全文获取类型
收费全文 | 127篇 |
免费 | 32篇 |
国内免费 | 63篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 9篇 |
地球物理 | 39篇 |
地质学 | 118篇 |
海洋学 | 16篇 |
天文学 | 24篇 |
综合类 | 7篇 |
自然地理 | 8篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 9篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有222条查询结果,搜索用时 15 毫秒
121.
122.
中国大陆科学钻探主孔100-2000m岩心的磁化率各向异性及其地质意义 总被引:1,自引:0,他引:1
在常温常压条件下获得了中国大陆科学钻探(CCSD)主孔331块岩心的磁化率各向异性(AMS)数据,并建立了主孔100—2000m的体积磁化率和AMS连续剖面。数据统计分析显示,主孔100—2000m岩心的磁化率(κ)介于1.05×10-4SI和0.12SI之间,几何平均值为1.855×10-3SI;磁化率各向异性度(Pj)介于1.04和2.10之间,几何平均值为1.155。该井段出露的主要岩石类型有榴辉岩、退变质榴辉岩、角闪岩、正片麻岩、副片麻岩和蛇纹石化橄榄岩,它们的垂向分布特征控制着磁化率剖面的变化。主孔的超高压变质岩石在折返过程中普遍经历了强烈的角闪岩相退变质作用的改造。其磁化率特征也发生相应的改变。蛇纹石化橄榄岩具有很高的磁化率(8.58×10-2SI)和各向异性度(1.335)。这主要源于橄榄岩蛇纹石化过程中产生的大量磁铁矿。榴辉岩、退变质榴辉岩和角闪岩代表榴辉岩从新鲜到完全退变质的三个阶段,它们的磁化率和磁化率各向异性度分别为榴辉岩(1.28×10-3SI、1.077)、退变质榴辉岩(3.19×10-3SI、1.206)、角闪岩(1.02×10-3SI、1.104)。正片麻岩的磁化率和各向异性度分别为5.34×10-3SI和1.167。副片麻岩的磁化率和各向异性度分别为3.46×10-4SI和1.150。对58个变形岩石的AMS测试结果显示,其磁化率椭球体的主轴方向与岩石组构基本一致,即最大磁化率主轴κ1平行矿物线理,最小磁化率主轴κ3垂直岩石面理。同时,这些变形岩石的AMS椭球体多呈现明显的压扁状特征,反映超高压变质岩石在折返过程中处于强烈挤压变形的构造应力环境,为苏鲁超高压变质板片的挤出折返模式提供了佐证。该研究成果也为超高压变质岩石地区磁学研究、地球物理调查和测井成果的解释提供了重要的实验约束。 相似文献
123.
冈底斯作为重要的中、新生代岛弧岩浆岩带,历来是青藏高原最热门的地质研究领域,但是对晚古生代火山岩的性质及其形成的构造背景仍缺乏研究。本文在区域地质调查资料的基础上,对冈底斯带石炭纪火山-沉积岩系进行了系统的地层学和岩石地球化学研究,测量了重点剖面,对火山岩进行了常量、微量元素和Sr、Nd、Pb同位素地球化学测试。研究表明,石炭系与下伏泥盆系或前寒武系之间普遍存在不整合或岩性、沉积相的突变面,代表重要的构造转换面。石炭纪的沉积环境大致有两次滨海-深海或深水斜坡-滨海沉积演化旋回,深海-深水斜坡沉积或冰海相含砾板岩与两次火山活动伴生。石炭纪火山岩主要为安山玄武岩和英安岩、流纹岩类,略具双峰式火山岩特点。安山玄武岩类的成分与典型MORB和岛弧玄武岩相比,具有MgO含量低,TiO2、Al2O3、P2O5含量高等特点,稀土和微量元素为LREE和LILE富集型分配模式,与大陆拉斑玄武岩相似。石炭纪酸性火山岩的稀土和微量元素地球化学特征与陆内流纹岩相似。岩石地球化学示踪和地层学研究表明,冈底斯带石炭纪为伸展背景下的冈瓦纳陆缘裂陷环境。火山岩的源区地幔具有典型的Dupal异常,发生过复杂的混合作用,涉及到原始地幔、富集地幔EMII和地壳成分等,说明发生过冈瓦纳古陆壳俯冲、再循环进入古老地幔等过程。玄武岩类成分的某些特殊性,可能与源区混合作用有关。 相似文献
124.
LI Jianping GAO Feng ZHANG Bai 《地球空间信息科学学报》2007,10(2):128-132
By using remote sensing images from three periods (1980, 1995, 2000) and with the support of GIS and RS, the spatial information of landscape elements of Jilin Province from 1980 to 2000 was interpreted and extracted. Using models of landscape indices such as diversity, fragmentation, and mean patch fractal dimension, dynamic spatio-temporal changes of landscape patterns of the province were analyzed. The results: ① cropland and forestland were the main landscape types, and forestland became a landscape matrix; ② in the study area, landscapes were distributed unevenly, and there was low heterogeneity, a simple ecosystem structure and a tendency of irrational landscape patterns. There were also simple spatial shapes of patches and strong self-similarities, and in terms of dynamic change analysis, patch shapes tended to be more simple; ③ from 1980 to 2000, holistic landscape fragmentation was low and changed slightly. As far as landscape elements were concerned, the fragmentation of grassland, water area, land for residential area and factory facilities was relatively low; land distribution for residential areas and factory facilities was dispersed; and cropland and forestland were most concentrated-an indication that the trend will continue. Comprehensive effects among human activity, local policy, regional climate and environmental change led to the results. 相似文献
125.
126.
INTRODUCTIONTheregularpatternsofmovementanddistributionofcurrentandsedimentinwaterbodyinestuaryandatcoastareconcernedbythepublicatalltime,butonlyafewresearchesonthenumericalsimulationofthethree-dimensionalnonlinearmovementoftideandwave,inwhichLeendertse's(Leendertseetal.,1973)finitedifferencemethod(FDM)istheleadingone,havebeendoneuptonow.TheLeendertseFDMisnotverygoodinitsapplication.Themainreasonisthatinthemodethesquaregridsinaplanecomputationaldomainareadopted.Thisgridsystemcannotfitt… 相似文献
127.
The Multi-channel Photometric Survey Telescope(Mephisto) is a real-time, three-color photometric system designed to capture the color evolution of stars and transients accurately. This telescope system can be crucial in cosmological distance measurements of low-redshift(low-z, z ■ 0.1) Type Ia supernovae(SNe Ia). To optimize the capabilities of this instrument, we perform a comprehensive simulation study before its official operation is scheduled to start. By considering the impact of atmospheri... 相似文献
128.
Due to differences in the properties of composition materials and construction techniques, unreinforced masonry is characterized by low strength, anisotropy, nonuniformity, and low ductility. In order to accurately simulate the mechanical behavior of unreinforced brick masonry walls under static and dynamic loads, a new elastoplastic damage constitutive model was proposed and the corresponding subroutine was developed based on the concrete material constitutive model. In the proposed constitutiv... 相似文献
129.
Weiwei Li Zhongqiao Li Zhuoyi Zhu Alexander Polukhin Youcheng Bai Yang Zhang Futao Fang Haiyan Jin Anatolii S.Astakhov Xuefa Shi Jianfang Chen 《海洋学报(英文版)》2023,(11):9-18
In the context of global warming and rapid environment change in the Arctic, the supply of organic matter(OM)has increased significantly and a large amount of OM are buried on the Arctic shelf. Studying the fate of OM in Arctic shelf sediments is crucial to understanding the global carbon sink. As a marginal sea of the Arctic Ocean,the Chukchi Sea is one of the most critical areas where OM is buried. Based on the surface sediment samples collected during the sixth Chinese National Arctic Researc... 相似文献
130.
In this paper,we conducted a regression analysis of the intensity distribution data of 146 earthquakes( M ≥ 5. 0) which occurred in the period from 1900 to 2014. According to previous research,Yunnan is divided into 3 tectonic regions. Then we use the data of the isoseismic lines in these 3 regions to fit the intensity-attenuation model of each region.Since there were a few M ≥ 7. 0 earthquakes in this 114-year period,the fitted intensityattenuation model of the strong earthquakes would be random or uncertain. To solve this problem,we introduce the Rupture Scale relationship to limiting our fitted intensityattenuation model of strong earthquakes. We choose the empirical relationship of magnitude and rupture-scale,which was proposed by Li Zhonghua and Qin Jiazheng,to correct the size of the influence field estimated through our intensity-attenuation model.Comparing our intensity-attenuation models with the previous ones, we find that in a certain tectonic region,the intensity isoseismals estimated through our model have average minimum error with the real intensity isoseismal decided through field investigation.Therefore,it is more advisable to choose the small-scale zone for the intensity-attenuation evaluation. 相似文献