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青藏高原影响亚洲夏季气候研究的最新进展 总被引:40,自引:6,他引:40
文中回顾了近 10a来吴国雄等在青藏高原影响亚洲夏季气候研究方面的最新进展。通过分析东西风交界面的演变证明 ,由于青藏高原的春季加热 ,亚洲季风区对流层低层冬季盛行偏东风转变为夏季偏西南风最早发生在孟加拉湾东部 ,与其相伴随的激烈对流降水出现在其东面。因此孟加拉湾东部至中印半岛西部是亚洲季风最早爆发的地区。同时也指出盛夏伊朗高原和青藏高原加热所激发的同相环流嵌套在欧亚大陆尺度的热力环流中 ,从而加强了东亚的夏季风 ,加剧了中西亚的干旱 ;并通过其所激发的波动对夏季东亚的气候格局产生重要影响。文中还比较了夏季南亚高压的伊朗模态和青藏模态性质的异同及其对亚洲夏季降水异常分布的不同影响。 相似文献
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The Zhangjiakou–Penglai seismotectonic zone (ZPSZ) lies in the northern part of North China and extends along the Zhangjiakou–Beijing–Tianjin–Bohai Bay–Penglai–Yellow Sea. It is about 900 km long and some 250 km wide in a northwest direction. The great Sanhe-Pinggu (MS=8.0) earthquake occurred on September 1679 and the Tangshan (MS=7.8) earthquake on July 1976 caused serious economic and life losses. According to some differences in crust structure and regional tectonic stress field, the ZPSZ is divided into western and eastern segment by the 117°E line for study on long-term seismic hazard analysis. An analysis of Gutenberg–Richter's empirical relation of earthquake-frequency and time process of historic and recent earthquakes along the eastern and western segments shows that the earthquake activity obeys a Poisson process, and these calculations indicate that the earthquake occurrence probability of MS=6.0–6.9 is 0.77–0.83 in the eastern segment and the earthquake occurrence probability of MS=7.0–7.9 is 0.78–0.80 in the western segment of the ZPSZ during a period from 2005 to 2015. 相似文献
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Genesis of Kanggur Gold Deposit in Eastern Tianshan Orogenic Belt, NW China: Fluid Inclusion and Oxygen and Hydrogen Isotope Constraints 总被引:3,自引:0,他引:3
Abstract. Primary fluid inclusions in quartz and carbonates from the Kanggur gold deposit are dominated by aqueous inclusions, with subsidiary CO2 -H2 O inclusions that have a constant range in CO2 content (10–20 vol %). Microthermometric results indicate that total homogenization temperatures have a wide but similar range for both aqueous inclusions (120 to 310C) and CO2 -H2 O inclusions (140 to 340C). Estimates of fluid salinity for CO2 -H2 O inclusions are quite restricted (5.9∼10.3 equiv. wt% NaCl), whereas aqueous inclusions show much wider salinity ranging from 2.2 to 15.6 equivalent wt %NaCl.
The 6D values of fluid inclusions in carbonates vary from -45 to -61 %, in well accord with the published δD values of fluid inclusions in quartz (-46 to -66 %). Most of the δ18 O and δD values of the ore-forming fluids can be achieved by exchanged meteoric water after isotopic equilibration with wall rock by fluid/rock interaction at a low water/rock ratio. However, the exchanged meteoric water alone cannot explain the full range of δ18 O and δD values, magmatic and/or meta-morphic water should also be involved. The wide salinity in aqueous inclusions may also result from mixing of meteoric water and magmatic and/or metamorphic water. 相似文献
The 6D values of fluid inclusions in carbonates vary from -45 to -61 %, in well accord with the published δD values of fluid inclusions in quartz (-46 to -66 %). Most of the δ
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Xiaofeng Li Chunzeng Wang Jingwen Mao Renmin Hua Yarning Liu Qinghong Xu 《Resource Geology》2005,55(4):397-404
Abstract. The Yinshan polymetallic deposit is a hydrothermal vein-type deposit closely related to Late Jurassic felsic-inter-mediate volcanic-subvolcanic activity in Jiangxi Province, South China. Illite is a major alteration mineral observed in the deposit. Our study shows that the Kübler index of the illite has a close relation to ore-forming fluids of different stages of hydrothermal alteration and mineralization. The early Pb-Zn-Ag mineralization dated at 130–136 Ma is characterized by relatively low water/rock ratios and diffusive fluid movement within phyllite, whereas the later Cu-Au-S mineralization at 122 -125 Ma was accompanied by higher water/rock ratios and localized fluid flow through fractures and channels. Illite formed in the early Pb-Zn-Ag mineralization stage contains swelling layers while the illite formed in the later Cu-Au-S mineralization stage has no swelling layers but was associated with intensive chloritization. The last stage of mineralization (at 104 Ma) was minor and did not produce significant amounts of illite. 相似文献
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体绘制技术在地学3D GIS 可视化中的应用研究 总被引:1,自引:0,他引:1
体绘制技术是目前科学计算可视化研究的一个重要组成部分,对地质体内部属性分布的可视化有重要意义。该文针对地学研究中几何建模和属性建模同样重要的特点,基于一种矢栅一体化的混合数据模型,对地质体表面采用三角面片描述几何形状,对地质体内部采用基于八叉树的自适应网格剖分技术描述内部属性特征。对网格剖分后的体数据,采用体元投射的体绘制技术进行地质体内部属性可视化,显示出很好的效果,具有实际应用意义。 相似文献
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Salinity is a vital factor that regulates leaf photosynthesis and growth of mangroves, and it frequently undergoes large seasonal and daily fluctuations creating a range of environments – oligohaline to hyperhaline. Here, we examined the hypotheses that mangroves benefit opportunistically from low salinity resulting from daily fluctuations and as such, mangroves under daily fluctuating salinity (FS) grow better than those under constant salinity (CS) conditions. We compared growth, salt accumulation, gas exchange, and chlorophyll fluorescence of leaves of mangrove Bruguiera gymnorhiza seedlings growing in freshwater (FW), CS (15 practical salinity units, PSU), and daily FS (0–30 PSU, average of 4.8 PSU) conditions. The traits of FS-treated leaves were measured in seedlings under 15 PSU. FS-treated seedlings had greater leaf biomass than those in other treatment groups. Moreover, leaf photosynthetic rate, capacity to regulate photoelectron uptake/transfer, and leaf succulence were significantly higher in FS than in CS treatment. However, leaf water-use efficiency showed the opposite trend. In addition to higher concentrations of Na+ and Cl−, FS-treated leaves accumulated more Ca2+ and K+. We concluded that daily FS can enhance water absorption, photosynthesis, and growth of leaves, as well as alter plant biomass allocation patterns, thereby positively affecting B. gymnorhiza. Mangroves that experience daily FS may increase their adaptability by reducing salt build-up and water deficits when their roots are temporally subjected to low salinity or FW and by absorbing sufficient amounts of Na+ and Cl− for osmotic adjustment when their roots are subsequently exposed to saline water. 相似文献