全文获取类型
收费全文 | 103篇 |
免费 | 3篇 |
专业分类
测绘学 | 21篇 |
大气科学 | 10篇 |
地球物理 | 11篇 |
地质学 | 46篇 |
海洋学 | 9篇 |
天文学 | 8篇 |
综合类 | 1篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有106条查询结果,搜索用时 15 毫秒
71.
Systemic analysis of soil microbiome deciphers anthropogenic influence on soil ecology and ecosystem functioning 总被引:1,自引:0,他引:1
S. Gupta M. Kumar J. Kumar V. Ahmad R. Pandey N. S. Chauhan 《International Journal of Environmental Science and Technology》2017,14(10):2229-2238
Soil is a complex ecosystem with defined microbial community signatures, modulated by the interaction between biotic and abiotic factors. Amidst biotic factors, land usage have significant impact onto the soil microbial structure and ecosystem functioning. In the current study, metagenomic approach was used to decipher effect of hospital settings on soil microbiome structure and physiological functions. Physico-chemical properties analysis revealed that key elements for maintenance of soil microflora, such as organic carbon, nitrogen, phosphorus and sulfur were relatively diminished within hospital soil, compared to garden soil. Comparative microbial diversity analysis with 97,315 SSU rRNA gene sequences generated from both the soil samples highlight relatively low microbial diversity, with an enrichment for Acidobacteria and Bacteroidetes and decreased Proteobacteria/Acidobacteria ratio. Comparative shotgun metagenome sequence analysis further revealed a shift in the physiological role of soil microbiomes with change in soil usage. Genes for carbohydrate, sulfur, potassium and nitrogen metabolism were significantly (q value <0.05) higher in the garden soil; while the genes for phage, plasmid DNA, transposon and aromatic compound metabolism were significantly enriched within hospital soil. Thus, the current study highlights a correlation between soil biochemistry and microbial ecology based on land usage. 相似文献
72.
Udit Shankar Dasgupta Vinay Bhushan Chauhan 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(3):247-256
The present study investigates the influence of spatial variability of soil properties on the lateral thrust and failure surface of a 6?m high frictionless rigid earth retaining wall in active condition. The drained friction angle of the soil is modelled as a log-normal anisotropic random field in two dimensions, using the Cholesky decomposition technique. The effect of horizontal and vertical scale of fluctuation is observed on the lateral thrust. The failure surface in the backfill is found to be more or less similar for different combinations of spatial variability in vertical and horizontal directions. Monte-Carlo simulation technique is used to compute the probability of failure and to obtain the worst-case spatial variability configuration. 相似文献
73.
Mountain ecosystems are relatively more vulnerable to climate change since human induced climate change is projected to be higher at high altitudes and latitudes. Climate change induced effects related to glacial response and water hazards have been documented in the Himalayas in recent years, yet studies regarding species’ response to climate change are largely lacking from the mountains and Himalayas of Nepal. Changes in distribution and latitudinal/altitudinal range shift, which are primary adaptive responses to climate change in many species, are largely unknown due to unavailability of adequate data from the past. In this study, we explored the elevational distribution of butterflies in Langtang Village Development Committee (VDC) of Langtang National park; a park located in the high altitudes of Nepal. We found a decreasing species richness pattern along the elevational gradient considered here. Interestingly, elevation did not appear to have a significant effect on the altitudinal distribution of butterflies at family level. Also, distribution of butterflies in the area was independent of habitat type, at family level. Besides, we employed indicator group analysis (at family level) and noticed that butterfly families Papilionidae, Riodinidae, and Nymphalidae are significantly associated to high, medium and low elevational zone making them indicator butterfly family for those elevational zones, respectively. We expect that this study could serve as a baseline information for future studies regarding climate change effects and range shifts and provide avenues for further exploration of butterflies in the high altitudes of Nepal. 相似文献
74.
O. S. Chauhan B. S. Sukhija A. R. Gujar P. Nagabhushanam A. L. Paropkari 《Geo-Marine Letters》2000,20(2):118-122
Down-core variations in illite, chlorite, smectite and kaolinite (the major clays) in two 14C-dated cores collected along the SW continental margin of India show that illite and chlorite have enhanced abundance during
20–17, 12.5, 11–9.5, and 5–4.8 ka b.p., whereas smectite accumulation is higher between 17 and 12.5, and after 9 ka b.p. The climate may have been predominantly arid at 17 (20–17), 12.5, 10.5 (11–9.5), and 4.8 ka b.p. The first three dates correspond to the last glacial maximum, Bolling-Allerod, and Younger Dryas events, respectively. The
SW monsoon was variable between 17 and 15 ka b.p., and it was more stable and intense after the Younger Dryas until about 6 ka b.p.
Received: 2 December 1999 / Revision accepted: 11 April 2000 相似文献
75.
Vishal Chauhan O.P. Singh Vinod Kushwah Vikram Singh Birbal Singh 《Journal of Geodynamics》2009,48(2):68-74
Employing a three-component search coil magnetometer (f = 0.01–30 Hz) the ultra-low-frequency (ULF) magnetic field observations have been taken in a noise free rural site at Bichpuri, Agra, India since 20 April 2007. We have analysed 7 months of night time data from 01 May to 30 November 2007. The data show seven occurrences of ULF bursts with periods ranging from a few minutes to an hour in a wide frequency range up to 15 Hz. The occurrence of such ULF bursts has been statistically analysed. The polarization parameter analysis shows that two of these bursts occurred from sources in the ionosphere and magnetosphere (Z/X < 1). It is further seen that four bursts correlated very well with some regional earthquakes (M > 4.5), which occurred at distances less than 628 km from the observation site at Agra. In some cases the bursts occurred 1–3 days prior to the main shocks.Since earthquakes are also known to perturb the ionosphere, we have analysed total electron content (TEC) data obtained from a GPS receiver stationed at Agra since June 2006. Analysis of the data for the same period as the magnetic field observations shows that there existed TEC anomalies on all the days when ULF bursts occurred. The TEC anomalies show enhancement and depletion in the data in all cases. While the mechanisms of the ULF and TEC anomalies are not well known, it is expected that the ULF bursts occurred due to microfracturing of the earth's crust during stress accumulation and that the TEC anomalies occurred as a result of the electric field induced in the ionosphere during such processes. 相似文献
76.
Shivani Chauhan Mukta Sharma M.K. Arora N.K. Gupta 《International Journal of Applied Earth Observation and Geoinformation》2010
In the present study, Artificial Neural Network (ANN) has been implemented to derive ratings of categories of causative factors, which are then integrated to produce a landslide susceptibility zonation map in an objective manner. The results have been evaluated with an ANN based black box approach for Landslide Susceptibility Zonation (LSZ) proposed earlier by the authors. Seven causative factors, namely, slope, slope aspect, relative relief, lithology, structural features (e.g., thrusts and faults), landuse landcover, and drainage density, were placed in 42 categories for which ratings were determined. The results indicate that LSZ map based on ratings derived from ANN performs exceedingly better than that produced from the earlier ANN based approach. The landslide density analysis clearly showed that susceptibility zones were in close agreement with actual landslide areas in the field. 相似文献
77.
The present investigation aims to optimize dose and pattern of distillery effluent for sugarcane irrigation. The postmethanated distillery effluent (PMDE) was recorded to have significant amount of micro‐ (Na, Zn, Fe) and macro‐ (Ca, Mg, N‐NO3, P, K, S–SO) nutrients and so was utilized for sugarcane irrigation. Lysimetric studies were conducted to assess the impact of PMDE on sugarcane productivity with different concentrations (50 and 75%) and irrigation patterns (intermittent and pre‐sowing). The intermittent pattern of ferti‐irrigation with 50 and 75% effluent dose for sugarcane crop was found to enhance the growth and quality parameters of crop without impairing the groundwater quality. Results were more pronounced with 75% intermittent irrigation as the percent increase with respect to control for plant length, cane girth, cane weight, number of internodes per cane, dry matter accumulation, juice extraction, sucrose content, and available sugar were 28.0, 42.5, 14.6, 40.2, 54.4, 18.9, 44.9, 57.9, and 50.0%, respectively. It is suggested that PMDE can be used as an alternative of fresh water irrigation and also as a fertilizer for sugarcane, provided that the effluent quality and sugarcane quality is continuously monitored to avoid any contamination. 相似文献
78.
Over the last four decades exploitation of natural resources to meet increasing societal demands for land based products has
caused significant changes in land use and land cover not only in nature’s best gifted regions but also environmentally sensitive
arid regions. Through digital interpretation of IRS LISS-III data of 2004 supported with field survey, the present land use
map of Jhunjhunun district of arid Rajasthan has been prepared. Agriculture is the dominant land use constituting 84% (including
38% irrigated cropland) area. The land use changes over time and space are worked out by comparing with Landsat 2 MSS data
of 1975 and Land use/land cover map of 1988–89. These changes are correlated by analyzing historical land use and cropping
pattern data from 1957–58 to 2004–05. The region witnessed record increase in irrigated area but sharply depleted ground water
and rendered hectares of irrigated double cropland into dry land agriculture. Strategies and technologies are suggested for
sustainable use and management of different category of land. 相似文献
79.
80.
P. V. Nagamani Rajesh Shikhakolli Prakash Chauhan 《Journal of the Indian Society of Remote Sensing》2011,39(1):117-126
Quantitative assessment of chlorophyll-a concentration and its variability is an important input for the oceanic primary productivity modeling and also a key parameter
in the global carbon cycle studies. This present work is focused to understand the spatial and temporal variability of phytoplankton
in the Bay of Bengal (BOB) during winter monsoon season of October 1999 to March 2000 using Ocean Colour Monitor (OCM) sensor
onboard OCEANSAT-1 satellite. Daily chlorophyll-a images from OCM sensor were used in the study. Efforts were also put to study the correlation between chlorophyll-a concentrations; NOAA-AVHRR derived Sea Surface Temperature (SST) and QuickSCAT scatterometer derived wind stress data. Analysis
of the chlorophyll-a images shows the presence of extensive phytoplankton blooms during mid December 1999 to early January 2000 in the western
part of BOB. The bloom dominated regions also exhibit reduced SST (∼24–27°C) and enhanced wind stress indicating upwelling
processes leading nutrient entrainment in the upper column of the sea surface. Apart from this, higher phytoplankton biomass
associated with the fresh water reverine plumes has also been observed. During October 1999 a super cyclone was active in
the BOB, as increase in the productivity was observed in the early November 1999 images of OCM data due to the cyclone induced
churning of the water column. 相似文献