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931.
地质矿产资源是经济和社会可持续发展的保障。为适应经济和社会的可持续发展,本文对贵州的地质矿产调查、勘查、研究和管理提出几点建议:进一步加强贵州省地质矿产勘查工作投入;矿产勘查工作的重点是“攻深找肓”、“探边填空”和“打弱挖潜”;扩大服务领域,使地矿工作与贵州经济和社会发展紧密结合。 相似文献
932.
Grain size and mineral composition of core sediments were used to investigate influences of various terrestrial and marine conditions, which have prevailed on the southwestern Black Sea shelf during the Holocene. Siliciclastic mud with small amounts of sand and gravel from nearby coastal hinterland is the principal sediment type, whereas sediments deposited near the shelf edge and the Istanbul Strait and off the Duru Lake (a paleo-river mouth) constitued large quantities of sand and gravel of both biogenic and terrigenic origin. Variable amounts of aragonite, 1 nmmicas, quartz, feldspars, calcite and dolomite constitute the dominant non-clay minerals in bulk sediments. The clay mineral assemblage in the 〈 2 μm fraction is made up of smectite, illite, kaolinite and chlorite. Aragonite and calcite are mainly derived from benthic accumulations, whereas feldspars (mainly plagioclase) and smectite reflect magmaticvolcanic provenance and the distribution of 1 nm-micas and chlorite correlate with nearby metamorphic sources onland. Nevertheless, grain size and mineral distribution generally indicate a combination of effects of wind and wave climate, longshore and offshore cyclonic currents, changing sea-level stands and nearby source rock and morphological conditions. It is also suggested that at least part of clay minerals could be derived from the northwesterly Danube River input. 相似文献
933.
Zircon textures, chemistry and microstructures have been characterized in situ within Carboniferous sandstones from the Midland Valley of Scotland using back‐scattered electron and cathodoluminescence images, electron backscatter diffraction techniques and chemical analyses. The study of polished thin sections reveals a variety of zircon types including unmodified detrital zircon, zircon outgrowths and different forms of modified zircon that formed in low‐temperature conditions within the sedimentary rocks. These rocks have only experienced temperatures of <100 °C during burial; however, altered zircon is abundant and characterized by a low mean atomic number, with relatively high contents of non‐formula elements and a nano‐crystalline or microcrystalline structure. It forms by replacement of detrital zircon that subsequently became metamict. Two types of replacement mechanisms are effective in sedimentary environments and involve either dissolution–reprecipitation or solid‐state reaction, but both require fluid access to the radiation‐damaged areas. The former process appears to become the dominant replacement mechanism as temperature increases and produces highly porous, inclusion‐rich zircon. Metamict zircon is extremely reactive in near‐surface conditions and the production of low‐temperature zircon is sensitive to both parent zircon characteristics and environmental conditions. As such, the alteration of zircon has the potential to yield unique information on the diagenetic history of sedimentary rocks. Low‐temperature zircon would be unlikely to survive sedimentary transport or the rock crushing procedures that characterize many investigations of detrital zircon populations and consequently may generate severe biases in studies of this type. 相似文献
934.
A. S. Montin 《Moscow University Geology Bulletin》2009,64(4):262-264
This paper discusses geological features of the Lukkulajsvaara platinum-bearing intrusion. Particular attention is paid to platinum-bearing layers, namely petrographic features of ore-bearing rocks, their structure, texture, and the mineralogical composition of the ore. This allowed the revelation of some features of platinum ore formation, in which postcumulus liquids enriched in fluids played the main role. 相似文献
935.
Ajay Kumar S. N. S. Birua Dheeraj Pande A. R. Nath P. V. Ramesh Babu S. A. Pandit 《Journal of the Geological Society of India》2009,73(4):537-542
Several radioactive quartz-pebble conglomerate (QPC) occurrences at the western margin of Archaean Bonai granite and overlying
Iron Ore Group (IOG) rocks have recently been located over a total strike length of 8–10 km intermittently in a NE-SW to E-W
trend with steep dips due north-west to north in parts of Sundargarh district of Orissa. The QPC samples have analysed up
to 0.039% U3O8 and 0.035% ThO2 with high concentration of Y (74 to 518 ppm), La(<100 to 880 ppm), Cr ( 126 to 633 ppm), Zr (137 to 1250 ppm) and Pb (31
to 581 ppm). Cellulose Nitrate (CN) film studies of few QPC samples indicated adsorbed uranium over goethite and infiltrated
ferruginous material (limonite), secondary uranium as encrustation and fracture filling and discrete sub-rounded grains of
monazite, zircon, allanite and rare xenotime in the matrix of QPC as radioactive phases. Higher content of Th over U, elevated
concentration of Y and La in QPC eliminates the possibility of its low temperature product by epigenetic processes. Poor correlation
of U with elements like Pb, Y, Zr, La and Cr can be explained due to surficial leaching of uranium from QPC after its deposition
as reflected by adsorbed U over iron-oxides and low U/Th ratio in QPC in the area. 相似文献
936.
Shuichi Hasegawa Ranjan Kumar Dahal Minoru Yamanaka Netra Prakash Bhandary Ryuichi Yatabe Hideki Inagaki 《Environmental Geology》2009,57(6):1423-1434
Geologically and tectonically active Himalayan Range is characterized by highly elevated mountains and deep river valleys.
Because of steep mountain slopes, and dynamic geological conditions, large-scale landslides are very common in Lesser and
Higher Himalayan zones of Nepal Himalaya. Slopes along the major highways of central Nepal namely Prithvi Highway, Narayangadh-Mugling
Road and Tribhuvan Highway are considered in this study of large-scale landslides. Geologically, the highways in consideration
pass through crushed and jointed Kathmandu Nappe affected by numerous faults and folds. The relict large-scale landslides
have been contributing to debris flows and slides along the highways. Most of the slope failures are mainly bechanced in geological
formations consisting phyllite, schist and gneiss. Laboratory test on the soil samples collected from the failure zones and
field investigation suggested significant hydrothermal alteration in the area. The substantial hydrothermal alteration in
the Lesser Himalaya during advancement of the Main Central Thrust (MCT) and thereby clay mineralization in sliding zones of
large-scale landslide are the main causes of large-scale landslides in the highways of central Nepal. This research also suggests
that large-scale landslides are the major cause of slope failure during monsoon in the Lesser Himalaya of Nepal. Similarly,
hydrothermal alteration is also significant in failure zone of the large-scale landslides. For the sustainable road maintenance
in Nepal, it is of utmost importance to study the nature of sliding zones of large-scale landslides along the highways and
their role to cause debris flows and slides during monsoon period. 相似文献
937.
据矿床分布特点,将武平地区与晚侏罗世侵入岩有关的的钼矿(化)分为石英脉型钼多金属矿和云英岩型钼钨矿2种类型,并据成矿地质特征,结合地球化学异常,分析其控矿因素,提出找矿标志及找矿方向。 相似文献
938.
苏北盆地粘土矿物转化模式与古地温 总被引:16,自引:0,他引:16
以苏北盆地为例,系统研究了火成岩发育区粘土矿物组合特征及其控制因素;建立了粘土矿物转化模式;根据粘土矿物成岩演化特点,进行古地温分析。研究表明,苏北地区粘土矿物的分布主要受埋藏成岩作用、岩浆侵入、母质来源三种因素的影响,发育四种类型的粘土矿物组合和三种粘土矿物转化模式;火山碎屑岩母岩区和基性岩浆侵入区具有特殊的粘土矿物组合和成岩演化模式,前者以富含蒙皂石矿物为特点;后者出现高岭石与伊/蒙有序间层矿物共生组合,并具有不连续的演化序列;苏北盆地短有序I/S矿物出现于镜质组反射率 0.5 %~ 0.5 5 %的深度,伊/蒙间层矿物转变成伊利石在镜质组反射率 0.75 %~ 0.8%,可以用于热成熟度和古地温的估算;而蒙皂石消失的界面则不具有指标意义 相似文献
939.
正20140697Gao Wenyuan(College of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China);Huang Fei The Influence of Different Iron-Sulfur Ratios on Pyrite Formation under Thermal Sulfurization Condition(Earth Science Frontiers,ISSN1005-2321,CN11-3370/P,20(3),2013,p.131-137,6illus.,3tables,19refs.)Key words:pyrite,crystallization 相似文献
940.