全文获取类型
收费全文 | 1116篇 |
免费 | 182篇 |
国内免费 | 593篇 |
专业分类
测绘学 | 1篇 |
地球物理 | 105篇 |
地质学 | 1676篇 |
海洋学 | 47篇 |
综合类 | 49篇 |
自然地理 | 13篇 |
出版年
2024年 | 6篇 |
2023年 | 13篇 |
2022年 | 34篇 |
2021年 | 33篇 |
2020年 | 46篇 |
2019年 | 44篇 |
2018年 | 50篇 |
2017年 | 62篇 |
2016年 | 60篇 |
2015年 | 59篇 |
2014年 | 61篇 |
2013年 | 91篇 |
2012年 | 108篇 |
2011年 | 76篇 |
2010年 | 73篇 |
2009年 | 96篇 |
2008年 | 97篇 |
2007年 | 91篇 |
2006年 | 80篇 |
2005年 | 99篇 |
2004年 | 78篇 |
2003年 | 85篇 |
2002年 | 52篇 |
2001年 | 48篇 |
2000年 | 50篇 |
1999年 | 63篇 |
1998年 | 40篇 |
1997年 | 36篇 |
1996年 | 35篇 |
1995年 | 29篇 |
1994年 | 29篇 |
1993年 | 25篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 2篇 |
排序方式: 共有1891条查询结果,搜索用时 69 毫秒
961.
Hanning Wu Rixiang Zhu Vincent Courtillot Lixin Bai Jianxiao Xing Yongxin Zhao Gelian Yang 《中国科学D辑(英文版)》1999,42(2):182-194
The paleomagnetic reconnaissance study of the Paleozoic and Mesozoic sedimentary rocks from the Yangtze Block (YZB) was made
to conduct the Apparent Polar Wander Path (APWP) of the YZB during the Phanerozoic. A total of 825 samples from 84 sites were
collected from a continuous section along the Xiangxi River valley in Xingshan and Zigui counties in Hubei Province, northern
margin of the YZB. Stepwise thermal/alternating demagnetization isolated well defined characteristic magnetization (ChRM)
at a higher temperature in most of the samples, and relatively thermal stability and high coercivity were revealed from these
samples. All the ChRMs can pass the fold and/or reversal tests, suggesting that they are probably primary. Therefore, new
pole positions are presented for the YZB.
Project supported by the National Natural Science Foundation of China (Grant No. 49334050). 相似文献
962.
The Higo metamorphic terrane situated in west-central Kyushu island, southwest Japan, is composed of greenschist- to granulite-facies metamorphic rocks. The southern part of the metamorphic terrane consists mainly of garnet–biotite gneiss and garnet–cordierite–biotite gneiss, and orthopyroxene or cordierite-bearing S-type tonalite with subordinate amounts of hornblende gabbro. Rb–Sr, Sm–Nd and K–Ar isotopic ages for these rocks have been determined here. The garnet–biotite gneiss gives an Sm–Nd age of 227.1 ± 4.9 Ma and a Rb–Sr age of 101.0 ± 1.0 Ma. The hornblende gabbro has an Sm–Nd age of 257.9 ± 2.5 Ma and a K–Ar age of 103.4 ± 1.1 Ma. These age differences of the same samples are due to the difference in the closure temperature for each system and minerals. The garnet-cordierite–biotite gneiss contains coarse-grained garnet with a zonal structure conspicuously distinguished in color difference (core: dark red; rim: pink). Sm–Nd internal isochrons of the garnet core and the rim give ages of 278.8 ± 4.9 Ma (initial 143 Nd/144 Nd ratio = 0.512311 ± 0.000005) and 226.1 ± 28.4 Ma (0.512277 ± 0.000038), respectively. These ages are close to formation of the garnet core and the rim. It has been previously suggested that the Higo metamorphic terrane belongs to the Ryoke metamorphic belt. But Sr and Nd isotopic features of the rocks from the former are different from those of the Ryoke metamorphic rocks, and are similar to those of the granulite xenoliths contained in the Ryoke younger granite. 相似文献
963.
Jurassic and Early Cretaceous Radiolaria of the Lower Amurian Terrane: Khabarovsk region, far east of Russia 总被引:3,自引:0,他引:3
New data on biostratigraphy, sedimentology and tectonics of the Russian Far Eastern region (Lower Amurian terrane) are presented. This study shows that sedimentary sequence of the terrane consists of interbedded Radiolaria-bearing siliceous and volcaniclastic sediments spanning an interval of over 90 million years. It is shown that accumulation of radiolarian deposits on an oceanic plate was associated with alkaline (intraplate) volcanism in the Jurassic, while the plate was drifting, and with some arc volcanism during the Early Cretaceous. The younger siliceous rocks contain volcaniclastic material and indicate that the studied sequence approached the trench in the Early Cretaceous (Hauterivian-Barremian) and became accreted in the late Albian–early Cenomanian. We describe and illustrate radiolarian species extracted from 21 samples. A taxonomic list of 194 taxa and nine plates of Jurassic–Early Cretaceous Radiolaria are presented. 相似文献
964.
965.
江苏赣榆城头地区中生代侵入岩岩石谱系单位划分 总被引:2,自引:2,他引:0
城头地区中生代侵入体经地面调查和对比分析,初步建立了夹山、朱苍2序列共7个单元,其矿物成分、结构构造、岩石化学、地球化学特征有一定的演化规律,根据同位素年龄及区域地质资料,确定夹山序列为早白垩世侵入岩,朱苍序列为晚侏罗世或更早的侵入岩,两个序列皆属Ⅰ型花岗岩,岩浆来源初步认为是上地幔与下部地壳经同熔作用的产物,侵位机制为受北东向构造控制的被动式侵位。 相似文献
966.
太行山南段中生代侵入体微量元素地球化学及岩浆源区性质探讨 总被引:3,自引:0,他引:3
本文对在行山南中生代侵入岩体微量元素地球化学进行了系统研究,成果表明各类侵入岩的稀土配分模式均呈轻稀土富重稀土与亏损,且没有铕异常,认为这是由于岩石中副矿物中的负铕异常与主要矿物长石类矿物中高的正铕异常低消的结果,本文还探讨了岩浆源区的特点,认为为本区岩石多具幔壳混合来源(MC型)部分来自幔源(MC型)。 相似文献
967.
变质地体是国内外金矿集中分布区。综述了已建立的成矿模式,包括药岗绿岩带成矿模式、多阶段多成因模式、地壳连续成矿模式、中酸性岩浆和基性、超基性、岩浆深源混合成矿模式等。同时联系我国实际,指出了我国变质地体中与花岗-绿岩带有关的金矿床的若干特点和进一步找矿方向。 相似文献
968.
969.
在北苏鲁超高压变质带(UHPM)上开展了深反射地震的同时,进行了大地电磁、地磁、放射性测量和重磁编图.本文介绍用这些方法取得的结果.两条区域性的地球物理剖面总长126km,经过二维反演取得了电阻率和磁性体剖面.结果表明:(1)大地电磁等综合地球物理资料与深反射地震剖面的推断结果基本一致,同样反映了UHPM岩块的俯冲折返与后期的隆升.(2)非地震地球物理资料不仅为地震解释提供约束,还可以提供地热流上涌、断裂和磁性体分布等更多的信息.(3)新发现莒南-海州北北西向断裂,对研究本区构造演化有重要意义.(4)根据地热流上涌、侵入体多和高波速体埋藏较深等特征,认为在本区进行科学钻探不够理想. 相似文献
970.