全文获取类型
收费全文 | 10535篇 |
免费 | 2469篇 |
国内免费 | 5951篇 |
专业分类
测绘学 | 33篇 |
地球物理 | 246篇 |
地质学 | 17535篇 |
海洋学 | 115篇 |
综合类 | 914篇 |
自然地理 | 112篇 |
出版年
2024年 | 113篇 |
2023年 | 365篇 |
2022年 | 467篇 |
2021年 | 510篇 |
2020年 | 490篇 |
2019年 | 553篇 |
2018年 | 500篇 |
2017年 | 652篇 |
2016年 | 786篇 |
2015年 | 756篇 |
2014年 | 1011篇 |
2013年 | 787篇 |
2012年 | 1041篇 |
2011年 | 938篇 |
2010年 | 872篇 |
2009年 | 720篇 |
2008年 | 664篇 |
2007年 | 729篇 |
2006年 | 668篇 |
2005年 | 595篇 |
2004年 | 594篇 |
2003年 | 526篇 |
2002年 | 495篇 |
2001年 | 540篇 |
2000年 | 510篇 |
1999年 | 474篇 |
1998年 | 465篇 |
1997年 | 443篇 |
1996年 | 399篇 |
1995年 | 315篇 |
1994年 | 250篇 |
1993年 | 184篇 |
1992年 | 165篇 |
1991年 | 126篇 |
1990年 | 74篇 |
1989年 | 69篇 |
1988年 | 47篇 |
1987年 | 28篇 |
1986年 | 18篇 |
1985年 | 9篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Abstract. Lermontovskoe tungsten skarn deposit in central Sikhote-Alin is concluded to have formed at 132 Ma in the Early Cretaceous, based on K-Ar age data for muscovite concentrates from high-grade scheelite ore and greisenized granite. Late Paleozoic limestone in Jurassic - early Early Cretaceous accretionary complexes was replaced during hydrothermal activity related to the Lermontovskoe granodiorite stock of reduced type. The ores, characterized by Mo-poor scheelite and Fe3+- poor mineral assemblages, indicate that this deposit is a reduced-type tungsten skarn (Sato, 1980, 1982), in accordance with the reduced nature of the granodiorite stock.
The Lermontovskoe deposit, the oldest mineralization so far known in the Sikhote-Alin orogen, formed in the initial stage of Early Cretaceous felsic magmatism. The magmatism began shortly after the accretionary tectonics ceased, suggesting an abrupt change of subduction system. Style of the Early Cretaceous magmatism and mineralization is significantly different between central Sikhote-Alin and Northeast Japan; reduced-type and oxidized-type, respectively. The different styles may reflect different tectonic environments; compressional and extensional, respectively. These two areas, which were closer together before the opening of the Japan Sea in the Miocene, may have been juxtaposed under a transpressional tectonic regime after the magmatism. 相似文献
The Lermontovskoe deposit, the oldest mineralization so far known in the Sikhote-Alin orogen, formed in the initial stage of Early Cretaceous felsic magmatism. The magmatism began shortly after the accretionary tectonics ceased, suggesting an abrupt change of subduction system. Style of the Early Cretaceous magmatism and mineralization is significantly different between central Sikhote-Alin and Northeast Japan; reduced-type and oxidized-type, respectively. The different styles may reflect different tectonic environments; compressional and extensional, respectively. These two areas, which were closer together before the opening of the Japan Sea in the Miocene, may have been juxtaposed under a transpressional tectonic regime after the magmatism. 相似文献
82.
The Ore-forming Fluid of the Gold Deposits of Muru Gold Belt in Eastern Shandong, China - a Case Study of Denggezhuang Gold Deposit 总被引:1,自引:0,他引:1
Qingdong Zeng Jianming Liu Hongtao Liu Ping Shen Lianchang Zhang 《Resource Geology》2006,56(4):375-384
Abstract. Denggezhuang gold deposit is an epithermal gold‐quartz vein deposit in northern Muru gold belt, eastern Shandong, China. The deposit occurs in the NNE‐striking faults within the Mesozoic granite. The deposit consists of four major veins with a general NNE‐strike. Based on crosscutting relationships and mineral parageneses, the veins appear to have been formed during the same mineralization epochs, and are further divided into three stages: (1) massive barren quartz veins; (2) quartz‐sulfides veins; (3) late, pure quartz or calcite veinlets. Most gold mineralization is associated with the second stage. The early stage is characterized by quartz, and small amounts of ore minerals (pyrite), the second stage is characterized by large amounts of ore minerals. Fluid inclusions in vein quartz contain C‐H‐O fluids of variable compositions. Three main types of fluid inclusions are recognized at room temperature: type I, two‐phase, aqueous vapor and an aqueous liquid phase (L+V); type II, aqueous‐carbonic inclusions, a CC2‐liquid with/without vapor and aqueous liquid (LCO2+VCC2+Laq.); type III, mono‐phase aqueous liquid (Laq.). Data from fluid inclusion distribution, microthermometry, and gas analysis indicate that fluids associated with Au mineralized quartz veins (stage 2) have moderate salinity ranging from 1.91 to 16.43 wt% NaCl equivalent (modeled salinity around 8–10 wt% NaCl equiv.). These veins formatted at temperatures from 80d? to 280d?C. Fluids associated with barren quartz veins (stage 3) have a low salinity of about 1.91 to 2.57 wt% NaCl equivalent and lower temperature. There is evidence of fluid immiscibility and boiling in ore‐forming stages. Stable isotope analyses of quartz indicate that the veins were deposited by waters with δO and δD values ranging from those of magmatic water to typical meteoric water. The gold metallogenesis of Muru gold belt has no relationship with the granite, and formed during the late stage of the crust thinning of North China. 相似文献
83.
Jens Gutzmer 《Mineralium Deposita》2006,40(6-7):664-685
The Pering deposit on the Ghaap Plateau, Northwestern Province, South Africa, was the largest of several Zn–Pb occurrences hosted by Neoarchean platform dolostones of the Transvaal Supergroup. With a Paleoproterozoic mineralization age, these occurrences are widely regarded as the oldest representatives of Mississippi Valley-type Pb–Zn deposits. Hosting an initial resource of 18 Mt at an average grade of 3.6 wt% Zn and 0.6 wt% Pb, the Pering deposit was mined from 1984 until its final closure at the end of November 2002. In this study, available geological and grade distribution maps were evaluated and complemented by the examination of mining-related outcrops, drill core, and a large set of ore and host rock samples. Four different styles of brecciation can be distinguished at the Pering deposit: (1) pyritic rock matrix breccia; (2) chemical wear breccia; (3) mosaic breccia; and (4) crackle breccia. Geological and mineral paragenetic observations on these different breccia types suggest that the formation of the Pering deposit commenced with an initial stage of hydrothermal karstification. Large volumes of pyritic rock matrix breccia formed by wall rock collapsing into the open space attributed to carbonate dissolution. This stage of hydrothermal karstification acted as ground preparation for the subsequent mineralization event. By the upward advance of the hydrothermal karstification process, fluid reservoirs in the previously undisturbed dolostone host rock succession were tapped, ultimately leading to fluid mixing. Hydrothermal sulphides are the most abundant where fluid mixing was most effective, i.e. along the outer and upper margins of the breccia bodies, and in stratabound zones along permeable host rock units. Chemical wear brecciation and formation of large volumes of fine-grained replacive sphalerite mineralization mark the early stage of hydrothermal Zn–Pb mineralization associated with this fluid mixing. The fine-grained stage of sulphide mineralization was succeeded by very coarse-grained open-space-infill mineralization. The latter is very uniform across the entire deposit and typically cements mosaic and crackle breccia, but also fills remaining open space within chemical wear brecciated portions of the deposit. 相似文献
84.
通过对邯郸市某车间地基的勘察.分析和探讨了新近沉积粉细砂地层的勘察手段、其物理力学性质,及其利用载荷试验确定承载力的标准取得了较为满意的结果,提出的一些分析方法,对新近沉积的粉细砂地层的勘察具有一定的借鉴作用。 相似文献
85.
Gehad M. Saleh 《中国地球化学学报》2006,25(4):307-317
1 Introduction The association of massive Fe-Ni-Cu sulfides andchromite is a very unusual feature of podiformchromitites occurring in mantle tectonites of ophioliticcomplexes. It has only been described in theSoutheastern Desert, Egypt, where sulfides a… 相似文献
86.
1 Introduction The Ordos Basin is the second largest sedimentary basin in China. During the last 10 years, a great progress has been achieved in the aspects of tectonic evolution, dynamics process, inner and outer geological processes during Mesozoic-Cen… 相似文献
87.
1 Introduction Alunite [KAl3(SO4)2(OH)6] is a very important non-ferrous metal resource, so many countries throughout the world have made great investments in research on the mechanism of its formation, its geological characteristics and applications. O… 相似文献
88.
本文首次对藏南地区金和锑矿床(点)地质特征、成因类型和空间分布特点进行了总结,对金和锑成矿作用与中新生代构造一岩浆活动的关系进行了论证,对区域地壳演化过程中金和锑成矿动力学机制进行了讨论。该区的金和锑矿床(点)可按容矿围岩划分为:①变质岩为主要容矿围岩矿床(点),包括金和金一锑矿床(点);②沉积岩为主要容矿围岩矿床(点),包括金、锑、金一锑和锑多金属矿床(点);③火山岩为主要容矿围岩矿床(点),以金一银矿床为代表。根据金和锑矿床(点)空间分布特点和地质特点,将本区划分为4个矿化集中区:拉昂错一马攸木一帕羊金矿化集中区(A),然勒金和锑矿化集中区(B),洛扎一措美锑矿化集中区(C)和邛多江金一锑矿化集中区(D)。各矿化集中区内大多数金和锑矿床(点)与燕山晚期~喜马拉雅早期富碱火成岩具密切时空分布关系,它们是古板块对接碰撞期和碰撞期后大规模构造一岩浆活动的产物。近东西向挤压性和南北向张性断裂交汇部位以及富碱火成岩发育区是寻找金和锑矿床(点)的有利场所。 相似文献
89.
90.
土屋铜矿上方覆盖层元素分布规律研究 总被引:1,自引:0,他引:1
通过对土屋铜矿上方覆盖层不同层位样品进行分析发现,成矿元素Cu在覆盖层底部靠近基岩的原地风化残积层和地表弱胶结层中富集,而在地衰弱胶结层中又倾向于向两“极”富集,即在最粗粒级和最细粒级含量较高.考虑到采样效率和成本等综合因素,在区域调查中,以采集弱胶结层(5~40cm)、细粒级样品(-160目)为最佳采样介质. 相似文献