全文获取类型
收费全文 | 814篇 |
免费 | 388篇 |
国内免费 | 171篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 30篇 |
地球物理 | 287篇 |
地质学 | 847篇 |
海洋学 | 36篇 |
天文学 | 6篇 |
综合类 | 98篇 |
自然地理 | 55篇 |
出版年
2023年 | 8篇 |
2022年 | 43篇 |
2021年 | 68篇 |
2020年 | 52篇 |
2019年 | 68篇 |
2018年 | 54篇 |
2017年 | 47篇 |
2016年 | 42篇 |
2015年 | 55篇 |
2014年 | 83篇 |
2013年 | 71篇 |
2012年 | 79篇 |
2011年 | 72篇 |
2010年 | 73篇 |
2009年 | 89篇 |
2008年 | 49篇 |
2007年 | 64篇 |
2006年 | 55篇 |
2005年 | 58篇 |
2004年 | 29篇 |
2003年 | 30篇 |
2002年 | 22篇 |
2001年 | 28篇 |
2000年 | 16篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有1373条查询结果,搜索用时 576 毫秒
1.
Inessa V. Golovanova Robert N. Harris Galina V. Selezniova Petr Stulc 《Global and Planetary Change》2001,29(3-4)
Thirty borehole temperature–depth profiles in the central and southern Urals, Russia were scrutinized for evidence of ground surface temperature histories. We explored two inversion schemes: a simple ramp inversion in which solutions are parameterized in terms of an onset time and magnitude of change and a more sophisticated functional space inverse algorithm in which the functional form of the solution is left unspecified. To enhance and potentially identify latitudinal differences in the ground surface temperature signal, we subdivided the data into three groups based on geographic proximity and simultaneously inverted the borehole temperature–depth logs. The simultaneous inversions highlighted 13 temperature–depth logs that could not both fit a common ground surface temperature history and a priori models within reasonable bounds. Our results confirm that this is an effective way to reduce site-specific noise from an ensemble of boreholes. Each inversion scheme gives comparable results indicating locally variable warming on the order of 1°C starting between 1800 and 1900 AD. Similarly surface air temperature records from 12 nearby meteorological stations exhibit locally variable warming also on the order of 1°C of warming during the 20th century. To explore the degree to which borehole temperatures and surface air temperature (SAT) time series are responding to the same signal, we average the SAT data into the same three groups and used these averages as a forcing function at the Earth's surface to generate synthetic transient temperature profiles. Root mean square (RMS) misfits between these synthetic temperature profiles and averaged temperature–depth profiles are low, suggesting that first-order curvature in borehole temperatures and variations in SAT records are correlated. 相似文献
2.
Laura Chiaramonte Mark D. Zoback Julio Friedmann Vicki Stamp 《Environmental Geology》2008,54(8):1667-1675
This paper reports a preliminary investigation of CO2 sequestration and seal integrity at Teapot Dome oil field, Wyoming, USA, with the objective of predicting the potential risk
of CO2 leakage along reservoir-bounding faults. CO2 injection into reservoirs creates anomalously high pore pressure at the top of the reservoir that could potentially hydraulically
fracture the caprock or trigger slip on reservoir-bounding faults. The Tensleep Formation, a Pennsylvanian age eolian sandstone
is evaluated as the target horizon for a pilot CO2 EOR-carbon storage experiment, in a three-way closure trap against a bounding fault, termed the S1 fault. A preliminary geomechanical
model of the Tensleep Formation has been developed to evaluate the potential for CO2 injection inducing slip on the S1 fault and thus threatening seal integrity. Uncertainties in the stress tensor and fault
geometry have been incorporated into the analysis using Monte Carlo simulation. The authors find that even the most pessimistic
risk scenario would require ∼10 MPa of excess pressure to cause the S1 fault to reactivate and provide a potential leakage
pathway. This would correspond to a CO2 column height of ∼1,500 m, whereas the structural closure of the Tensleep Formation in the pilot injection area does not exceed
100 m. It is therefore apparent that CO2 injection is not likely to compromise the S1 fault stability. Better constraint of the least principal stress is needed to
establish a more reliable estimate of the maximum reservoir pressure required to hydrofracture the caprock. 相似文献
3.
Two algorithms for in-situ detection and identification of vertical free convective and double-diffusive flows in groundwater
monitoring wells or boreholes are proposed. With one algorithm the causes (driving forces) and with the other one the effects
(convection or double-diffusion) of vertical transport processes can be detected based on geophysical borehole measurements
in the water column. Five density-driven flow processes are identified: thermal, solutal, and thermosolutal convection leading
to an equalization, as well as saltfingers and diffusive layering leading to an intensification of a vertical density gradient.
The occurrence of density-driven transport processes could be proven in many groundwater monitoring wells and boreholes; especially
shallow sections of boreholes or groundwater monitoring wells are affected dramatically by such vertical flows. Deep sections
are also impaired as the critical threshold for the onset of a density-driven flow is considerably low. In monitoring wells
or boreholes, several sections with different types of density-driven vertical flows may exist at the same time. Results from
experimental investigations in a medium-scale testing facility with high aspect ratio (height/radius = 19) and from numerical
modeling of a water column agree well with paramters of in-situ detected convection cells. 相似文献
4.
介绍了目前滑坡深部水平位移钻孔倾斜仪人工监测方法存在的问题,钻孔深部位移自动化监测通信方法的选择。地质滑坡灾害监测中广泛使用钻孔倾斜仪,介绍了CZ-2型钻孔倾斜仪的构成及现场测试方法。 相似文献
5.
6.
7.
基于分布式检测与决策融合的海底油气管线检漏 总被引:3,自引:0,他引:3
利用多传感器的信息融合思想,提出分布式检测与决策融合方法进行长距离海底管线泄漏监测。试验水管和天然气/凝析油管线现场数据分析表明此算法不仅降低了误报警概率,且对流体在输送过程中动态变化具有稳健性。 相似文献
8.
基于钻孔数据的三维地质建模与可视化研究 总被引:8,自引:1,他引:7
三维地质模型能够完整准确地表达复杂地质现象的边界条件及地质体内含的各种地质构造,直观地再现地质单元的空间展布及其相互关系,最大限度地提高地质分析的直观性和准确性,因此三维地质建模已引起地质、采矿、岩土工程等诸多领域的日益重视。笔者在综合考察多种建模方法的基础上,结合工程实践,提出了一种实用的工程地质三维建模实施方法。该方法以钻孔资料和地质剖面数据为三维地质建模的源数据,允许用户手工修正模型剖面地层分界线,从而实现对建模过程的干预和控制,克服了单纯依靠钻孔数据建模结果不精确且难以修正的问题。最后,通过一个研究实例展示了该方法的实际建模效果。 相似文献
9.
海底泉在滨海地下水排泄过程中起着重要的作用。本文给出了含有一个海底泉的在海底延伸的越流承压含水层系统中地下水水头在海潮作用下波动的近似解析解。该含水层顶底板隔水且向海底延伸有限距离。假设含水层的海底露头被一层隔水层覆盖,海底泉由一个渗透性很好的完全穿透海底含水层硕板的圆柱体渗漏天窗(海底泉孔)来表示。近似解析解中包含了6个参数:承压含水层的海潮传播参数,海底泉孔中心到海岸线的距离,表示泉的圆柱体的等效半径,海底泉孔中心到含水层海底露头处的距离,承压含水层的海潮载荷效率和弱透水层的越流。分析表明,如果海底泉孔中心到海岸线的距离远大于泉孔的等效半径,且海底泉孔中心到含水层海底露头处的距离远大于泉孔的等效半径时,解析解的近似误差可以忽略。然后本文讨论了解析解的两个基本性质,分析了海底泉对海底地下水水头波动的影响。 相似文献
10.
平朔公司安太堡三号井工矿2007年3月在首采工作面辅运顺槽掘进时,迎头冒顶突水,初期突水量达6000~8000m^3/d,将1289.16m标高以下淹没。在分析研究区地层、构造及水文地质条件的基础上,对沙沟河道进行了渗漏观测,对地表排污水、沟水和井下突水点的水质进行了分析化验,有针对性的布置了6条物探线,最后进行了钻孔验证,综合分析认为突水水源主要为大沙沟河道的侧向补给,突水通道为NW向的强风化带。提出了加大井下排水,地表对大沙沟河进行土工膜防渗处理的综合治理措施。 相似文献