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51.
52.
江西永豐縣南,古縣至瑤田間之梁坊橋附近,有一變形礫岩層,恰位於走向北10度東及北80度东兩逆斷層啣接處。該礫岩層中之礫石,多為扁平橢圓形,其長軸兩端逐漸尖化,外附絲澤、臘狀、光滑表皮,並有新生之雲母片及長纖維狀物質,於此光滑面上,常具深刻水平擦痕。這些變形礫石,受外力變形後,共長軸近於東西,扁平面平行於北80度東之斷層面舆附近岩層之片理。垂直變形礫石a,b,c三軸及膠結物質延長方向,分製薄片,在顯微鏡下觀察,其膠結物為灰白色雲母及許多無光性之黑色物質,呈顯著之流紋構造,內含大小不一之眼球狀石英粒等;石英礫石內之石英晶體,均具極强之波浪消光,於晶體四周,圍繞密擠再結晶之小型石英粒,而示標準磨碎構造。晶體本身含有無數極小之氣孔或包體,並作一定方向排列,而成變形紋理,平行於扭應面;在石英岩礫石內,石英粒均沿一定方向延長,並按其大小作帶狀排列。礫石內部,擁有極複雜之節理舆顯明之断層,這些事實象微着强烈的外力作用。根據弗氏旋轉台再結晶石英粒。軸及雲母底面等之統計舆分析,得知其晶體排列恆受扭應力支配。 相似文献
53.
Results of organic carbon, total nitrogen, amino acid and hexosamine analyses of samples collected during time-series sediment trap investigations in the Arabian Sea are presented. Samples were taken over a period of
years at two depths at each of three locations in the western, central and eastern part of the basin. Seasonal changes in amino acid contents and their spectral distributions show that degradation of organic matter in the water column is reduced during the monsoons, which are the high-flux periods in the western and central Arabian Sea. At the eastern site more degraded material of possibly recycled marine or terrestrial origin reaches the traps during the late summer peak fluxes. The results of hexosamine analyses suggest that bacterial biomass is relatively enriched on particles sinking in the water column and, to a larger extent, at the sediment-water interface. Decomposition between intermediate and deep water results in a loss of 30–40% of total organic carbon and more than 40% of amino acids. Comparison of the measured accumulation rates of organic carbon in sediment traps with those of organic carbon preserved in sediments show that more than 85% is lost before final burial in the sediments. Organic matter preservation in the Arabian Sea is higher than the average for the open ocean; this maybe due to the abundance of refractory organic matter of recycled marine or terrestrial origin. 相似文献
54.
Naduvilaveettil Sukumaran Kalesh Chenycherri House Sujatha S. Muraleedharan Nair 《Journal of Oceanography》2001,57(1):29-36
Information on the distribution of dissolved Folin phenol active substances (FPAS) such as tannin and lignin in the seawater along the west coast of India is provided. Notable amounts of FPAS (surface concentrations: 80 g/l to 147 g/l and bottom concentrations: 80 g/l to 116 g/l) were detected in the seawater along the coast. The distribution pattern brings about a general depth-wise decrease. A seaward decrease was observed in the southern stations whereas reverse was the case in northern stations. A significant negative correlation was observed between FPAS concentration and dissolved oxygen in sub-surface samples. The appreciable amounts of FPAS detected in the coastal waters indicate the presence of organic matter principally originating from terrestrial (upland and coastal marsh) ecosystems in the marine environment. In this context, they may be used as tracers to determine the fate of coastalborn dissolved organic matter in the ocean and to determine directly the relationship between allochthonous and autochthonous organic matter. 相似文献
55.
Yuling Wu Udaysankar S. Nair Roger A. PielkeSr. Richard T. McNider Sundar A. Christopher Valentine G. Anantharaj 《Boundary-Layer Meteorology》2009,133(3):367-389
Prior numerical modelling studies show that atmospheric dispersion is sensitive to surface heterogeneities, but past studies
do not consider the impact of a realistic distribution of surface heterogeneities on mesoscale atmospheric dispersion. While
these focussed on dispersion in the convective boundary layer, the present work also considers dispersion in the nocturnal
boundary layer and above. Using a Lagrangian particle dispersion model (LPDM) coupled to the Eulerian Regional Atmospheric
Modeling System (RAMS), the impact of topographic, vegetation, and soil moisture heterogeneities on daytime and nighttime
atmospheric dispersion is examined. In addition, the sensitivity to the use of Moderate Resolution Imaging Spectroradiometer
(MODIS)-derived spatial distributions of vegetation characteristics on atmospheric dispersion is also studied. The impact
of vegetation and terrain heterogeneities on atmospheric dispersion is strongly modulated by soil moisture, with the nature
of dispersion switching from non-Gaussian to near-Gaussian behaviour for wetter soils (fraction of saturation soil moisture
content exceeding 40%). For drier soil moisture conditions, vegetation heterogeneity produces differential heating and the
formation of mesoscale circulation patterns that are primarily responsible for non-Gaussian dispersion patterns. Nighttime
dispersion is very sensitive to topographic, vegetation, soil moisture, and soil type heterogeneity and is distinctly non-Gaussian
for heterogeneous land-surface conditions. Sensitivity studies show that soil type and vegetation heterogeneities have the
most dramatic impact on atmospheric dispersion. To provide more skilful dispersion calculations, we recommend the utilisation
of satellite-derived vegetation characteristics coupled with data assimilation techniques that constrain soil-vegetation-atmosphere
transfer (SVAT) models to generate realistic spatial distributions of surface energy fluxes. 相似文献
56.
A baseline study of trace metals in a coral reef sedimentary environment,Lakshadweep Archipelago 总被引:3,自引:1,他引:2
Anu Gopinath S. M. Nair N. C. Kumar K. V. Jayalakshmi D. Pamalal 《Environmental Earth Sciences》2010,59(6):1245-1266
Surficial and core samples collected from the sedimentary microenvironments of Lakshadweep Archipelago were analysed for their
trace metal contents. The synoptical relations in spatial distributions with respect to environmental conditions such as pH,
organic carbon and sediment texture were inter-correlated. Some of the metals exhibited good correlations with Fe/Mn, which
reflect their similarity in distribution rather than anthropogenic enrichment. Inter-relating the variations in metal—pH relationships
with metal—organic carbon, in general, those which exhibited positive correlations with pH, displayed negative interactions
with organic carbon content and vice versa. Comparatively, higher values of Fe in the mangrove area of one of the islands
highlight the possibility of precipitation of Fe as iron sulphides, which are common in mangrove ecosystem. Based on the contamination
factors for Pb, Zn and Cd, as well as the geo-accumulation index of Cd, it can be generalised that some of the islands remain
polluted with respect to these elements. An evaluation based on pollution load index shows that none of the islands surveyed
for this study posed a serious threat in trace metal pollution. Bray Curtis similarity index was computed to find out the
similarity among metals/islands, using non-transformed data of metal concentrations. Group linkage clustering technique was
used for drawing dendrograms to show the similarity among them. 相似文献
57.
This work addresses the mechanisms that leads to an early onset of monsoon over Andaman Sea but advances further rapidly (slowly) to the Indian mainland resulting in the early (delayed) onset over Kerala. The upper tropospheric temperature, production of kinetic energy (KE) and outgoing long wave radiation (OLR) from the month of May till onset over Kerala are analysed for two delayed onset years (1997, 1995) and two early onset years (2004, 1990). It is observed that the maximum temperature over Tibetan plateau (TP), an increase in the production of KE and strong equatorial convection in early May, is associated with early onset over Andaman Sea. However, when there is a lull in advance of monsoon after the early onset over Andaman Sea, shifting of the warm region south of TP, weak production of KE in the lower troposphere and convective region shifting to Western Pacific resulted in the delayed onset over Kerala in 1997 and 1995. During the early onset years viz. 2004 and 1990, the warm region moving westwards, high production of KE extending to mid troposphere and deep convection moving westwards in the north Indian Ocean (10–15°N) is noticed. 相似文献
58.
59.
A S K Nair G Sankar S Nalina Kumar 《Journal of the Indian Society of Remote Sensing》1993,21(3):151-156
The coastal zone of Kerala with moderate energy, monsoonal-storm-dominated wave climate, together with a microtidal range, falls under the major tectonic class of the Amerotrailing edge coasts. In order to have an effective management of this coastal zone, one requires detailed information on various types of coastal landforms and the related processes acting on them. Coastal inlets are one among such landforms, which are relatively short and narrow tidal channels connecting bays and lagoons to the ocean. Coastal inlets and the related landforms form an important type of coastal feature. An examination of coastal maps from any area in the world will reveal that coastal inlets are of migratory and offset in nature. In the present study the migration pattern and offset behaviour of some of the inlets of Kerala coast have been examined using IRS-IA LISS II data and Survey of India topographic sheets. The study reveals that geocoded IRS-IA LISS II data could provide accurate geometrical information which may considerably minimise the field check. 相似文献
60.
Summary An infinite cylinder is assumed to have a small ridge on the surface. The effect of the ridge on the eigenfrequencies of flute mode of oscillation is obtained in the linear approximation. The usefulness of these results in seismological problems is indicated. 相似文献