全文获取类型
收费全文 | 299篇 |
免费 | 13篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 32篇 |
大气科学 | 16篇 |
地球物理 | 115篇 |
地质学 | 82篇 |
海洋学 | 25篇 |
天文学 | 38篇 |
综合类 | 4篇 |
自然地理 | 6篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 17篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 17篇 |
2011年 | 15篇 |
2010年 | 11篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有318条查询结果,搜索用时 0 毫秒
311.
Anil Kumar Misra Anju Saxena Manish Yaduvanshi Ajai Mishra Yogendra Bhadauriya Alok Thakur 《Environmental Geology》2007,51(8):1361-1376
India is a vast country and is highly diversified in terms of natural resources and socio-economic setup. Moreover, its water
resources are unevenly distributed in space and time. With increasing population and increasing aspiration for improved standard
of living, there is an acute pressure on the demand and availability of water. Though the idea of interlinking of rivers is
not a new concept in India, it had rather persisted long back as much as in other countries of ancient civilization. National
Water Development Agency (NWDA) has given the real shape to the proposal of the interlinking of rivers of the country. In
India the river-linking project in a sensible and scientific manner will not only allow the prevention of the colossal wastage
of a vitally important natural resource, mitigate the flood and inundation by detaining flowing surface water of rainy seasons,
but also ensure availability of water to drier areas; combating both flood and drought simultaneously. Moreover, this project
will generate 34,000 MW of hydropower and irrigation of an additional 35 million hectares (135,135 square miles) of land.
Though linking of rivers may initially appear to be a costly proposition in ecological, geological, hydrological and economical
terms, in the long run the net benefits coming from it will far outweigh these costs or losses. However, in the absence of
any definite international legal framework, Bangladesh has raised objections against the project. This paper aims at looking
at this long-term plan, the project proposal, its involvement and impact not only on the states of India, India as a whole,
but also on its neighbouring nations which are linked with India through the waterways, and share the common climatic conditions
and economic status. 相似文献
312.
The generalized Rayleigh type surface waves are studied in a multilayered medium consisting of anisotropic poroelastic solid
layered stack beneath a fluid layer and overlying a heterogeneous elastic solid half-space. The heterogeneity, considered,
is of vertical type. The interface between solid layer and half-space is treated as an imperfect interface and suitable boundary
conditions are applied thereat. The technique of transfer matrix is used to obtain the dispersion equation in compact and
convenient form. Numerical results are obtained for particular models. The effects of anisotropy and heterogeneity on the
surface waves speed are discussed. 相似文献
313.
The steady‐forced and earthquake responses of SDF systems with a non‐linear fluid viscous damper (FVD) are investigated. The energy dissipation capacity of the FVD is characterized by the supplemental damping ratio ζsd and its non‐linearity by a parameter designated α. It is found that the structural response is most effectively investigated in terms of ζsd and α because (1) these two parameters are dimensionless and independent, and (2) the structural response varies linearly with the excitation intensity. Damper non‐linearity has essentially no influence on the peak response of systems in the velocity‐sensitive spectral region, but differences up to 14% were observed in the other spectral regions. The structural deformation is reduced by up to 25% when ζsd= 5%; and by up to 60% when ζsd= 30%. Non‐linear FVDs are advantageous because they achieve essentially the same reduction in system responses but with a significantly reduced damper force. For practical applications, a procedure is presented to estimate the design values of structural deformation and forces for a system with non‐linear FVD directly from the design spectrum. It is demonstrated that the earthquake‐induced force in a non‐linear FVD can be estimated from the damper force in a corresponding system with linear FVD, its peak deformation, and peak relative velocity; however, the relative velocity should not be approximated by the pseudo‐velocity as this approximation introduces a large error in the damper force. Finally, a procedure is presented to determine the non‐linear damper properties necessary to limit the structural deformation to some design value or the structural capacity for a given design spectrum. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
314.
315.
A ground motion selection procedure for enforcing hazard consistency and estimating seismic demand hazard curves 下载免费PDF全文
This paper develops a procedure to select unscaled ground motions for estimating seismic demand hazard curves (SDHCs) in performance‐based earthquake engineering. Currently, SDHCs are estimated from a probabilistic seismic demand analysis, where several ensembles of ground motions are selected and scaled to a user‐specified scalar conditioning intensity measure (IM). In contrast, the procedure developed herein provides a way to select a single ensemble of unscaled ground motions for estimating the SDHC. In the context of unscaled motions, the proposed procedure requires three inputs: (i) database of unscaled ground motions, (ii) I M , the vector of IMs for selecting ground motions, and (iii) sample size, n; in the context of scaled motions, two additional inputs are needed: (i) a maximum acceptable scale factor, SFmax, and (ii) a target fraction of scaled ground motions, γ. Using a recently developed approach for evaluating ground motion selection and modification procedures, the proposed procedure is evaluated for a variety of inputs and is demonstrated to provide accurate estimates of the SDHC when the vector of IMs chosen to select ground motions is sufficient for the response quantity of interest. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
316.
W. Mike Edmunds Ramasamy Jayakumar Anil Mishr Abdin Salih Soroosh Sorooshian Howard S. Wheater William Logan 《寒旱区科学》2013,5(1):0001-0005
The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas.
The primary aim has been to build a comprehensive global network to promote regional and international cooperation so as to increase
knowledge and improve management practices through the sharing of information. The G-WADI objectives and achievements
of the past 10 years are reviewed. A number of key initiatives have been implemented––the formation of five regional networks,
the creation of a central G-WADI web site, promotion of near-real-time rainfall distribution software enhanced by the inclusion
of satellite based precipitation estimations, as well as workshop and web-based activities on chemical and isotopic tracers
and on rain water harvesting. Two workshops on surface and on groundwater modeling, supported by publications have been held
in India and China. The Asian G-WADI network remains very active, but activities in the other three regions are developing (Africa,
Arab Region, Latin America and the Caribbean). 相似文献
317.
Parijat Roy Vysetti Balaram Anil Kumar Manavalan Satyanarayanan Thota Gnaneshwar Rao 《Geostandards and Geoanalytical Research》2007,31(3):261-273
Data on thirty-four minor and trace elements including all rare earth elements (REE) are reported for two kimberlitic international reference materials (SARM-39, MINTEK, RSA and MY-4, IGEM, Russia) by inductively coupled plasma-mass spectrometry (ICP-MS), some of them for the first time. Four digestion techniques (open acid, closed vessel acid, microwave and lithium metaborate fusion digestion) were used for the decomposition of samples for analysis by ICP-MS. Three other reference materials (USGS BHVO-1, CRPG BR-1 and ANRT UB-N) were analysed simultaneously using the same analytical methodology to assess the precision and accuracy of the determinations. The data obtained in this study compare well with working values wherever such values are available for comparison. Though open acid digestion was found to be very rapid, effective and convenient for the determination of several trace elements in kimberlitic samples, recoveries for heavy rare earth elements (HREE) were lower than the respective recoveries obtained by the other decomposition techniques used. The precision obtained was better than ± 6% RSD in the majority of cases with comparable accuracy. Chondrite-normalised plots of each RM for all the digestion techniques were smooth. The new data reported on the two kimberlitic reference materials make these samples useful for future geochemical studies of kimberlitic rocks. 相似文献
318.
GUPTA Pratibh BALAJI Raju PARANI M CHANDRA T S SHUKLA P KUMAR Anil BANDOPADHYAY Rajib 《海洋学报(英文版)》2015,34(8):73-82
Fifty-seven bacteria were isolated from Southern Ocean(Indian sector) water samples which were collected from different latitude and longitude of the ocean. All the isolates were able to grow at 4°C, 20°C, 37°C and tolerable Na Cl concentration up to 13.5%(w/v). 29 out of 57 isolates were identified using 16 S rDNA amplification and the sequences were submitted to National Center for Biotechnology Information(NCBI). All the isolates were classified by using Ribosomal Database Project(RDP) and found that isolates belongs to Proteobacteria and Bacteriodes. The average G+C content was 56.4%. The isolates were screened for the presence of extracellular enzymes, viz. amylase, catalase, urease, esterase, lipase and protease. The disc diffusion method is used to screen antibiotic production by the isolates against four pathogenic bacteria, viz. Salmonella typhimurium(NCIM 2501),Staphylococcus aureus(NCIM 2122), Bacillus subtilis(NCIM 2193), and Pseudomonas aeruginosa(NCIM 2036).Nine out of 29 were found to be antibiotic producer. 相似文献