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排序方式: 共有492条查询结果,搜索用时 16 毫秒
91.
92.
为研究适用于洞庭湖区二元结构堤基的减压井结构型式,采用室内试验对比分析了土工织物包扎塑料花管式、钢管式、砂滤体式及无砂混凝土式井管的排水减压效果,并结合洞庭湖区何家堤减压井试验工程研究了合理的滤层结构。试验表明,塑料盲沟和毛细板减压井是适合洞庭湖区二元堤基的两种减压井结构型式。 相似文献
93.
珠江三角洲的软土分布广泛,水利建设中正在遇到大量在软土地基上的堤围加固,穿堤涵闸的建设问题,其中最主要的技术难题是软基处理的问题。本文主要是针对目前建设中遇到的软土地基承载力的合理确定问题及涵闸地基处理、软土地基的变形问题、填土速率的控制问题、旧堤加固及软土参数取值问题、侧向土压力问题、复合地基的应用问题、软土施工顺序的影响等技术问题进行探讨,因为这些问题影响到工程的质量和安全,是目前工程建设中急需解决的问题。 相似文献
94.
T. -T. Yu J. Fernndez C. -L. Tseng M. J. Sevilla V. Araa 《Journal of Volcanology and Geothermal Research》2000,103(1-4)
A 17-benchmark geodetic network in the volcanic area of the Teide Caldera, Canary Islands has been utilised several times since 1982 to detect crustal movements associated with volcanic activity within the network, as well as a procedure for solving configuration problems. The network is located on the mid-western side of the Caldera, where there are two different morphological zones that both have benchmarks. The authors performed a sensitivity test of this geodetic network for volcano monitoring purposes. To do so, we use a deformation model to calculate surface displacement caused by a dike intrusion in a homogenous half space. The depth and location of dike are changed to study the variation of the effects produced (displacements). The size and location of the intruded dike are found to play a major role in determining both the displacement pattern and magnitude. When the dike is close to the surface, there is an inversion of the surface displacement pattern and very large surface displacement at certain benchmarks. Such phenomena can serve as precursors of such dike eruptions. Our study show a clear need to extend the existing geodetic network to cover the full island for volcano monitoring purposes. 相似文献
95.
辉长岩脆-塑性转化及其影响因素的高温高压实验研究 总被引:9,自引:1,他引:8
本文利用高温高压多功能三轴实验装置,以NaCl为固体围压传压介质,在围压为450MPa~800MPa,温度区间为600℃~1150℃和应变速率为1×10-4~3.125×10-6/s条件下,对攀枝花辉长岩进行了流变学实验研究。实验结果表明,辉长岩围压在450MPa~800MPa条件下,温度在600℃时为脆性变形,700℃~850℃时为半塑性流动,含微破裂,大于900℃时为塑性流动。辉长岩的脆-塑性转化温度为700℃~900℃,主要影响因素为温度、围压和应变速率,同时存在双相流变学问题。 相似文献
96.
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98.
综合论述了潟湖潮汐通道口门之流速、断面面积、通道长度、延时角和饱满系数之间的关系,以及沿岸漂沙对口门的影响。对不同类型的潟湖潮汐通道,提出了中潮位射流导流堤、口门复式断面和通道分汊等治理方法及其通道口门相关尺度的具体计算。 相似文献
99.
Currently, numerical studies at the real scale of an entire engineering structure considering internal erosion are still rare. This paper presents a three-dimensional (3D) numerical simulation of the effects of internal erosion within a linear dike located on a foundation. A two-dimensional (2D) finite element code has been extended to 3D in order to analyze the impact of internal erosion under more realistic hydromechanical conditions. The saturated soil has been considered as a mixture of four interacting constituents: soil skeleton, erodible fines, fluidized fine particles, and fluid. The detachment and transport of the fine particles have been modeled with a mass exchange model between the solid and the fluid phases. An elastoplastic constitutive model for sand-silt mixtures has been developed to monitor the effect of the evolution of both the porosity and the fines content induced by internal erosion upon the behavior of the soil skeleton. An unsaturated flow condition has been implemented into this coupled hydromechanical model to describe more accurately the seepage within the dike and the foundation. A stabilized finite element method was used to eliminate spurious numerical oscillations in solving the convection-dominated transport of fluidized particles. This numerical tool was then applied to a specific dike-on-foundation case subjected to internal erosion induced by a leakage located at the bottom of the foundation. Different failure modes were observed and analyzed for different boundary conditions, including the significant influence of the leakage cavity size and the elevation of the water level at the upstream and downstream sides of the dike. 相似文献
100.
Lycian ophiolites located in the Western Taurides, are cut at all structural levels by dolerite and gabbro dikes. The dolerite
dikes from this area are both pristine and metamorphosed. The non-metamorphosed dikes are observed both in the peridotites
and in the metamorphic sole rocks. Accordingly, the non-metamorphosed dikes cutting the metamorphic sole were generated after
cooling of the metamorphic sole rocks. The metamorphosed dolerite dikes are only observed in the peridotites. The physical
conditions and timing of the metamorphism for the metamorphosed dolerite dikes are similar to those of the metamorphic sole
rocks of the Lycian ophiolites suggesting that the metamorphosed dolerite dikes were metamorphosed together with the metamorphic
sole rocks. Therefore, the dike injections in the western part of the Tauride Belt Ophiolites occurred before and after the
generation of the metamorphic sole rocks. All metamorphosed and non-metamorphosed dikes are considered to have the same origin
and all of them are subduction-related as inferred from whole-rock geochemistry and lead isotopes. Lead isotope compositions
of whole rocks of both dike groups cluster in a narrow field in conventional Pb isotope diagrams (206Pb/204Pb = 18.40–18.64; 207Pb/204Pb = 15.56–15.58; 208Pb/204Pb = 38.23–38.56) indicating a derivation from an isotopically homogeneous source. On the 207Pb/204Pb versus 206Pb/204Pb diagram, isotope compositions of the dikes plot slightly below the orogen curve suggesting contributions from mantle reservoir
enriched by subducted oceanic lithosphere. Such a signature is typical of island arc magmatic rocks and supports the formation
of the investigated rocks in a subduction-related environment. 相似文献