全文获取类型
收费全文 | 417篇 |
免费 | 67篇 |
国内免费 | 135篇 |
专业分类
测绘学 | 57篇 |
大气科学 | 62篇 |
地球物理 | 37篇 |
地质学 | 284篇 |
海洋学 | 59篇 |
天文学 | 4篇 |
综合类 | 56篇 |
自然地理 | 60篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 18篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 40篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 18篇 |
2009年 | 28篇 |
2008年 | 15篇 |
2007年 | 26篇 |
2006年 | 7篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 16篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 12篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有619条查询结果,搜索用时 15 毫秒
11.
云南老王寨金矿煌斑岩地球化学研究中的某些问题──与宋新宇等同志商榷 总被引:2,自引:0,他引:2
本文对“云南老王寨金矿煌斑岩地球化学研究”一文中的部分结论及其解释,提出一些不同意见与原文作者宋新宇等先生商榷 相似文献
12.
云南老王寨金矿区煌斑岩的成因:稀土元素研究 总被引:6,自引:0,他引:6
云南老王寨金矿区煌斑岩与金矿化在时间上、空间上密切共生。主要元素分析表明,本区煌斑岩属钾质-富钾质钙碱性煌斑岩;与原始地幔和大洋中脊玄武岩相比,岩石相对富集稀土元素;模拟计算表明,岩石来源于稀土元素相对富集的交代富集地幔;地质发展史、不相容元素分配型式、Sr、Nd同位素组成及有关模拟计算表明,俯冲进入地幔楔的地壳物质脱水 流体是引起该区地幔交代作用的主要因素。 相似文献
13.
曲边冰洲石的发现及其矿床成因的探讨 总被引:2,自引:0,他引:2
在各类型冰洲石矿床中发现了大量的冰洲石弯晶,通过冰洲石矿床野外考察的归纳总结,联系到晶体生长和材料力学的有关知识,提出冰州石矿床的成因极可能是原矿床中方解石受到的构造运动强烈影响后,在长期的水淋滤改造作用下发生冰洲石化,并由此而形成冰洲石矿床。 相似文献
14.
本文对Ni40Mn30Fe30合金与在不同焙烧温度下得到的含水叶蜡,在高温超高压下的反应进行了实验研究,温度测至1420℃,压是至5.5GPa,研究了该反应的物质-化学机制,以及反应速率与温度,压力,含水量等参数的关系,对高压下物质迁移运动的固有特征进行了探讨。 相似文献
15.
is paper is concerned with the geochemical features of major elements,transition metal elements,large ion lithophile elements,rare-earth elements and Sr isotopes in alkaline-ul-trabasic rocks in the Jijie complex of Lufeng,Yunnan Province,which is located in southern Sichuan-Yunnan rift zone,one of Luoci alkaline-ultrabasic complexes in central Ynnnan,Moreover,its origin pertaining primary magma,magma soure region,fractional crystallization,etc.are also discussed in the present paper. 相似文献
16.
采用最新研制的岩体应力、应变匹配传感器对西安立井煤柱开采引起的井筒附加应力特别是对井筒穿过断层附近产生的附加应力进行了较系统的观测,并对观测结果进行了分析和总结。 相似文献
17.
Characteristics of dynamic equilibrium for natural gas migration and accumulation of the gas field in the center of the Ordos Basin 总被引:3,自引:0,他引:3
The gas field in the center of Ordos Basin has been conventionally considered as a large gas pool with thin reservoirs. However,
lots of phenomena contrary to this concept occur in the exploration and production process. It is proposed that the gas field
is composed of many small lithological gas pools, sourced from and reservoired in the same Ordovician formation which is an
underpressured fluid compartment. A dynamic equilibrium moldel of natural gas migration and accumulation has been developed
to illustrate the formation mechanism of these gas pools. 相似文献
18.
TheHuizelarge sizedPb ZndepositinYunnan ProvinceislocatedinthecenteroftheSichuan Yun nan GuizhouPb Zn Agpolymetalmineralizationzone(SYGPb ZnMMD)inwesternYangtzePlateandis oneofthefamousPb Zn GebasesinChina(Wang Jiangzhenetal.,2003;WangXiaochunetal.,2000).Thisdeposit,whichischaracterizedbylarge scale(Pb+Znmetallicreservesarehigherthan5mil liontons),highPb+Zngrade(thePb+Zngradesof mostoresare25%-35%),highabundanceofuseful associatedelements(Ag,Ge,Cd,Ga,etc.)and someimportantbreakt… 相似文献
19.
Yue Ma Xiao‐Hui Chen Lee J. Hosking Hai‐Sui Yu Hywel R. Thomas Simon Norris 《国际地质力学数值与分析法杂志》2021,45(1):64-82
Coupled thermo‐hydro‐mechanical‐chemical modelling has attracted attention in past decades due to many contemporary geotechnical engineering applications (e.g., waste disposal, carbon capture and storage). However, molecular‐scale interactions within geomaterials (e.g., swelling and dissolution/precipitation) have a significant influence on the mechanical behaviour, yet are rarely incorporated into existing Thermal‐Hydro‐Mechanical‐Chemical (THMC) frameworks. This paper presents a new coupled hydro‐mechanical‐chemical constitutive model to bridge molecular‐scale interactions with macro‐physical deformation by combining the swelling and dissolution/precipitation through an extension of the new mixture‐coupling theory. Entropy analysis of the geomaterial system provides dissipation energy, and Helmholtz free energy gives the relationship between solids and fluids. Numerical simulation is used to compare with the selected recognized models, which demonstrates that the swelling and dissolution/precipitation processes may have a significant influence on the mechanical deformation of the geomaterials. 相似文献
20.
Previous work on three‐dimensional shakedown analysis of cohesive‐frictional materials under moving surface loads has been entirely for isotropic materials. As a result, the effects of anisotropy, both elastic and plastic, of soil and pavement materials are ignored. This paper will, for the first time, develop three‐dimensional shakedown solutions to allow for the variation of elastic and plastic material properties with direction. Melan's lower‐bound shakedown theorem is used to derive shakedown solutions. In particular, a generalised, anisotropic Mohr–Coulomb yield criterion and cross‐anisotropic elastic stress fields are utilised to develop anisotropic shakedown solutions. It is found that shakedown solutions for anisotropic materials are dominated by Young's modulus ratio for the cases of subsurface failure and by shear modulus ratio for the cases of surface failure. Plastic anisotropy is mainly controlled by material cohesion ratio, the rise of which increases the shakedown limit until a maximum value is reached. The anisotropic shakedown limit varies with frictional coefficient, and the peak value may not occur for the case of normal loading only. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献