全文获取类型
收费全文 | 246篇 |
免费 | 4篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 30篇 |
地球物理 | 50篇 |
地质学 | 113篇 |
海洋学 | 1篇 |
天文学 | 44篇 |
综合类 | 5篇 |
自然地理 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 13篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 17篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有256条查询结果,搜索用时 15 毫秒
31.
Chinmay Mallik S. Venkataramani Shyam Lal 《Asia-Pacific Journal of Atmospheric Sciences》2012,48(2):171-180
Continuous measurements of SO2, NOx and O3 along with sampling based measurements of CO, CH4, NMHCs and CO2 were carried out during May, 2010 at Ahmedabad. The diurnal variations of SO2 in ambient air exhibited elevated values during the night and lower levels during the sunlit hours. The mean concentration of SO2 during the study period was 0.95 ± 0.88 ppbv. However, the ambient SO2 exceeded 17 ppbv in the night of 20 May, 2010. On the same day, tropospheric columnar SO2 from OMI showed almost 350% increase corroborating the surface observations over an extended height regime. This was also the highest columnar value of SO2 during the summer of 2010. Columnar loadings were also found to be high for formaldehyde, precipitable water vapor and aerosol optical depth on 20 May. Elevated concentrations were also recorded for other trace gases like NO2 and O3. Analysis of related data of trace gases indicated characteristics of fresh emissions with dominant contributions from mobile sources during the study period. However, SO2/NO2 ratio of 0.36 during the event period on 20th May connotes non-local influences. Analyses of meteorological parameters suggest combined impacts of transport and inversion causing higher levels of SO2 and other pollutants during 20?C21 May. Episodes of such enhancements may perturb chemical and radiative balance of the atmosphere. 相似文献
32.
Shovan Lal Chattoraj Santanu Banerjee P. K. Saraswati 《Journal of the Geological Society of India》2009,73(4):567-574
Glauconitic minerals are considered as one of the valuable input parameters in sequence stratigraphic analysis of a basin.
In the present study glauconitic minerals are reported from subtidal green shale facies in the lower part of the Late Paleocene-Early
Eocene Naredi Formation of western Kutch. On the basis of the foraminiferal assemblage the glauconite bearing beds are interpreted
to have formed in a mid shelf depositional settings of an unstable marine conditions. XRD studies confirm the glauconite mineralogy
of the green pellets and provide an estimation of glauconite maturity. Textural attributes of the glauconites confirm their
derivation by different degrees of alteration of precursor feldspar grains. Because of the authigenic origin and autochthonous
nature, these glauconites hold promise for understanding sequence stratigraphy of the Palaeogene succession of the western
Kutch. 相似文献
33.
The evolution of east coast of India sis discussed within the ambit of clearly identifiable four major tectonic stages which
had a profound effect in shaping the tectonic grain of the east coast basins. The evolutionary process began with rift related
crustal extension between India and Sri Lanka as a consequence of Africa-Antarctica rifting and development of Natal Basin.
An arm of this rift led to initial extension in the Cauvery Basin and failed. Later, the India-West Australia rift propagated
further in southwesterly direction initiating Mahanadi and Krishna-Godavari Basins. This extension was an oblique one with
Nayudupeta high acting as pivot. The oblique extension followed by asymmetric seafloor spreading developed transpression along
India-Sri Lanka and Antarctica junction, resulting in a NNW-SSE trending transcurrent fault along which Antarctica moved southward.
Subsequently, entire east coast evolved through a more or less uniform post rift stage. 相似文献
34.
Devendra Lal 《Meteoritics & planetary science》2008,43(11):1909-1909
35.
Analysis of fractures inferred from DBTM and remotely sensed data for groundwater development in godavari sub-watershed, Giridih, Bihar 总被引:2,自引:2,他引:0
Ashok Kumar Savita Tomar Lal Bihari Prasad 《Journal of the Indian Society of Remote Sensing》1999,27(2):105-114
Godavari sub-watershed is a part of buried pediplain developed over ‘Chotanagpur’ granite gneiss. Aquifer is unconfined in nature and groundwater occurs under water table condition. In the study area, groundwater is being exploited only through dugwells which are not capable of sustaining long duration pumping. Groundwater exploration involves the investigation of depth and nature of weathered and fractured horizon. To understand the groundwater storage and retrieval in the area, the basement topography derived from Digital Basement Topography Modelling (DBTM), the lineaments identified on remotely sensed data and geohydrological and physiographic data have been analysed. From DBTM, fracture zones have also been inferred. Lineaments (probable fractures) identified with the help of remotely sensed data are linear features representated on a planner surface. Lineaments in the area are subtle in expression due to deeply buried pediplian. Correlation of lineaments with DBTM reveals that a few lineaments/fractures are deep seated and a few have no sub-surface extensions. Also some sub-surface fractures inferred from DBTM have no expressions on the image. Attempt has been made to delineate more authentic lineaments/fractures with the help of remotely sensed data and DBTM. Correlation of probable fractures inferred from remotely sensed data and fracture zones inferred from DBTM indicated that 40 per cent of lineaments seems to be real fractures. Higher correlation may be achieved where lineaments are prominent and reproducible. It has also been observed that those lineaments which correlate with the fracture zones inferred from DBTM, are also not completely traceable in their linear extent. The exaggeration in length of lineaments may be due to subtle nature of lineaments. Correlation shows that remotely sensed lineaments are improtant for groundwater exploration and its authenticity can be further ascertained with DBTM. 相似文献
36.
Raghavendra Vishnu Tadivaka Bhanu Priyanka Paruchuri Sridhar Miriyala Padma Raju Koppireddi Venkata Ratnam Devanaboyina 《Acta Geophysica》2017,65(4):777-784
The performance and measurement accuracy of global navigation satellite system (GNSS) receivers is greatly affected by ionospheric scintillations. Rapid amplitude and phase variations in the received GPS signal, known as ionospheric scintillation, affects the tracking of signals by GNSS receivers. Hence, there is a need to investigate the monitoring of various activities of the ionosphere and to develop a novel approach for mitigation of ionospheric scintillation effects. A method based on Local Mean Decomposition (LMD)–Detrended Fluctuation Analysis (DFA) has been proposed. The GNSS data recorded at Koneru Lakshmaiah (K L) University, Guntur, India were considered for analysis. The carrier to noise ratio (C/N0) of GNSS satellite vehicles were decomposed into several product functions (PF) using LMD to extract the intrinsic features in the signal. Scintillation noise was removed by the DFA algorithm by selecting a suitable threshold. It was observed that the performance of the proposed LMD–DFA was better than that of empirical mode decomposition (EMD)–DFA. 相似文献
37.
Geotectonics - Study of morphometric parameters such as stream length (Lu) and stream length ratios (Rl), bifurcation ratio (Rb), drainage density (D), form factor (Rf), circularity ratio (Rc),... 相似文献
38.
Knowledge of seasonal variation in soil structural and related properties is important for the determination of critical periods during which soil is susceptible to accelerated erosion and other degradative processes. The purpose of this research was to evaluate the magnitude of seasonal variations in selected soil and deposited sediment properties in relation to soil erodibility for a Miamian silt-loam soil (Typic Hapludalf) in central Ohio. Erosion plots (USLE-type) were established on a 4·5% slope and maintained under bare, ploughed conditions from 1988 to 1991. Particle size distribution, bulk density(ρb), percentage water stable aggregates (WSA), soil organic carbon (SOC), and total soil nitrogen (TSN) of both soil and sediment samples were monitored between Autumn 1989 and Spring 1991. The soil and sediment particle size distributions followed no clear seasonal trends. Soil ρb increased following tillage (1·20 Mg m−3) and was highest (1·45 Mg m−3) during the autumn owing to soil slumping and consolidation upon drying. Low winter and spring values of ρb and %WSA (20–50% lower than in autumn) were attributed to excessive wetness and freeze–thaw effects. Both SOC and soil TSN contents progressively declined (from 2·18 to 1·79% and 1·97 to 1·75 g kg−1, respectively) after ploughing owing to maintenance of plots under bare, fallow conditions. Spring highs and autumn lows of sediment SOC (3·12 vs. 2·44%) and TSN (2·70 vs. 1·96 g kg−1) contents were a result of the combined effects of soil microbial activity and rainfall erosivity. Soil properties such as bulk density, SOC and WSA, which vary seasonally, can potentially serve as predictors of seasonal soil erodibility, which, in turn, could improve the predictive capacity of soil erosion prediction models. © 1998 John Wiley & Sons, Ltd. 相似文献
39.
Bacterial biosurfactants can be an ecofriendly and advanced technology for remediation of heavy metals and co-contaminated soil 总被引:1,自引:0,他引:1
A. J. Das S. Lal R. Kumar C. Verma 《International Journal of Environmental Science and Technology》2017,14(6):1343-1354
Environmental pollution due to heavy metals has become a significant drawback as a result of their ecotoxicity. Hence, their remediation is of pressing concern. Many technologies are planned for their remediation; however, most of them are highly expensive and result in incomplete removal of contaminants. So, massive attention has paid to the event and application of the latest biologically techniques, that is effective in remedy and cost, not harming the prevailing surroundings. Hence, application of biosurfactant in heavy metal remediation is one among the recent ecofriendly technique. The present review critically highlights bacterial biosurfactants as a best alternative technique for heavy metals remediation. The review also emphasizes that bacterial biosurfactants can open up a new vista in remediation of metal-contaminated soil. 相似文献
40.
O. P. Pandey Priyanka Tripathi Nimisha Vedanti D. Srinivasa Sarma 《Pure and Applied Geophysics》2016,173(7):2455-2471