全文获取类型
收费全文 | 101篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 8篇 |
地球物理 | 7篇 |
地质学 | 20篇 |
海洋学 | 9篇 |
天文学 | 53篇 |
自然地理 | 4篇 |
出版年
2021年 | 2篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 15篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有104条查询结果,搜索用时 828 毫秒
71.
Natural Hazards - Using a high-resolution daily gridded rainfall data set for the period 1951–2015, new objective criteria were developed to determine rainstorms over the Indian region during... 相似文献
72.
Kinematical distances are estimated for six open star clusters. They agree fairly well with the photometric distances. The
kinematical distances cannot, at present, be estimated better than the photometric distances. When more accurate proper motion
measurements become available the kinematical distances will improve considerably and may then be used to calibrate the cosmic
distance scale. 相似文献
73.
74.
Mathematical Geosciences - 相似文献
75.
76.
Sankaran Adarsh Chavan Sagar Rohidas Ali Mumtaz Sindhu Archana Devarajan Dharan Drisya Sasi Khan Muhammad Ismail 《Natural Hazards》2021,106(3):1951-1979
Natural Hazards - This study investigated the multifractal characteristics of fine resolution (0.25ox0.25°) daily gridded rainfall fields of India over the period 1901–2013 to examine... 相似文献
77.
Gopal-Krishna Alok C. Gupta Ram Sagar Paul J. Wiita U. S. Chaubey C. S. Stalin 《Monthly notices of the Royal Astronomical Society》2000,314(4):815-825
We report results of the observations at the Vainu Bappu Observatory and the Uttar Pradesh State Observatory of eight radio-quiet quasi-stellar objects (RQQSOs) during 1996–99. This is a part of our ongoing programme to search for intranight optical variability in RQQSOs. Additional evidence for very rapid variability in three of the five optically bright and very luminous RQQSOs we had observed earlier, 1049−006, 1444+408 and 1630+377, was found. Of the three newly observed RQQSOs, the data for 0043+039 are too noisy to allow conclusions about variability to be drawn, but 0748+294 and 0824+098 show strong hints of microvariability. We also present a summary of the results from our entire programme to date, which includes observations of 16 radio-quiet QSOs and one radio-weak QSO, and compare the general properties of rapid variability in radio-quiet versus radio-loud AGN as determined from our work and that of several other groups. Observations of this kind are likely to play a key role in understanding the relative contributions of accretion discs and relativistic plasma jets to rapid optical fluctuations of AGN. 相似文献
78.
Bharat Prashad BHATT Sagar GODAR CHHETRI Thakur SILWAL Megharaj POUDEL 《资源与生态学报(英文版)》2021,12(5):620-627
Forests are major sources of energy, timber and non-timber forest products, medicinal and aromatic plants, hydrological functions, biodiversity conservation, and also fundamental sources of revenue collection to the nation. Studies indicate that forests could significantly enhance economic growth and create employment opportunities for local communities under intensive management. This paper aims to predict the contribution of the forest sector to the national economy. The economic facets of forestry considered in this paper are revenue generated from timber, non-timber forest products (NTFPs) and medicinal and aromatic plants (MAPs), and protected areas. The ARIMA model was used to forecast the economic contribution of the forestry sector. The study found that the total revenue generated from the selling of timber and fuelwood (USD 50.19 million) was higher than the total revenue collected from protected areas (USD 37.58 million) and NTFPs/MAPs (USD 6.9 million) in the past 15 years. The model projected that the mean revenue for the timber and fuelwood sale will USD 3.5 million for the next ten years. Similarly, the mean revenue will be generated about USD 0.5 million and USD 6.2 million from NTFPs/MAPs and protected areas, respectively, for the next ten years. The study limits to take account the in-kind use of forest products such as timber, fodder, fuelwood, etc., as used by community people within a forest users’ groups. Thus, practicing sustainable forest management, enabling policy documents, establishing forest-based industries, establishing forestry nurseries, conducting agroforestry practices, and tenure security could enhance the forestry sector's economic aspects. 相似文献
79.
Mathematical Geosciences - 相似文献
80.