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741.
Molecular dynamics simulations employing a many-body embedding potential model have been conducted to calculate both bulk
and shear viscosity of pure liquid iron at the Earth's outer core conditions. Liquid iron shear viscosity thus obtained is
in the order of 10−2 Pa · s and is in close agreement with previous estimates. In contrast, liquid iron bulk viscosity is in the order of 10−3 to 10−4 Pa · s and is much smaller than previous estimates. Consequently, the ratio of bulk to shear viscosity is close to 0.1. This
value disagrees with both the common speculation that bulk and shear viscosities are equal at ambient pressure, and the previous
inference that bulk viscosity of liquid iron is much larger than shear viscosity at outer core conditions. Potential implications
of present data are also briefly given for the dynamic state of the outer core.
Received: 9 April 1999 / Revised, accepted: 7 June 1999 相似文献
742.
通过录井、测井、地震、野外剖面与岩心资料的深入剖析, 探讨中上扬子地区下志留统页岩段的沉积相与总有机碳的关系, 预测页岩气有利勘探区。中上扬子地区下志留统龙马溪组为一套20~268 m厚的黑色页岩夹灰绿色泥质粉砂岩沉积, 在等时框架内自下而上可识别出2个三级层序即SQ1与SQ2, 它们分布稳定、可对比性好。下部层序(SQ1) 的海侵体系域(TST)发育一套有利于页岩气形成的富有机质页岩, 此时期呈现出“北面向次深海敞开、东西南三面受古陆围限、陆棚广布”的沉积格局, 深水陆棚相广泛发育, 面积为255000 km2, 平均厚度35 m。受海平面下降的影响, 从下部层序至上部层序水体变浅, 岩相从深水陆棚相黑色页岩向中-浅水陆棚相沙纹层理粉砂质页岩转变。岩相的发育受海平面升降、古陆、海底地形、物源供给等因素的影响, 岩相类型有碳质或硅质或钙质页岩、纹层状页岩、生物扰动粉砂质页岩、沙纹层理的粉砂质页岩、块状砂岩或介壳灰岩薄夹层5类。研究表明, 沉积相对富有机质页岩的形成具有内在的控制作用, 高TOC含量页岩发育于深水陆棚相、中陆棚相和潟湖相中。目前, 已有多口井在龙马溪组页岩获得工业气流, 揭示了该区良好的页岩气勘探前景;综合分析认为涪陵-赤水-仁怀、威远-长宁、鄂西-渝东为中上扬子地区下志留统页岩气勘探的主要方向和有利目标区。 相似文献
743.
The excavated height of the left bank slope of the diversion power system intake in Jinchuan hydropower station is about 16o m. The stability and safety of the slope during construction and its operation/utilization become one of the most important geological engineering problems. At the same time, it is also crucial to select a safe and economic excavation gradient for the construction. We studied the problem of how to select a safe and economic slope ratio by analyzing the geological condition of the high slope, including the lithology, slope structure, structural surface and their combinations, rock weathering and unloading, hydrology, and the natural gradient. The study results showed that the use of an excavation gradient larger than the gradient observed during site investigation and the gradient recommended in standards and field practice manuals is feasible. Then, we used the finite element method and rigid limit equilibrium method to evaluate the stability of the excavation slope under natural, rainstorm and earthquake conditions. The calculated results showed that the excavated slope only has limited failure, but its stability is greatly satisfactory. The research findings can be useful in excavation and slope stabilization projects. 相似文献
744.
????????????????SHAO????ο????????GAMIT/GLOBK??TRACK??????????????????8????????????1 Hz GPS??????д??????????????2011?????Mw9.0???????????????α??????????????????GPS???????????????????????о????н????MIZU???USUD?????????????3.11 m??0.67 m???????????λ??????????????й???????????????????????????USUD????????????????????????????????USUD???????????????RMS??1.65 cm??????0.82 cm?? 相似文献
745.
建立基于地壳不均匀的三维有限元模型,将昆仑山口西Ms8.1地震产生的长约400 km的破裂带在走向上分为16段,生成各个破裂段滑移相对于地表位移的格林函数,并以GPS观测的水平位移为约束,用阻尼最小二乘法反演破裂滑移分布,结果表明反演结果与地质考察的地表破裂数据接近.用反演结果重构的地表位移场与观测值一致,并体现了断裂... 相似文献
746.
���ں�ˮ������������������쳣�����Ϻ������� 总被引:1,自引:0,他引:1
???????????????????????????????????????????????????????????????????????????????????????????EGM96??????????ETOPO2???????????????????????Σ?????????????????????ETOPO2?????????б????侫????????ETOPO2?????????????????? 相似文献
747.
����ο����ITRF2008���й���ػ��е�Ӧ�� 总被引:1,自引:0,他引:1
???ù??????ο????ITRF2008???й???????????????????????ITRF2008??ITRF2005??CGCS2000??????ó?ITRF2008?????????????????????????????????????????????????鱾??????????????????й???й?????????????????????????????CGCS2000??仯?????????ж???????????CGCS2000??ITRF2008???????????????????????? 相似文献
748.
分析国家重力基准的现状,对国家重力基准的建立和维护提出建议. 相似文献
749.
Loss assessment and decision-making are essential for earthquake emergency rescues,and for scientific prediction of seismic damage and determination of rescue objectives.In practice,however,there exist some problems,such as basic data not being precise and rich enough and decision making not having systematic and complete criteria.This paper tries to solve these problems using the method of data indexation by constructing an index system for earthquake emergency loss assessment and decision-making. 相似文献
750.
Bin Zhao Wei Wang Shaomin Yang Maolei Peng Xuejun Qiao Ruilin Du Zhaosheng Nie 《Journal of Seismology》2012,16(2):305-313
This study estimates the far field coseismic deformation of China and its surrounding areas caused by the Mw9.0 Tohoku earthquake
of Japan using continuous GPS (cGPS) data and final orbits released by International GNSS Service (IGS). Based on these data,
we feature the coseismic offsets of several plates affected by the event. Static far field coseismic offsets greater than
2 mm are detected in a wide area of China, which extends as far as about 3,000 km off the epicenter, consisting of that of
the 2010 Maule, Chile earthquake. In northeast China, displacements up to 32.7 mm toward southeast are observed; meanwhile,
offsets in North China reach about 5–11 mm toward east. Coseismic jumps of about 2–5 mm are measured in South China toward
southeast. The southwest extrusion of the Philippine Sea plate is verified by GPS slip vectors, showing that the Philippine
Sea plate is decoupled from the Pacific plate by the earthquake. We also infer that the Amurian plate and the Okhotsk plate
couple well according to relatively continuous GPS offsets in these plates. Furthermore, the dense far field cGPS offsets
due to the Tohoku event hopefully provide opportunities to model the coseismic slip distribution. 相似文献