全文获取类型
收费全文 | 335篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 40篇 |
大气科学 | 29篇 |
地球物理 | 44篇 |
地质学 | 102篇 |
海洋学 | 6篇 |
天文学 | 105篇 |
综合类 | 12篇 |
自然地理 | 4篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 23篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 20篇 |
2012年 | 11篇 |
2011年 | 17篇 |
2010年 | 16篇 |
2009年 | 15篇 |
2008年 | 8篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
排序方式: 共有342条查询结果,搜索用时 31 毫秒
91.
92.
M. V. Popov A. S. Andrianov N. Bartel C. Gwinn B. C. Joshi D. Jauncey N. S. Kardashev A. G. Rudnitskii T. V. Smirnova V. A. Soglasnov E. N. Fadeev V. I. Shishov 《Astronomy Reports》2016,60(9):792-806
The RadioAstron ground–space interferometer has been used to measure the angular sizes of the scattering disks of the three distant pulsars B1641–45, B1749–28, and B1933+16. The observations were carried out with the participation of the Westerbork Synthesis Radio Telescope; two 32-m telescopes at Torun, Poland and Svetloe, Russia (the latter being one antenna of the KVAZAR network); the Saint Croix VLBA antenna; the Arecibo radio telescope; the Parkes, Narrabri (ATCA), Mopra, Hobart, and Ceduna Australian radio telescopes; and the Hartebeesthoek radio telescope in South Africa. The full widths at half maximum of the scattering disks were 27 mas at 1668 MHz for B1641–45, 0.5 mas at 1668 MHz for B1749–28, and 12.3 at 316 MHz and 0.84 mas at 1668 MHz for B1933+16. The characteristic time scales for scatter-broadening of the pulses on inhomogeneities in the interstellar plasma τsc were also measured for these pulsars using various methods. Joint knowledge of the size of the scattering disk and the scatter-broadening time scale enables estimation of the distance to the effective scattering screen d. For B1641–45, d = 3.0 kpc for a distance to the pulsar D = 4.9 kpc, and for B1749–28, d = 0.95 kpc for D = 1.3 kpc. Observations of B1933+16 were carried out simultaneously at 316 and 1668 MHz. The positions of the screen derived using the measurements at the two frequencies agree: d 1 = 2.6 and d 2 = 2.7 kpc, for a distance to the pulsar of 3.7 kpc. Two screens were detected for this pulsar from an analysis of parabolic arcs in the secondary dynamic spectrum at 1668 MHz, at 1.3 and 3.1 kpc. The scattering screens for two of the pulsars are identified with real physical objects located along the lines of sight toward the pulsars: G339.1–04 (B1641–45) and G0.55–0.85 (B1749–28). 相似文献
93.
A. O. Varghese V. B. Sawarkar Y. L. P. Rao A. K. Joshi 《Journal of the Indian Society of Remote Sensing》2016,44(1):49-57
Ardeotis nigriceps, commonly known as Great Indian Bustard (GIB), is a Critically Endangered, Evolutionary Distinct and Globally Threatened (EDGE) and endemic species to the Indian subcontinent. GIB is under tremendous threat in its last strongholds and sliding inextricably towards extinction. The GIB sanctuary in Maharashtra (India) is one of the last refuges of the bird constituting an area of 8496 km2 spread over in seven talukas of Solapur and Ahemednagar districts. Major portion of the sanctuary (94.3 %) consists of privately owned lands under a variety of economic vocations and large number of villages and townships. In view of the legal restrictions relating to Protected Area under the Wildlife (Protection) Act of India 1972, the inhabitants of villages and townships faced a very difficult situation regarding use of their lands, development of properties and deriving benefits from planned local and regional development. This created conflict between local people and the forest department over the use of land, which necessitated the rationalization of the sanctuary. The objective of the present study was to map the suitable habitat of GIB in GIB Wildlife Sanctuary as an input for the realignment of the GIB Sanctuary by identifying areas that are important for the GIB. Main parameters considered for the habitat suitability assessments are, habit and habitat of GIB, slope, minimum patch size and disturbance sources. Based on the criteria derived for the ecological and biological requirements of GIB, binary deductive habitat suitability modeling has been done using remote sensing and GIS and prioritized the potential habitats of GIB. The net area of important suitable habitat of GIB in GIB sanctuary is 2304.99 km2 out of 8496.44 km2. The output of the present study has been used as an input by the committee (set by Honorable Supreme court of India) on rationalization of the GIB Sanctuary and the sanctuary has been rationalized with an area of 1222 km2. 相似文献
94.
Sitiraju Srinivasa Rao Dinesh Kumar Sahadevan Milind R. Wadodkar M/ S. S. Nagaraju Sudipta Chattaraj William Joseph Prasanth Rajankar Titu Sengupta M. V. Venugopalan Subrata N. Das Asok Kumar Joshi Jaswanth Raj Sharma Eadara Amminedu 《Journal of the Indian Society of Remote Sensing》2016,44(2):277-285
95.
Ten spectrograms of T Vul at a dispersion of 8.47 Å mm–1 have been used for an analysis of the parameters of stellar atmosphere during its pulsation cycle. A differential curve of growth method relative to the Sun has been used to evaluate atmospheric parameters. The range in exc is from 0.88 to 1.00. Mean abundances for twenty elements have been estimated relative to [N
Fe]. A deficiency by a factor of 2.4 has been found ins-process elements with respect to those formed by thee-process. 相似文献
96.
N. Jackson R. A. Battye I. W. A. Browne S. Joshi T. W. B. Muxlow P. N. Wilkinson 《Monthly notices of the Royal Astronomical Society》2007,376(1):371-377
We have used the very large JVAS/CLASS 8.4-GHz surveys of flat-spectrum radio sources to obtain a large, uniformly observed and calibrated, sample of radio source polarizations. These are useful for many investigations of the properties of radio sources and the interstellar medium. We discuss comparisons with polarization measurements from this survey and from other large-scale surveys of polarization in flat-spectrum sources. 相似文献
97.
98.
Tandon Ruchika Sharma Gupta Vikram Venkateshwarlu Bhimala Joshi Pradeep 《Natural Hazards》2022,113(2):1017-1042
Natural Hazards - In the present study, slope stability analysis was done using limit equilibrium method and finite element method of the Dungale landslide situated in the NW Himalaya along Tons... 相似文献
99.
Natural Hazards - Avalanche forecasting is carried out using physical as well as statistical models. All these models have certain limitations associated with their mathematical formulation that... 相似文献
100.
B. K. Joshi 《Water Resources》2006,33(1):87-96
The study aims to measure the hydrological behavior and nutrients dynamics of the springs located in different landscapes of Kosi basin, Indian central Himalaya. A total number of eight springs were considered for the present investigation, each landscape represented by one spring. The monitoring for hydrological measurement was conducted in January 1998 to December 1999, the interval between two successive measurements was 10 days, i.e., 240 hr (total 72 observations were made). Water quality measurement was done in three main seasons, i.e., winter (Jan.), summer (June) and monsoon (Aug.) of 1998 and 1999, and the average value for measured parameters were calculated. These samples were analyzed for pH, electrical conductivity, total dissolved solids, dissolve oxygen, Ca2?, Mg2?, Na?, Cl?, F?, NO 3 ? , and SO 4 2? . Hydrology of spring’s water showed that the reserve forest has a higher water retention capacity than the other landscapes, and the spring recharge capacity highly influenced by the settlements, open grazing, mismanaged agricultural and deforestation activities. The spring water chemistry shows that the springs located in forest and sparsely populated areas have lower EC, TDS, cationic and anionic concentration and are safe for drinking purposes, but those in irrigated land and densely populated areas feature higher EC, low dissolved oxygen concentration and higher NO 3 ? , which makes the water of these springs unsuitable for drinking. F concentration was higher in the springs located in the settlement area. In brief, the study indicates that the unmanaged drains, very poor and old pattern of sewage disposing system result in an increase in Na?, Cl?, F?, NO 3 ? , and SO 4 2? concentration as compared to the springs in agricultural and forested areas. All of the studied springs are badly managed which a is great threat for the longevity and quality of the water bodies, in particular, in Indian Central Himalayan region. This study suggests the ways of the constructional works, grazing. Forest resource extraction and agricultural activities in water bodies catchments area should also be controlled. 相似文献