全文获取类型
收费全文 | 2413篇 |
免费 | 344篇 |
国内免费 | 466篇 |
专业分类
测绘学 | 78篇 |
大气科学 | 32篇 |
地球物理 | 853篇 |
地质学 | 1878篇 |
海洋学 | 137篇 |
天文学 | 3篇 |
综合类 | 79篇 |
自然地理 | 163篇 |
出版年
2024年 | 33篇 |
2023年 | 84篇 |
2022年 | 82篇 |
2021年 | 82篇 |
2020年 | 106篇 |
2019年 | 120篇 |
2018年 | 98篇 |
2017年 | 161篇 |
2016年 | 142篇 |
2015年 | 111篇 |
2014年 | 138篇 |
2013年 | 163篇 |
2012年 | 149篇 |
2011年 | 190篇 |
2010年 | 158篇 |
2009年 | 159篇 |
2008年 | 149篇 |
2007年 | 146篇 |
2006年 | 117篇 |
2005年 | 118篇 |
2004年 | 75篇 |
2003年 | 72篇 |
2002年 | 66篇 |
2001年 | 57篇 |
2000年 | 46篇 |
1999年 | 56篇 |
1998年 | 54篇 |
1997年 | 52篇 |
1996年 | 49篇 |
1995年 | 31篇 |
1994年 | 29篇 |
1993年 | 26篇 |
1992年 | 38篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有3223条查询结果,搜索用时 15 毫秒
61.
岩相和储层物性参数是油藏表征的重要参数,地震反演是储层表征和油气藏勘探开发的重要手段.随机地震反演通常基于地质统计学理论,能够对不同类型的信息源进行综合,建立具有较高分辨率的储层模型,因而得到广泛关注.其中,概率扰动方法是一种高效的迭代随机反演策略,它能综合考虑多种约束信息,且只需要较少的迭代次数即可获得反演结果.在概率扰动的优化反演策略中,本文有效的联合多点地质统计学与序贯高斯模拟,并结合统计岩石物理理论实现随机反演.首先,通过多点地质统计学随机模拟,获得一系列等可能的岩相模型,扰动更新初始岩相模型后利用相控序贯高斯模拟建立多个储层物性参数模型;然后通过统计岩石物理理论,计算相应的弹性参数;最后,正演得到合成地震记录并与实际地震数据对比,通过概率扰动方法进行迭代,直到获得满足给定误差要求的反演结果.利用多点地质统计学,能够更好地表征储层空间特征.相控序贯高斯模拟的应用,能够有效反映不同岩相中储层物性参数的分布.提出的方法可在较少的迭代次数内同时获得具有较高分辨率的岩相和物性参数反演结果,模型测试和实际数据应用验证了方法的可行性和有效性.
相似文献62.
为了确定百花水库营养盐变化特征,选取百花水库5个监测点2014年1月-2018年7月共28个月份的水质实测数据,分析溶解氧、高锰酸盐指数、氨氮、总磷和总氮的年际变化特征.采用基于熵权法赋权的贝叶斯理论对5个监测点的水质综合状况进行评价,并结合水库的实际状况,从生态修复、工业污染源、沉积物中营养盐、水库季节性热分层及农业与生活污染源5个方面对其水质变化的影响因素进行分析.结果表明:2014-2018年水体环境波动较大;除总氮外,各污染指标浓度均有不同程度的下降;综合水质后验概率表明百花水库水质有逐渐变差的趋势;总氮和总磷治理应成为百花水库污染治理的主要方面;生态修复工程的开展和工业污染源的削减是百花水库水质转好的主要影响因素,农业与生活污染源的增加是百花水库水质转差的主要影响因素. 相似文献
63.
64.
Franz May Stephan Hoernes Horst J. Neugebauer 《International Journal of Earth Sciences》1996,85(4):782-799
Three major, interdependent processes control the genesis and distribution of mineral and thermal waters in the Rhenish Massif,
Central Europe: (a) Magmatic processes in the upper mantle provide most of the CO2 to produce bicarbonate waters in shallow aquifers. (b) Extension of the brittle upper crust enables the ascent of sodium
chloride waters. (c) Uplift and erosion shape the massif's relief, which determines the extent of flow systems and the distribution
of thermal springs. The chemistry of mineral waters further depends on the aquifers' mineral composition. A comprehensive
set of hydrological, chemical, tectonic and geophysical data on the Rhenish Massif has been compiled. It was used to classify
the mineral waters and to map the spatial distribution of water properties. The composition of cuttings from several representative
wells producing different water types shows that the hydrothermal alteration of the aquifer rocks consists mainly of kaolinization
of chlorite and dissolution of feldspar. Numerical transport simulations favour two modes of groundwater flow: topography-driven
flow and the pressure-driven ascent of basement brines along active faults. Thermal convection is less important. 相似文献
65.
Satoshi Noguchi Naoyuki Shimoda Osamu Takano Nobutaka Oikawa Takao Inamori Tatsuo Saeki Tetsuya Fujii 《Marine and Petroleum Geology》2011,28(10):1817-1828
The reservoir architecture of methane hydrate (MH) bearing turbidite channels in the eastern Nankai Trough, offshore Japan is evaluated using a combination of 3-D seismic and well data. On the 3-D seismic section, the MH-bearing turbidite channels correspond to complex patterns of strong seismic reflectors, which show the 3-D internal architecture of the channel complex. A seismic-sequence stratigraphic analysis reveals that the channel complex can be roughly classified into three different stages of depositional sequence (upper, middle, and lower). Each depositional sequence results in a different depositional system that primarily controls the reservoir architecture of the turbidite channels. To construct a 3-D facies model, the stacking patterns of the turbidite channels are interpreted, and the reservoir heterogeneities of MH-bearing sediments are discussed. The identified channels at the upper sequence around the β1 well exhibit low-sinuosity channels consisting of various channel widths that range from tens to several hundreds of meters. Paleo-current flow directions of the turbidite channels are typically oriented along the north-northeast-to-south-southwest direction. High-amplitude patterns were identified above the channels along the north-to-south and north-northeast-to-south-southeast directions. These roughly coincide with the paleo-current flow of the turbidite channels. An interval velocity using high-density velocity analysis shows that velocity anomalies (>2000 m/s) are found on the northeastern side of the turbidite channels. The depositional stage of the northeastern side of the turbidite channels exhibits slightly older sediment stages than the depositional stages of the remaining channels. Hence, the velocity anomalies of the northeastern side of the channels are related to the different stages of sediment supply, and this may lead to the different reservoir architectures of the turbidite channels. 相似文献
66.
67.
S. Grassmann B. Cramer G. Delisle T. Hantschel J. Messner J. Winsemann 《Marine and Petroleum Geology》2010
During the past two million years low surface temperatures as well as episodically advancing ice sheets from Scandinavia acted on the subsurface pT-regime of northern Germany. Their likely effects on the petroleum system of Schleswig-Holstein were investigated. For the entire Quaternary mean annual ground temperature (MAGT) was reconstructed at a resolution of 1000 years by calibrating oxygen isotope records from ODP-site 659 to the climate of northern Germany of the past 120 kyr. The resulting MAGT trend served as input to an ice sheet model and a permafrost model along a 2D section crossing the petroleum bearing south-western part of Schleswig-Holstein. Here advances and retreats of the Scandinavian ice sheet during Saalian and Elsterian glaciation Stages were reconstructed. Maximum ice thicknesses of up to 1700 m and up to 20 periods of regional permafrost in northern Germany were reconstructed for the past 1.25 million years. Based on a basal heat flow of 50 mW/m2 permafrost thicknesses exceeded 100 m during most of these periods, temporarily extending down to depths of more than 300 m. Favourable surface temperatures and long durations of cold periods provided favourable conditions for onshore gas hydrate stability zones at Mittelplate. Implementing these glacial dynamics into 2D basin modelling (PetroMod, IES, Aachen, Germany) of the Mittelplate oil field reveals five phases of gas hydrate stability at depths down to 750 m. The latest of these events occurred during the Weichselian about 20 kyr ago. The effect of the ice sheets on pore pressure in the subsurface strongly depends on the hydraulic boundary conditions at the ice base (e.g. frozen vs. temperate ice sheet base). Excess pore pressure in the reservoir of more than 10 MPa during ice overriding is possible and probable. The calculated temperature effect of the Pleistocene cooling on the Mittelplate reservoir is in the range of 3–7 °C. Even today temperature in the reservoir is still lowered by about 4 °C in comparison to pre-Pleistocene times. Despite the fact that a significant influence of glacial effects on petroleum generation can be ruled out at Mittelplate, we state that pT-effects in reservoirs related to glacial processes in formerly glaciated areas have been underestimated in the past. 相似文献
68.
Reservoir potential of Late Cretaceous terrestrial to shallow marine sandstones,Taranaki Basin,New Zealand 总被引:2,自引:0,他引:2
Late Cretaceous coals and coaly source rocks are the main source of hydrocarbons in the Taranaki Basin, yet to date there have not been any hydrocarbon discoveries within Cretaceous strata, and sandstone distribution and reservoir quality for this interval have been poorly understood. The Late Cretaceous sediments were deposited in several sub-basins across Taranaki, with their distribution largely determined by sediment supply, subsidence, and sea level change. In this study, we describe potential reservoir facies in well penetrations of Cretaceous strata in Taranaki, as well as from outcrop in northwest Nelson, on the southern edge of the basin. 相似文献
69.
70.