of middle weight and medium size fish; 3rd: The replacement of oil cake by wheat bran decreases the protein digestibility of shrimp powder mixture with them; 4th: A salinity (NaCl) of the aquatic medium at or above 3 g/l depletes the protein digestibility when fish of the same size were experimented with; but a salinity up to 2 g/l does not result in a significant decrease in the protein digestion rate. 相似文献