全文获取类型
收费全文 | 1624篇 |
免费 | 823篇 |
国内免费 | 442篇 |
专业分类
测绘学 | 56篇 |
大气科学 | 74篇 |
地球物理 | 296篇 |
地质学 | 1881篇 |
海洋学 | 153篇 |
天文学 | 30篇 |
综合类 | 99篇 |
自然地理 | 300篇 |
出版年
2024年 | 10篇 |
2023年 | 17篇 |
2022年 | 52篇 |
2021年 | 111篇 |
2020年 | 89篇 |
2019年 | 100篇 |
2018年 | 93篇 |
2017年 | 71篇 |
2016年 | 103篇 |
2015年 | 96篇 |
2014年 | 108篇 |
2013年 | 186篇 |
2012年 | 127篇 |
2011年 | 109篇 |
2010年 | 89篇 |
2009年 | 129篇 |
2008年 | 103篇 |
2007年 | 114篇 |
2006年 | 119篇 |
2005年 | 108篇 |
2004年 | 97篇 |
2003年 | 82篇 |
2002年 | 94篇 |
2001年 | 84篇 |
2000年 | 86篇 |
1999年 | 70篇 |
1998年 | 77篇 |
1997年 | 56篇 |
1996年 | 57篇 |
1995年 | 46篇 |
1994年 | 44篇 |
1993年 | 34篇 |
1992年 | 34篇 |
1991年 | 22篇 |
1990年 | 21篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 5篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1972年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有2889条查询结果,搜索用时 62 毫秒
41.
42.
金刚石中分子氢的赋存状态研究 总被引:1,自引:0,他引:1
金刚石中分子氢的定向红外光谱研究表明在垂直于(100),(110)和(111)三个方向上所测得分子氢的浓度是不相同的,且不同样品中的变化趋势也不同,即分子氢在金刚石中的定向性不明显;MNDO法计算结果显示分子氢在金刚石中的稳定程度大小关系依次为沿〈111〉定向的键心与反键心组合(a.b+b.c)〉六角体空隙(H)〉四面体空隙(T1)〉菱形中心(C1=C2)〉四面体空隙(T2). 相似文献
43.
SHI Nicheng BAI Wenji MA Zhesheng FANG Qingsong XIONG Ming YAN Binggang DAI Mingquan YANG JingsuiChina University of Geosciences Beijing E-mail: shinicheng@a-l.net.cn Institute of Geology Chinese Academy of Geological Sciences Beijing Liu Shuchun Zhu Xiling 《《地质学报》英文版》2003,77(3):326-331
Diamond was found in podiform chromitites of ophiolite and harzburgite from Luobusha, Tibet. There are silicate inclusions in some diamond grains from this area. In the present work, the CCD (charge coupled detector) technology of X-ray powder diffraction was applied to the study of the inclusion in diamond from the ophiolite of Tibet. Diffraction patterns are obtained even though the inclusion is only 20 μm in crystal size. The results show that the inclusion in diamond consists of talc and clinochrysotile. Therefore, it is clear that the diamond from the ophiolite of Luobusha, Tibet, is natural diamond rather than a synthetic one. 相似文献
44.
PAN Mingbao ZHANG Qinglong LU Huafu CHEN Huogen CHEN Shoujuand ZHU ShipengDepartment of Earth Sciences Nanjing University Nanjing Jiangsu Jiangsu Institute of Geological Survey Zhujiang Ro Nanjing Jiangsu E-mail: andypans@.com Hao Ziguo Zhu Xiling 《《地质学报》英文版》2003,77(3):332-337
From Donghai County of Jiangsu Province to Rongcheng County of Shandong Province on the southern border of the Sulu orogen, there exposes an ultramafic belt, accompanied with an ultrahigh-pressure metamorphic zone. It can be further divided into the Xugou belt (the northern belt), and the Maobei-Gangshang belt (the southern belt). One grain of diamond has been discovered from the Zhimafang pyrope peridotite in the southern belt using the heavy mineral method. The diamond grain is 2.13 mm × 1.42 mm × 0.83 mm in size and weighs 9.4 mg. The occurrence of the diamond suggests that the Zhimafang pyrope peridotite xenolith is derived from the lithospheric upper mantle. The tectonic emplacement mechanism of the pyrope peridotite xenoliths in granite-gneisses is obviously different from those in kimberlite. The Sulu orogen was located on the active continental margin of the Sino-Korean craton in the Neoproterozoic. The relatively cold and water-bearing oceanic crustal tholeiite slab subducted beneath the lith 相似文献
45.
出露于康定跑马山、丹巴格宗、公差等地的变质核杂岩地层,原岩为中酸性—中基性火山岩及沉积岩,经混合岩化及花岗岩化作用,形成一套正片麻岩及副片麻岩地层。获得1585—2341Ma原岩成岩同位素年龄值。应属康定群,时代为中元古代—太古代,为康滇地轴扬子地台结晶基底向北露头的延伸。 相似文献
46.
47.
48.
49.
50.
T.W. Foresman T. Cary T. Shupin R. Eastman J.E. Estes N. Faust J.R. Jensen K.K. Kemp 《ISPRS Journal of Photogrammetry and Remote Sensing》1997,52(6):294-300
The Remote Sensing Core Curriculum (RSCC) was initiated in 1993 to meet the demands for a college-level set of resources to enhance the quality of education across national and international campuses. The American Society of Photogrammetry and Remote Sensing adopted the RSCC in 1996 to sustain support of this educational initiative for its membership and collegiate community. A series of volumes, containing lectures, exercises, and data, is being created by expert contributors to address the different technical fields of remote sensing. The RSCC program is designed to operate on the Internet taking full advantage of the World Wide Web (WWW) technology for distance learning. The issues of curriculum development related to the educational setting, with demands on faculty, students, and facilities, is considered to understand the new paradigms for WW-influenced computer-aided learning. The WWW is shown to be especially appropriate for facilitating remote sensing education with requirements for addressing image data sets and multimedia learning tools. The RSCC is located at http://www.umbc.edu/rscc 相似文献