全文获取类型
收费全文 | 342篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 25篇 |
大气科学 | 68篇 |
地球物理 | 57篇 |
地质学 | 120篇 |
海洋学 | 11篇 |
天文学 | 53篇 |
综合类 | 6篇 |
自然地理 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 31篇 |
2017年 | 25篇 |
2016年 | 29篇 |
2015年 | 25篇 |
2014年 | 29篇 |
2013年 | 29篇 |
2012年 | 34篇 |
2011年 | 21篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 13篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有358条查询结果,搜索用时 31 毫秒
81.
Haimanti Biswas Mitali Dey Dipnarayan Ganguly Tarun K. De Sandip Ghosh Tapan K. Jana 《Estuaries and Coasts》2010,33(2):384-394
Inter-annual variations of phytoplankton abundance and community organization were observed over a two-decade period along with the ancillary parameters at the land–ocean boundary associated with the Sundarban mangrove forest (21°32′ and 22°40′ N and 88°05′ and 89° E), along the NE Coast of the Bay of Bengal. The number of definable Bacillariophyceae species exceeded Dinophyceae taxa, and the total number of bloom-forming species declined from a maximum of ten in 2000 and a minimum of two in 2007. Blooms of the diatom Coscinodiscus radiatus were common in 2000 and 2007. Tide cycles and the onset of the monsoon season played important roles in diurnal and seasonal variability of phytoplankton. Phytoplankton biovolume showed seasonality, with the highest levels during post-monsoon periods and lowest levels during the monsoon period. Phytoplankton abundance was correlated to rainfall patterns, which may be altered by long-term changes in climate. 相似文献
82.
The spatiotemporal features of tropical cyclone strikes from 1949 to 2008 at 49 coastal cities of China are investigated in this study. The cities in Hainan, Guangdong, and Taiwan have high strike frequencies, with the severest and most frequent average strikes found in Taiwan. In Hainan, strike clusters appear in the mid-1950s, the early 1960s and 1970s, and the late 1980s, with relative inactive frequencies from the mid-1990s to 2008, and the clusters of strikes in Guangdong are found during the 1970s. In Taiwan, the most active strikes are found during the period 1956–1963. The return periods for all typhoons are either 1 or 2 years at the coastal cities of Taiwan in contrast to 2–5 and 4–8 years at the cities of Guangdong and Fujian, respectively. Super typhoons affect Taiwan with a frequency of once every 12–30 years on average. A tropical cyclone hazard index is also created to investigate the vulnerability at these cities. 相似文献
83.
Suchithra Sundaram R. Krishnan Ayantika Dey P. Swapna 《Meteorology and Atmospheric Physics》2010,107(1-2):17-31
The present study focuses on understanding the dynamics of intensification of the boreal summer monsoon cross-equatorial flow generally observed during positive-Indian Ocean Dipole (IOD) events, by taking 1994 as a case study. In particular, the influence of the anomalous divergent motions during 1994 (i.e., east–west circulation over equatorial Indian Ocean and the monsoon Hadley-type circulation) on the intensification of summer monsoon cross-equatorial flow is investigated. This problem is examined using diagnostic analyses and simulation experiments from a multi-level global atmospheric model forced with observed diabatic heating. The results suggest that the transfer of kinetic energy (KE) from the divergent motions to the rotational flows can be very effective during IOD periods like 1994; and provides a plausible explanation for the increase of KE of the monsoon cross-equatorial flow over Bay-of-Bengal and adjoining areas. The study also investigates the enhanced activity of westward propagating disturbances observed during 1994 over the monsoon region. 相似文献
84.
Len R. Garces Michael D. Pido Robert S. Pomeroy Sonny Koeshendrajana Budi Iskandar Prisantoso Nurul Ahmad Fatan Dedi Adhuri T. Raiful Syamsul Rizal Alexander Tewfik Madan Dey 《Ocean & Coastal Management》2010,53(2):69-79
This paper describes the application of the methodology called Rapid Appraisal of Fisheries Management System (RAFMS) to assess quickly the situation in tsunami-affected coastal fisheries in Aceh Province, Indonesia. As a diagnostic tool, the RAFMS is introduced in terms of its conceptual framework and procedures. The RAFMS was used to appraise the status of the fisheries sector in selected 15 villages. Information generated concerning level of fishing effort, marketing patterns and community perspectives on livelihood options are used as three illustrative examples. The paper also provides some insights in applying the RAFMS methodology in the context of disasters and in the broader context of tropical fisheries management. 相似文献
85.
The Koyna River basin in India drew the attention of geoscientists after an earthquake (magnitude 7) in 1967. Since then,
detailed geological, tectonic, and seismic investigations of this river basin have been carried out by several workers. However,
very little study has been done on its hydrogeological framework. The present work aims at filling this gap. Basalts, laterites,
alluvium, soils, and talus deposits form shallow unconfined aquifers, with transmissivity of 27–135 m2/d and a regional specific yield of 0.012. In shallow basaltic aquifers, the lower part of the highly weathered and highly
jointed horizon above, and the poorly weathered and highly jointed horizon below, form the most potential zone for groundwater
occurrence. Well yields in the deeper basaltic aquifers are directly related to the occurrence of lineaments, whereas at a
shallower level they are related to geomorphic features. Spring discharges are highly dependent on their source aquifers and
areas of recharge. They have a mean winter discharge of 46 m3/d and a summer discharge of 28 m3/d.
Chemically, groundwaters are dominated by alkaline earths (Ca2+, Mg2+) and weak acids (HCO3
–, CO3
–); they are calcium-bicarbonate type (53%) and calcium-magnesium-bicarbonate type (27%) at shallower levels; and calcium-magnesium-bicarbonate
type (29%), sodium-bicarbonate type (24%), calcium-bicarbonate type (19%), and calcium-magnesium-sodium-bicarbonate type (19%)
in deeper aquifers. The Koyna River basin is characterized by both scarcity and abundance of groundwater. In the water-scarce
areas in the dissected plateaus, artificial recharge of aquifers through construction of several recharge structures at suitable
locations is highly recommended. In the water-abundant areas in the central valley, on the other hand, expanded consumptive
use of water resources is encouraged.
Electronic Publication 相似文献
86.
Dilip G. Durbude B. K. Purandara Arun Sharma 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):47-58
An accurate assessment of run-off through aerial rainfall is a basic concept in most of the rainfall-runoff models, particularly conceptual models which emphasis a complete water balance. The run-off measurements by gauging can only be regarded as an index of rainfall and restrict our ability to successfully model the rainfall-runoff process. To overcome some of these problems, remote sensing satellite data are of immense use, particularly in mountainous and desert areas. Therefore in the present study, a typical watershed from a drought hit Banswara district of Rajasthan has been analysed using IRS-1B-LISS II satellite imagery for estimating the run-off potential under different geomorphic set-up. The run-off potential was estimated using SCS method based on the satellite data in conjunction with ground truth information collected during field visit. The results indicated that the soil and water conservation measures in the watershed would improve the existing water potential and storage capacity of the study area. Based on the study eight check dams and five lift irrigation schemes are proposed. 相似文献
87.
The effect of different concentrations, viz. 0.01, 0.001 and 0.0001 ppm of methyl mercuric chloride on survival, growth behaviour and chlorophyll content of Chlorella vulgaris has been studied under various environmental conditions. Methyl mercury at 0.01 ppm is 100% toxic to the test alga. At a sublethal (0.001 ppm) dose of CH3HgCl, Chlorophyll a was more inhibited than Chlorophyll b. Toxicity was found to be very much under the influence of pH as at acid pH growth is highly reduced by a sublethal concentration, whereas the same concentration does not have an inhibitory influence in the alkaline range of pH. Eutrophic waters seem to reduce the heavy metal toxicity in general. 相似文献
88.
Sukhendu Dey 《Pure and Applied Geophysics》1972,94(1):53-59
Summary In this paper, the frequency equation for phase velocity of torsional wave in a rod of circular cross section under initial tension has been obtained. The graphs are plotted to compare the velocity with that in the absence of initial tension. Some analytical informations have been obtained for instability of the body under initial compression. 相似文献
89.
Saurabh Baruah Goutam Kashyap Boruah Sangeeta Sharma Washim Akram Hoque Timangshu Chetia Chandan Dey 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2020,14(2):112-127
ABSTRACTThe concept of seismic vulnerability is a yard-stick of damage estimation from a probable earthquake considering physical cum social dimension and enables a basis for decision-makers to develop preparedness and mitigation strategies. We aim at vulnerability assessment of the typical urban system of capital city Shillong situated on hilly terrain. High-resolution satellite imagery of Shillong facilitates analysis of building footprints, communication network, and open ground. Different building typologies are identified taking into account the building’s structural configuration assessed through a rapid visual survey of more than 15% of total residential households. Slope map demarcates the landslide-prone area through discrete elevation modelling. A methodology incorporating several parameters e.g. building typology, slope angle, shear wave velocity characteristics, geomorphology, and the number of occupants in correlation with a physical measurement of vulnerability is presented and is applied to estimate the dimension of vulnerability. Additionally, MASW survey indicates lithology up to 30?m deep along with the existence of stiff soil and rocks at different depths whereas resonant frequency is identified to be in the range of 6–8?Hz through H/V ratio. Integrating all, it is observed that more than 60% of Shillong city falls under moderate to higher vulnerability and the rest is less vulnerable. 相似文献
90.
Bimal Kanti Paul 《The Professional geographer》2005,57(4):495-505
Following the devastating flood in 1998, the U.S. government proposed a Status of Forces Agreement (SOFA) to the Bangladesh government. Accepting the 1998 SOFA would have allowed entry of U.S. troops in Bangladesh without passports or visas and without requiring declaration of military hardware. This would have facilitated American forces support for relief operations and rehabilitation of disaster victims in the shortest possible time. Unfortunately, the Bangladesh government rejected the U.S. terms outlined in the 1998 proposal. A sample survey was conducted among Bangladeshi Americans to examine their opinions regarding the 1998 SOFA. Survey data reveals that slightly over 58 percent of the respondents supported signing the SOFA. Reasons for their support or opposition to the U.S. proposal are also presented. Statistical analyses suggest that whether respondents have studied or are currently studying in the United States emerged as the most significant factor associated with approval or disapproval of the 1998 SOFA. Implications of the study findings are also discussed. 相似文献