全文获取类型
收费全文 | 147篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 13篇 |
大气科学 | 8篇 |
地球物理 | 17篇 |
地质学 | 89篇 |
天文学 | 24篇 |
综合类 | 2篇 |
自然地理 | 1篇 |
出版年
2022年 | 7篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 3篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
排序方式: 共有154条查询结果,搜索用时 15 毫秒
61.
Aquifer characteristics and its modeling around an industrial complex,Tuticorin, Tamil Nadu,India: A case study 总被引:3,自引:0,他引:3
Anthropogenic pollution of shallow groundwater resources due to industrial activities is becoming a cause of concern in the
east coastal belt of the state of Tamil Nadu, India. Integrated hydrogeological, geophysical and tracer studies were carried
out in the coastal region encompassing an industrial complex. The objective has been to gain knowledge of aquifer characteristics,
ascertaining groundwater movement and its flow direction, which would in turn reveal the possibility of contamination of groundwater
regime and its better management. The results of multi-parameters and model study indicate that the velocity of groundwater
flow ranges from 0.013 m/d to 0.22m/d in and around the industrial complex in upstream western part of the catchment and 0.026
m/d to 0.054m/d in the downstream eastern part, near the coast. These parameters are vital for the development of groundwater
management scheme. 相似文献
62.
63.
Improvement of groundwater quality due to fresh water ingress in Potharlanka Island, Krishna delta, India 总被引:1,自引:0,他引:1
Hydrochemical study had been carried out on the groundwater resources of Potharlanka Island, Krishna delta, India. Groundwater
samples were collected and analyzed at 42 sites in December 2001 and October 2006. A comparative study of hydrochemical data
indicates: groundwater is mildly alkaline with a pH of 7.0–8.2; electrical conductivity (EC) varies from 605 to 5,770 μS/cm
in December 2001, and 652–5,310 μS/cm in October 2006. More than 62% of the groundwater samples in 2006 have TDS value <2,000 mg/l,
which is within permissible limit of potable water, but 57% of the samples in 2001, are higher than the maximum permissible
limit. Extremely low HCO3/Cl and variable high Mg/Ca (molar ratios) had been indicated the transformation of the fresh groundwater aquifer systems
to saline in 2001. Groundwater of this Island is mainly classified as Na–Cl and mixed types. A high percentage of Na–Cl type
of these waters indicates the possibility of seawater ingression/intrusion process during 2001 and comparatively mixed water
type indicates the dilution activities of groundwater. Excessive withdrawal of groundwater has caused the increase of saline
water intrusion. Improvement of groundwater quality in this Island due to artificial recharge structures made by NGRI under
RGNDWM project and affects of the flood due to heavy rainfall of the months of September–October 2005 are discussed in this
paper. 相似文献
64.
Md. Surabuddin Mondal A. C. Pandey R. D. Garg 《Journal of the Indian Society of Remote Sensing》2008,36(1):69-76
Water is the most important natural resource which forms the core of the ecological system. The advent of remote sensing has
opened up new vistas in groundwater prospect evaluation, exploration and management. The groundwater resources of the study
area, Rishikesh region of Garhwal Himalayas, are under threat due to population pressure caused by expanding tourism in this
region. This entails sustainable and judicious use of this precious resource. The groundwater prospect evaluation in Rishikesh
region has been attempted based on hydrogeomorphological mapping of the area consisting of thematic maps of hydrogeomorphology,
geology, drainage, lineament, slope and relief using high resolution IRS-1C LISS III and PAN merged satellite images. The
Rishikesh region exhibits diverse hydrogeomorphological conditions where the groundwater regime is controlled mainly by topography
and geology. A probability-weighted approach has been applied during overlay analysis in ArcMap GIS environment. The overlay
analysis allows a linear combination of weights of each thematic map with respect to ground water potential. Good groundwater
prospects dominate in the area with more than 50% of the study area showing moderate to excellent potential. The study shows
that the remote sensing and geoinformatics techniques can be applied effectively for groundwater prospect evaluation. 相似文献
65.
The variation of temporal fractal dimension D2 (t) value may be well applied for understanding the future large earthquakes. In this present analysis the time series of inter-occurrence of earthquakes of consecutive hundred events window in Himalayan region is analyzed. We observed the variation in D2 (t) values in the range of 0.19 to 0.68 indicating the variation of clustering of events with respect to time. The multifractal nature of earthquakes is also investigated by plotting Dq(t) versus q. The result shows the temporal distribution of earthquakes have multifractal structure of definitive pattern rather than random pattern. 相似文献
66.
Anirban Mukhopadhyay Arun Mondal Sandip Mukherjee Dipam Khatua Subhajit Ghosh Debasish Mitra Tuhin Ghosh 《Journal of Earth System Science》2014,123(6):1349-1360
In the Himalayan states of India, with increasing population and activities, large areas of forested land are being converted into other land-use features. There is a definite cause and effect relationship between changing practice for development and changes in land use. So, an estimation of land use dynamics and a futuristic trend pattern is essential. A combination of geospatial and statistical techniques were applied to assess the present and future land use/land cover scenario of Gangtok, the subHimalayan capital of Sikkim. Multi-temporal satellite imageries of the Landsat series were used to map the changes in land use of Gangtok from 1990 to 2010. Only three major land use classes (built-up area and bare land, step cultivated area, and forest) were considered as the most dynamic land use practices of Gangtok. The conventional supervised classification, and spectral indices-based thresholding using NDVI (Normalized Difference Vegetation Index) and SAVI (Soil Adjusted Vegetation Index) were applied along with the accuracy assessments. Markov modelling was applied for prediction of land use/land cover change and was validated. SAVI provides the most accurate estimate, i.e., the difference between predicted and actual data is minimal. Finally, a combination of Markov modelling and SAVI was used to predict the probable land-use scenario in Gangtok in 2020 AD, which indicted that more forest areas will be converted for step cultivation by the year 2020. 相似文献
67.
Fractal study of seismicity in order to characterize the various tectonic blocks of North-east Himalaya,India 总被引:1,自引:1,他引:0
Three major projects initiated by the European Commission within its 7th Framework Programme that have studied the weather phenomena and their projections to the future in relation to their impacts and implications to the European transport systems have recently been concluded. All of the transport modes were covered, as well as all of the critical phenomena present within the European area. The three projects (that ran from 2009 and 2012) are as follows: (1) EWENT (Extreme Weather impacts on European Networks of Transport—www.ewent.vtt.fi); (2) ECCONET (Effects of climate change on the inland waterway networks—www.ecconet.eu); (3) WEATHER (Weather Extremes: Assessment of Impacts on Transport and Hazards for European Regions—www.weather-project.eu). In this Foreward to the Special Issue on “Vulnerability of Transportation to Extreme Weather and Climate Change,” the key results of the above three projects are addressed concisely, offering the reader a broader view of their findings; since some of these are enveloped in the research papers hosted in this volume, they will not be covered in detail. However, the rich output of these projects in the form of “Project Deliverables” and “Reports” is also an important source of information on the findings and results from these three projects which are publicly available on the projects’ Web sites. The purpose of this Foreward is to bring to the attention of the interested reader these sources and overview briefly some of the projects’ outcomes. Also, a short comparative discussion on selected findings is made, outlining agreements and disagreements between the projects. 相似文献
68.
T. K. Biswal V. Thirukumaran Kamleshwar Ratre Krishanu Bandyapadhaya K. Sundaralingam Amit Kumar Mondal 《Journal of the Geological Society of India》2010,75(1):128-136
The E-W running Salem-Attur shear zone demarcates the tectonic boundary between Archaean Dharwar Craton in the north and Proterozoic
Southern granulite terrane in the south. This study reveals that the shear zone is a low angle thrust. The thrust zone is
around 10 m thick and it merges with the main shear zone along the strike. The thrust is developed on charnockite near Odyarpatti,
which is retrograded into schists. Further, it is marked by gently dipping mylonitic foliation and subhorizontal lineation.
The S-C fabric, mantled porphyroclasts and intragranular faults indicate northeasterly slip along the thrust. Recumbent shear
folds SF1 are developed within the thrust zone. The thrust has been folded by late stage F2 fold which has brought variation in the orientation of the mylonitic foliation from subhorizontal to vertical attitude; the
mylonitic lineations have been rotated to subvertical orientation also. Additionally, the F2 crenulations and shear cleavages and intersection lineations are superimposed on the mylonitic fabric. Thrusting along the
Salem-Attur shear zone is probably the cause for upliftment of the charnockites to the upper crust. Post-upliftment stage
has witnessed brittle deformation in the form of development of shear fractures in NNE-SSW and E-W directions. Pseudotachylites
are emplaced along these fractures. 相似文献
69.
Infrastructure and communication facilities are repeatedly affected by ground deformation in Gharwal Himalaya, India; for effective remediation measures, a thorough understanding of the real reasons for these movements is needed. In this regard, we undertook an integrated geophysical and geotechnical study of the Salna sinking zone close to the Main Central Thrust in Garhwal Himalaya. Our geophysical data include eight combined electrical resistivity tomography (ERT) and induced polarization imaging (IPI) profiles spanning 144–600 m, with 3–10 m electrode separation in the Wenner–Schlumberger configuration, and five micro-gravity profiles with 10–30 m station spacing covering the study region. The ERT sections clearly outline the heterogeneity in the subsurface lithology. Further, the ERT, IPI, and shaliness (shaleyness) sections infer the absence of clayey horizons and slip surfaces at depth. However, the Bouguer gravity analysis has revealed the existence of several faults in the subsurface, much beyond the reach of the majority of ERT sections. These inferred vertical to subvertical faults run parallel to the existing major lineaments and tectonic elements of the study region. The crisscross network of inferred faults has divided the entire study region into several blocks in the subsurface. Our studies stress that the sinking of the Salna village area is presently taking place along these inferred vertical to subvertical faults. The Chamoli earthquake in March 1999 probably triggered seismically induced ground movements in this region. The absence of few gravity-inferred faults in shallow ERT sections may hint at blind faults, which could serve as future source(s) for geohazards in the study region. Soil samples at two sites of study region were studied in a geotechnical laboratory. These, along with stability studies along four slope sections, have indicated the critical state of the study region. Thus, our integrated studies emphasize the crucial role of micro-gravity in finding fine subsurface structure at deeper depth level; supported by ERT and IPI at shallow depth intervals, they can satisfactorily explain the Salna sinking zone close to Lesser Himalaya. The geotechnical studies also lend support to these findings. These integrated studies have yielded a better understanding of the mass-wasting mechanism for the study region. 相似文献
70.
Detection of ionospheric perturbation due to a soft gamma ray repeater SGR J1550-5418 by very low frequency radio waves 总被引:1,自引:0,他引:1
Sushanta K. Mondal Sandip K. Chakrabarti Sudipta Sasmal 《Astrophysics and Space Science》2012,338(2):259-264
The properties of cylindrical and spherical dust acoustic (DA) solitary and shock waves in an unmagnetized electron depleted
dusty plasma consisting of inertial dust fluid and ions featuring Tsallis statistics are investigated by employing the reductive
perturbation technique. A Korteweg-de Vries Burgers (KdVB) equation is derived and its numerical solution is obtained. The
effects of ion nonextensivity and dust kinematic viscosity on the basic features of DA solitary and shock waves are discussed
in nonplanar geometry. It is found that nonextensive nonplanar DA waves behave quite differently from their one-dimensional
planar counterpart. 相似文献