首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   111篇
  免费   2篇
  国内免费   2篇
综合类   2篇
化学工业   10篇
建筑科学   10篇
矿业工程   9篇
能源动力   1篇
石油天然气   5篇
一般工业技术   4篇
冶金工业   65篇
原子能技术   4篇
自动化技术   5篇
  2019年   1篇
  2016年   1篇
  2015年   2篇
  2014年   1篇
  2013年   2篇
  2012年   1篇
  2011年   7篇
  2010年   9篇
  2009年   16篇
  2008年   11篇
  2007年   6篇
  2006年   16篇
  2005年   9篇
  2004年   12篇
  2003年   5篇
  2002年   5篇
  2001年   3篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1991年   3篇
  1988年   1篇
排序方式: 共有115条查询结果,搜索用时 15 毫秒
101.
A significant number of petroleum reservoirs and almost all geothermal reservoirs are characterized by high in situ stress and fractures, and fractures act as major flow paths for fluids. An integrated tensor model is proposed to solve three tasks: characterization of a heterogeneous fracture network, simulation of fluid flow through a complex system for estimation of the grid-based permeability tensor, and unsteady-state fluid flow simulation for estimation of production and pressure losses. Deformation of the matrix and fractures are solved separately and used to compute their dynamic porosity and permeability. Finite-element methods and boundary element methods are used for numerical modeling. The results of this study show that the proposed model can overcome problems requiring excessive computational resources, flow interactions between the matrix and fracture, and the effect of matrix deformation on fluid flow. Results also show that the integrated tensor model serves as an efficient tool for predicting the effect of stress on fracture deformation and consequent productivity and/or injectivity of naturally fractured reservoirs.  相似文献   
102.
鄂尔多斯盆地吴定地区烃源岩的油源对比   总被引:2,自引:0,他引:2  
为了研究鄂尔多斯盆地吴定地区烃源岩油源对比,通过萜烷、甾烷生物标志化合物特征,厘定油源关系。原油和源岩的分析表明,长8储集层原油与长7烃源岩有密切的亲缘关系,而与长9烃源岩可比性差。因此,长8的原油来源于长7烃源岩。  相似文献   
103.
A variety of methods are utilized to reinvestigate the physical relationship between the seismic response of Treasure Island (TI) and Yerba Buena Island (YBI) in California. These islands are a soil (TI) and rock (YBI) site pair separated by 2 km. The site pair has been used previously by researchers to identify soil response to earthquake shaking. Linear regime ground motions (MW4.0–MW4.6 and PGA: 0.014–0.017 g) recorded in the TI vertical array indicate a coherent wavefield in the sediments and an incoherence between the rock and sediments. Our analyses show that the greatest change in the wavefield occurred between the rock and soil layers, corresponding to a significant impedance contrast. The waveforms change very little as they propagate through the sediments, indicating that the site response is a cumulative effect of the entire soil structure and not a result of wave propagation within individual soil layers. In order to highlight the complexity of the site response, correlation analysis was used to demonstrate that the rock and soil ground motions were not highly coherent between the two sites. YBI was, therefore, shown to be an inappropriate reference site for TI. One-dimensional (1D) vertical wave propagation and inverse techniques were used to differentiate between 1D site response and more complex site behavior. Both 1D methods (vertical wave propagation and inverse transfer functions) proved incapable of capturing the site response at TI beyond the initial four seconds of motion. Finite difference waveform modeling, based on a two-dimensional velocity structure of the northern San Francisco Bay was needed to explain the linear site response at TI as horizontally propagating surface waves trapped in the bay sediments. A simplified velocity structure for the San Francisco Bay including a single 100 m basin layer (constant shear-wave velocity of 400 m/s) over a 1.5 km/s layer of Franciscan bedrock was able to trap energy in the basin and produce surface waveform ringing similar to that observed in the TI data. Due to surface waves propagating in the San Francisco Bay sediments, any 1D model will not fully characterize site response at TI. All 1D models will fail to produce the late arriving energy observed in the ground motions.  相似文献   
104.
塔里木盆地属缝洞型碳酸盐岩储层,在试油时易喷易漏、井控安全隐患突出,为了解决此类问题,研发了以HP-1AH封隔器为核心组件的测试-改造-封堵-回采一体化工艺管柱,解决了该类储层试油作业易漏易喷井控风险的技术难题;同时减少了多次压井作业对储层造成的二次污染,缩短了施工作业周期,节约了成本,现场应用效果良好。  相似文献   
105.
An experimental air convection embankment (ACE) was constructed in Beiluhe on the Qinghai-Tibet Plateau during 2001–2003, using coarse (5–8 and 40–50 cm), poorly graded crushed rock fill material on the slope of embankment with thick ground ice permafrost foundation, which should be called the air convection embankment with crushed rock slope protection (ACE–CRSP). The highly permeable ACE–CRSP installation was designed to test the cooling effectiveness of ACE–CRSP concept in an actual railway project. Ground temperature data were collected from test sections on the railway with thermistor sensor strings. The results showed that the mean ground temperature under the layer of the crushed rock with coarse particle diameter of 40–50 cm was lower than that under one with finer particle diameter of 5–8 cm, and the fluctuating range of temperature under the former was bigger than that under the latter. It was obvious that the maximum thaw depth was raised under the layer of crushed rock with coarse particle diameter of 40–50 cm, which resulted from the stronger cooling effectiveness of air convection during the winter. The amount of heat exchange also showed that the absorbed cooling energy of the foundation, under the layer of the crushed rock with coarse diameter, was larger than that with finer diameter.So, we believe that the cooling effectiveness of the crushed rock layer with coarse diameter was stronger than that one with finer diameter.  相似文献   
106.
Evaporative losses from the surface of barren waste rock piles in arid environments occur as a result of water vapor diffusion. Water vapor diffusion is accompanied by adsorption of water vapor. A review of the literature found that adsorption of water vapor is commonly described as a sigmoidal function of suction with a predominant linear portion when plotted against the log of suction. Laboratory column tests were conducted with glass beads and waste rock to study water vapor diffusion. A monitoring system was developed for measuring relative humidity and temperature through the column. Water vapor fluxes and relative humidity profiles through the column were measured under steady-state conditions to establish the method of estimating the water vapor diffusion coefficient. Transient water vapor fluxes and relative humidity profiles were measured and a numerical model was developed to simulate the laboratory observations. The numerical model demonstrated the importance of water sorption in controlling the transient water vapor flux. Sorption described as a log–linear function of suction gave reasonable results for the numerical modeling of the glass beads and waste rock.  相似文献   
107.
In this Technical Note, the adaptive block element method of rock masses is formulated, in which the elastoplastic characteristics of both rock blocks and discontinuities are taken into account. The concept of an overlay element is illustrated first; then the displacement fields of rock blocks are expressed as functions of so-called general degree of freedoms using the shape functions of the hierarchical finite element method; the governing equations of the rock block system are deduced on the basis of the virtual work principle; and the p-version adaptive algorithm based on the energy norm error estimation of each block element is proposed. The method is applied to the deformation and stability study of a gravity dam, and the parallel laboratory physical test is used to check the validity and ability of the method.  相似文献   
108.
Compaction bands, a form of localized deformation found in field and laboratory specimens of high porosity rock, consist of planar zones of pure compressional deformation that form perpendicular to maximum compression. Experimentalists report compaction bands and/or shear bands (angled to maximum compression) in high porosity sandstone during a transitional loading regime with multiple active deformation mechanisms. Conditions for localized deformation are determined using a two-yield surface constitutive model and bifurcation theory. The shear yield surface corresponds to a dilatant, frictional mechanism while the cap corresponds to a compactant mechanism. Unlike a single yield surface model, the two-yield surface model predicts both experimentally observed band types for reported values of key material parameters. Observed and predicted shear band angles generally agree. Theory suggests that shear band formation may coincide with activation of the shear yield surface by a previously active cap. If the bulk hardening modulus, k, equals zero (corresponding to localization on the peak or plateau of the mean stress–volume strain curve) compaction band conditions are more favorable than for small positive values of k.  相似文献   
109.
通过充矸留巷生产工艺的探索实现了工作面无煤柱开采,在井下工业性试验的基础上,确立了无煤柱开采的配套工艺方案,闯出了一条节能减排的新思路。  相似文献   
110.
Block ramps are a short length of a steep channel armored with rocks, which produce high dissipation of energy. This technical note presents the results of experiments performed on a ramp having a staggered arrangement of hemispherical boulders with base material on its bed. Compared to row and random arrangements of boulders, a staggered arrangement produces more dissipation of energy. Relative energy loss in the ramp depends not only on the discharge but also on boulder concentration and their sizes. A relationship is proposed that satisfactorily determines the dissipation of energy on the ramp with base material and boulders placed with a staggered arrangement.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号