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961.
962.
贵州瓮安生物群和磷矿形成的沉积地球化学研究 总被引:12,自引:0,他引:12
运用沉积学和元素地球化学的理论和方法,通过对瓮福磷矿陡山沱组地层古地理背景与沉积环境分析,进一步揭示沉积记录中热水作用的客观存在性。研究认为,上震旦统陡山沱组“瓮安生物群”繁盛及磷块岩富集与海底热水喷流活动存在联系,热水活动在海洋生物的繁盛和海洋磷的运移过程中可能扮演了一个极其重要的角色,在缺氧带和亚氧化带的大量细菌对磷的分解和有影响力的铁—硫酸盐的循环作用下,富集的磷在海底上升洋流作用下,运移到氧化还原界面上富集成矿。 相似文献
963.
再论内蒙古大井锡铜多金属矿床成因 总被引:7,自引:0,他引:7
通过笔者1985年以来对该矿床的研究表明,该矿床的成矿过程受“双模式成因机制”控制,即由于韧性剪切糜棱岩化作用促使二叠系上统林西组中的成矿元素发生活化、迁移、富集,形成初始矿源层,与此同时或稍后,燕山期(K-Ar法,155.3 ̄177.2Ma)火山一次火山热液活动从深部所携成矿物质迭加在初始矿源层之上,形成矿床。 相似文献
964.
965.
鄂尔多斯盆地煤成烃潜力与成气热模拟实验 总被引:3,自引:1,他引:3
鄂尔多斯盆地煤的Rock Eval分析结果表明,在肥煤—焦煤阶段,S1+S2达最大值,随后生烃潜力减弱。煤的Py GC分析及热模拟成气实验结果证实煤成气具有3个生气高峰,分别相应于Ro,m05%~07%、10%~14%及25%,表明煤成气具多阶段性的特点。这一规律性的认识有助于煤成气的勘探和开发。同时,随煤级增高,煤成烃特征亦发生有规律的变化:异构烃减少,正构烃增加;类异戊二烯烷烃分布亦存在多变性或多阶段的演化特点;苯系化合物具波动性变化特征。 相似文献
966.
Teyruyoshi Imaoka Kazuo Nakashima Testumaru Itaya Toshinori Okada 《Resource Geology》2001,51(1):55-62
Abstract: Crystallinity, chemical compositions and K-Ar ages of sericites in highly-sericitized granites and associated fissure-filling veins were examined to delineate the timing and duration of the hydrothermal activity in the Oligocene Hamada cauldron in the San-in district, SW Japan. Sericite separates (>2 μm) from the highly-sericitized granites consist mainly of 2M1 polytype having high crystallinity and low Kübler indices of 0.22–0.35, while those in the fissure-filling veins have lower 2M1 /1Md ratios and crystallinity, and high Kübler indices of 0.29–0.35. This suggests that the sericites in highlysericitized granites were formed at a higher temperature than the vein sericites.
Sericites from the highly-sericitized granites of the Kumogi pluton give K-Ar ages of 30.0±0.7, 30.4±0.7, 30.6±0.7, 30.6±0.7, 32.1±0.7, 32.3±0.7 and 33.0±0.7 Ma (1), while those of the central plutons, 33.8±0.7 and 33.8±0.7 Ma. Sericites in the fissure-filling veins of the Kumogi granite give K-Ar ages of 31.0±0.7, 31.5±0.7, 31.6±0.7, 31.7±0.7 and 32.3±0.7 Ma. Biotite separates from the fresh Kumogi granite give K-Ar ages of 31.7±0.8, 32.0±0.8, 32.7±0.7 and 33.5±0.7 Ma. The K-Ar age data revealed that the hydrothermal alteration began at about 33 Ma and ended by about 30 Ma and that the period of sericite alteration was nearly synchronous with the cooling of the granite intrusions in the Hamada cauldron.
Despite intense hydrothermal alteration, the Oligocene granitoids have not accompanied with any economic base metal mineralization. The bulk chemical analyses of sericite separates in the veins indicate that the post-magmatic fluids were originally barren in heavy metals. 相似文献
Sericites from the highly-sericitized granites of the Kumogi pluton give K-Ar ages of 30.0±0.7, 30.4±0.7, 30.6±0.7, 30.6±0.7, 32.1±0.7, 32.3±0.7 and 33.0±0.7 Ma (1), while those of the central plutons, 33.8±0.7 and 33.8±0.7 Ma. Sericites in the fissure-filling veins of the Kumogi granite give K-Ar ages of 31.0±0.7, 31.5±0.7, 31.6±0.7, 31.7±0.7 and 32.3±0.7 Ma. Biotite separates from the fresh Kumogi granite give K-Ar ages of 31.7±0.8, 32.0±0.8, 32.7±0.7 and 33.5±0.7 Ma. The K-Ar age data revealed that the hydrothermal alteration began at about 33 Ma and ended by about 30 Ma and that the period of sericite alteration was nearly synchronous with the cooling of the granite intrusions in the Hamada cauldron.
Despite intense hydrothermal alteration, the Oligocene granitoids have not accompanied with any economic base metal mineralization. The bulk chemical analyses of sericite separates in the veins indicate that the post-magmatic fluids were originally barren in heavy metals. 相似文献
967.
从系统学和协同学角度研究分析了秦岭造山带泥盆纪三级构造热水沉积成矿盆地的主控因素。认为三级构造热水沉积成矿盆地是受诸多因素控制的一个构造—热水成岩成矿系统 (一种非线性、自组织系统 )。秦岭深部岩石圈地幔近南北向收缩与佛坪大陆热点构造 ( hotspot)的耦合 ,引发陆壳浅部发生近东西向伸展 ,触发热水 (能 )从深部向陆壳浅部大规模运移。近东西向高序次同生断裂控制一级沉积盆地的形成与演化。不同级次的同生断裂是控盆—成盆的主控因素 ,低序次 NE向、NW向和 SN向同生断裂是秦岭造山带泥盆纪三级构造热水沉积成矿盆地的主控因素 ,也是热水喷流进入盆地的构造通道。三级构造沉积盆地为热水成岩成矿系统发生大规模聚集成矿提供了构造空间 相似文献
968.
Benoît Villemant Georges Boudon J.-C. Komorowski 《Earth and Planetary Science Letters》1996,140(1-4):259-267
Volcanic rocks from subduction zones are widely believed to originate by partial melting of mantle lherzolite modified by the addition of a fluid or melt extracted from the down-going slab. U-series disequilibrium in such magmas is commonly attributed to this particular melting process. A detailed study of U-series isotopes in the 650 y. B.P. eruptive sequence of Mt. Pelée (Martinique) shows that plinian products are in radioactive equilibrium, whereas dome-forming products of the same eruption are characterized by 238U-230Th disequilibrium. The same features apply to other plinian and dome-forming products of this volcano and systematically correspond to different eruptive styles. We attribute these characteristics to variable superficial interaction of magmas with the hydrothermal system during the final stages of eruption rather than to deep magma genesis processes. This conclusion might be generally applicable to arc magmas. 相似文献
969.
皖南地区上震旦统蓝田组,是银铅锌等多金属矿床的重要赋矿层位,区域地质,矿床地质和地球化学特征研究表明,银铅锌等多金属矿床是由于热水沉积作用而形成,热水沉积作用受断裂控制明显,主要呈带状沿着祁门-三阳坑一万家桥深断裂NE方向展布,热水学沉积形成了银铅锌等多金属矿床,铁锰矿床以及蓝田组底部数千平方千米含锰碳酸盐岩,这一认识不仅为皖南地区矿床的成因给予了新的解释,也为今后该区矿产资源的勘察工作提供了新的思路。 相似文献
970.
K. Yang P. R. L. Browne J. F. Huntington J. L. Walshe 《Journal of Volcanology and Geothermal Research》2001,106(1-2)
Hydrothermal clay minerals present in the Broadlands–Ohaaki geothermal field were characterised by field portable short-wave infrared spectroscopy. Three major alteration zones, an upper smectite, a middle illite and a lower illite–chlorite, are spectrally separable. The zoning pattern is generally consistent with the thermal structure of the geothermal field, although occasionally zone boundaries cut present-day isotherms. The data indicate that temperature is the major control on clay zoning and permeability plays a subordinate role.Both beidellite and montmorillonite are common in the upper, low-temperature smectite zone. Kaolinite, mainly of low crystallinity, marks the margin of the field where cool acidic ground waters inflow. In the middle alteration zone, illite, dominantly K-rich, shows a narrow compositional variability. Some highly permeable zones are characterised by illite with low octahedral Al contents. Ammonium-bearing illite and buddingtonite are present locally in permeable horizons within the illite zone, where temperatures are above 200°C. Chlorite is most abundant in the lower alteration zone (temperature >250°C), although it also occurs unevenly in the upper and middle alteration zones. Chlorite varies from Mg- to Fe-rich varieties (but mostly with Mg# values <0.5), but no compositional trends with respect to depth are spectrally detectable. 相似文献