全文获取类型
| 收费全文 | 111篇 |
| 免费 | 11篇 |
| 国内免费 | 4篇 |
专业分类
| 测绘学 | 5篇 |
| 大气科学 | 3篇 |
| 地球物理 | 82篇 |
| 地质学 | 22篇 |
| 海洋学 | 12篇 |
| 天文学 | 2篇 |
出版年
| 2013年 | 2篇 |
| 2012年 | 4篇 |
| 2011年 | 10篇 |
| 2008年 | 8篇 |
| 2007年 | 5篇 |
| 2006年 | 2篇 |
| 2005年 | 5篇 |
| 2004年 | 11篇 |
| 2003年 | 9篇 |
| 2002年 | 8篇 |
| 2001年 | 5篇 |
| 2000年 | 4篇 |
| 1999年 | 3篇 |
| 1998年 | 8篇 |
| 1997年 | 7篇 |
| 1996年 | 4篇 |
| 1995年 | 3篇 |
| 1994年 | 3篇 |
| 1993年 | 8篇 |
| 1992年 | 2篇 |
| 1991年 | 8篇 |
| 1990年 | 3篇 |
| 1989年 | 1篇 |
| 1987年 | 2篇 |
| 1979年 | 1篇 |
排序方式： 共有126条查询结果，搜索用时 93 毫秒
91.
Bacterial mineralization patterns in basaltic aquifers: implications for possible life in martian meteorite ALH84001 总被引：1，自引：0，他引：1
Thomas-Keprta KL McKay DS Wentworth SJ Stevens TO Taunton AE Allen CC Coleman A Gibson EK Romanek CS 《Geology》1998,26(11):1031-1034
To explore the formation and preservation of biogenic features in igneous rocks, we have examined the organisms in experimental basaltic microcosms using scanning and transmission electron microscopy. Four types of microorganisms were recognized on the basis of size, morphology, and chemical composition. Some of the organisms mineralized rapidly, whereas others show no evidence of mineralization. Many mineralized cells are hollow and do not contain evidence of microstructure. Filaments, either attached or no longer attached to organisms, are common. Unattached filaments are mineralized and are most likely bacterial appendages (e.g., prosthecae). Features similar in size and morphology to unattached, mineralized filaments are recognized in martian meteorite ALH84001. 相似文献
92.
许多碳酸盐地台都有着不同程度的白云石化作用，白云石化作用的机理至今仍有争议、在许多例子中，白云石出现于沉积物成岩历史的早期阶段，但在埋藏过程中常有重结晶作用，因此，许多化学标志如同位素、痕量元素和有序度发生重排，不再反映形成白云石的原始孔隙流体的成分（Hardie，1987）。Urgonian地台位于法国Subal…ne山脉北部，这条山脉是一个位于法国东南部的NE─SW向这山带，部分为西阿尔卑斯的延伸带。Subalpine山脉包括了所有在Daupinois／Helvetlc盆地、Jura／BasDauphine他台和Provencal他台沉积的沉积物。该地区是被动边… 相似文献
93.
研究震源参数与震级之间的定量关系停留在相关统计上是不够的。震源参数与震级之间可能存在着确定性的函数关系(物理关系)。本文利用76个云南地震(4.0≤M_s≤5.8)数据,得到了一组互相一致的云南地震震源参数与面波震级 M_s 的函数关系:M_s=lgM_o-lgr-17.94 s=±0.32M_s=lg△σ+lgA+2.92 s=±0.33M_s=lg(?)+lgr+4.04 s=±0.33式中地震矩 M_o、地震应力降△σ、震源破裂面半径 r、面积 A 及平均断错(?)的单位,分别为达因·厘米、巴、公里、平方公里和厘米。s 为剩余标准差。 相似文献
94.
95.
96.
本文研讨了在详细地设计冶炼实验和处理难选金矿石的最佳条件中,金矿物学平衡的意义。通过对32个金矿石和含金矿石的实验而得到了一个完整的定量化的矿物学平衡程序。这个平衡程序是以特殊的氧化作用用鉴定可见金的百分比和用光学显微镜及电子探针测定金矿物的特征为基础提出的。不可见金即胶体粒级金和固体中的金,这两者直接用氧化作用选剔测定效果不佳,用定量的离子探针微区分析(SIMS)可直接测定。这样就直接测定了所有的载金矿物,鉴定结果准确无误。本文选择五个例子作了介绍。目的之一是提供一个体系——通过鉴定金的赋存形式来研究金的矿物学程序,并有助于设计和优化选矿工艺过程。 相似文献
97.
Apatite fission-track ages of 168-83 Ma for 39 samples of Proterozoic crystalline rocks, three samples of Cambrian Potsdam sandstone, and one Cretaceous lamprophyre dike from the Adirondack Mountains in New York State indicate that unroofing in this region occurred from Late Jurassic through Early Cretaceous. Samples from the High Peaks section of the Adirondack massif yielded the oldest apatite fission-track ages (168-135 Ma), indicating that it was exhumed first. Unroofing along the northern, northwestern, and southwestern margins of the Adirondacks began slightly later, as shown by younger apatite fission-track ages (146-114 Ma) determined for these rocks. This delay in exhumation may have resulted from burial of the peripheral regions by sediment shed from the High Peaks. Apatite fission-track ages for samples from the southeastern Adirondacks are distinctly younger (112-83 Ma) than those determined for the rest of the Adirondack region. These younger apatite fission-track ages are from a section of the Adirondacks dissected by shear zones and post-Ordovician north-northeast-trending normal faults. Differential unroofing may have been accommodated by reactivation of the faults in a reverse sense of motion with maximum compressive stress, sigma1, oriented west-northwest. A change in the orientation of the post-Early Cretaceous paleostress field is supported by a change in the trend of Cretaceous lamprophyre dikes from east-west to west-northwest. 相似文献
98.
Relocation of the 1998 Zhangbei-Shangyi earthquake sequence using the double difference earthquake location algorithm 总被引：4，自引：0，他引：4
Introduction On January 10, 1998, at 11h50min Beijing Time (03h50min UTC), an earthquake of ML=6.2 occurred in the border region between the Zhangbei County and Shangyi County of Hebei Province. In total 87 events with ML3.0 were recorded by Beijing Telemetry Seismic Network (BTSN) before March of 1999. Before relocation the preliminary hypocenters determined by BTSN showed an epicentral distribution of 25 km long and 25 km wide without any predominate orientation. The epicentral a… 相似文献
99.
引言报道了对最近发生的加利福尼亚中部2003年12月22日圣西蒙6.5级地震在震前所做的成功的预报。有关这一预报意见的报告是在地震前6个月,即2003年6月 相似文献
100.