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   283篇
  免费   21篇
  国内免费   7篇
电工技术   3篇
综合类   22篇
化学工业   54篇
金属工艺   16篇
机械仪表   35篇
建筑科学   5篇
矿业工程   2篇
能源动力   2篇
轻工业   4篇
水利工程   2篇
石油天然气   13篇
武器工业   1篇
无线电   12篇
一般工业技术   18篇
冶金工业   105篇
自动化技术   17篇
  2023年   2篇
  2022年   1篇
  2021年   7篇
  2020年   4篇
  2019年   9篇
  2018年   3篇
  2017年   4篇
  2016年   5篇
  2015年   15篇
  2014年   12篇
  2013年   10篇
  2012年   6篇
  2011年   23篇
  2010年   21篇
  2009年   15篇
  2008年   19篇
  2007年   26篇
  2006年   28篇
  2005年   19篇
  2004年   16篇
  2003年   22篇
  2002年   13篇
  2001年   10篇
  2000年   4篇
  1998年   5篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1987年   1篇
  1979年   1篇
  1977年   1篇
排序方式: 共有311条查询结果,搜索用时 0 毫秒
111.
In this research, the overall heat transfer coefficient of Al2O3/water–mono ethylene glycol (MEG) nanofluids is investigated experimentally in a car radiator under laminar flow conditions. The experimental rig developed is similar to the automotive cooling system. The stable nanofluid used is prepared by a two‐step method. Ultrasonication is done for proper dispersion of 20 nm Al2O3 nanoparticle in carrier fluid water and MEG mixture with 50:50 proportions by volume. The experimental study showed that use of a nanofluid enhances the overall heat transfer coefficient as compared to the base fluid. In this study as the nanoparticle volume fraction increases from 0% to 0.8%, the overall heat transfer coefficient also increases. It was observed that as the nanofluid inlet temperature increased from 65 °C to 85 °C, the overall heat transfer coefficient decreased. It was found that using a 0.2% volume fraction Al2O3/water–MEG nanofluid can enable a 36.69 % reduction in surface area of the radiator.  相似文献   
112.
龙门山冲断带前缘地区侏罗系出露与油气分布关系   总被引:1,自引:0,他引:1  
龙门山冲断带前缘地区目前已发现的油气田或舍油气构造主要分布在马角坝-通济场-双石断裂以东,统计分析结果表明52%分布在马角坝-通济场-双石断裂与广元-关口-大邑断裂之间(即前缘褶皱冲断带),其地表出露为侏罗系。其余则主要分布在广元-关口-大邑断裂以东的前陆坳陷带,地表为白垩系或第四系覆盖,认为侏罗系出露地区具有较好的油气勘探前景。通过研究区典型地震剖面解释,从构造变形角度解释这种油气分布特征的成因。  相似文献   
113.
深水沉积是世界油气增储上产的重要领域之一。目前,国外学者针对深水沉积的构型模式开展了大量研究,但研究对象多为浊积水道,而对于浊积朵叶的关注则甚少。为此,以西非尼日尔三角洲盆地某深水区块地下储层和中国甘南西秦岭地区某深水露头作为原型,采用地震相分析、地震沿层切片、露头观察描述等多种手段相结合的方法,分级次开展了浊积朵叶的构型模式研究。研究表明,浊积朵叶的构型单元可划分为7级,其中3~5构型单元分别为:单一朵叶、复合朵叶和朵叶体系。朵叶体系由多个复合朵叶叠置而成。复合朵叶内部发育树枝状的下切水道,底部发育块体搬运沉积,其常常对下伏地层有明显侵蚀。单一朵叶由受平行、亚平行界面约束的多期板状砂岩垂向加积而成,依据其内部沉积特征的差异,可进一步分为近朵叶端、中朵叶端和远朵叶端3部分。通过研究不仅可以深化浊积朵叶的地质理论,而且可以有效降低此类油气田的勘探开发风险,具有重要的实际意义。  相似文献   
114.
Patients with focal frontal or nonfrontal lesions were compared with control participants on 4 reaction time (RT) tasks varying in levels of complexity based on a feature-integration model of detection. Superior medial lesions affected simple RT speed. Increasing the demands of feature detection did not differentially affect speed of correct responses among the groups. Frontal structures appear to play little role in correct integration of features during detection. The analysis of error types within the complex task revealed a frontal lobe hemispheric distinction between sensitivity and bias: right dorsolateral-decreased sensitivity; left dorsolateral-altered response bias. The frontal lobes, particularly right dorsolateral, were required to inhibit an incorrect response. There are at least 3 functionally and anatomically separable anterior attentional processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
115.
We address the problem of automatic partitioning of unstructured finite element meshes in the context of parallel numerical algorithms based on domain decomposition. A two-step approach is proposed, which combines a direct partitioning scheme with a non-deterministic procedure of combinatorial optimization. In contrast with previously published experiments with non-deterministic heuristics, the optimization step is shown to produce high-quality decompositions at a reasonable compute cost. We also show that the optimization approach can accommodate complex topological constraints and minimization objectives. This is illustrated by considering the particular case of topologically one-dimensional partitions, as well as load balancing of frontal subdomain solvers. Finally, the optimization procedure produces, in most cases, decompositions endowed with geometrically smooth interfaces. This contrasts with available partitioning schemes, and is crucial to some modern numerical techniques based on domain decomposition and a Lagrange multiplier treatment of the interface conditions.  相似文献   
116.
Although several studies have examined anterior asymmetric brain electrical activity and cortisol in infants, children, and adults, the direct association between asymmetry and cortisol has not systematically been reported. In nonhuman primates, greater relative right anterior activation has been associated with higher cortisol levels. The current study examines the relation between frontal electroencephalographic (EEG) asymmetry and cortisol (basal and reactive) and withdrawal-related behaviors (fear and sadness) in 6-month-old infants. As predicted, the authors found that higher basal and reactive cortisol levels were associated with extreme right EEG asymmetry. EEG during the withdrawal-negative affect task was associated with fear and sadness behaviors. Results are interpreted in the context of the previous primate work, and some putative mechanisms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
117.
提出了将有限元、组合条元与映射无穷元联合应用求解无限域问题的思想 .首先介绍 6种映射无穷元的位移模式和坐标映射关系 ;然后基于联合应用组合条元的要求 ,提出了一种新型单元—组合映射无穷元 ,并建立了相应的公式 ;编制了计算程序 ,经过算例分析证明了有限元、组合条元与映射无穷元联合应用方法的正确性和有效性  相似文献   
118.
分析了波前法在组合结构有限元分析中的应用方法,并编写了相应的有限元程序。  相似文献   
119.
[Correction Notice: An erratum for this article was reported in Vol 4(1) of Journal of Neuroscience, Psychology, and Economics (see record 2011-01447-001). Figures 8 and 9 were printed with errors. Corrected versions of these figures are presented in the erratum.] [Correction Notice: An erratum for this article was reported in Journal of Neuroscience, Psychology, and Economics (see record 2011-01447-001). Figures 8 and 9 were printed with errors.] Researchers have recently begun to explore the physiological factors influencing consumer preferences for product brands. The medial frontal cortex (MFC) is critically involved in both emotion processing and prepurchase product assessment. However, analyses of MFC activation with near-infrared ray (NIR) imaging are rarely compared between brand-loyal customers and switchers (brand nonloyals) to investigate the long-term effects of luxury products. Subjects, classified as loyals or switchers, performed a 2-session task: (a) evaluate their product preferences while undergoing NIR imaging, and (b) rate products on several dimensions (e.g., willingness to purchase). Variables examined were brand and attractiveness. Results for preference rating and reaction time indicate that loyals are more sensitive than switchers in differentiating between luxury and generic and between attractive and unattractive products. Additionally, MFC activation reflects product attractiveness. The interaction between brand and attractiveness dominated the preferences of most subjects. The link between MFC activation and the preference for products seems not only related to luxury brands but also rooted in product attractiveness. Consequently, this preliminary investigation presents a novel approach for branding research based on measuring brain responses. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
120.
为了主动调整摄像机的位置姿态以在物方空间降低由人脸旋转带来的影响,提出人脸-摄像机主动位姿协同方法. 利用工业摄像机与同步带类运动控制器搭建位姿协同环境,根据单像空间后方交会方法求解运动人脸姿态角和相对位置,计算人脸、摄像机和运动控制器各坐标系之间的映射关系,摄像机运动由相邻采样时刻摄像机相对位置和人脸姿态角计算得出的摄像机协同位姿控制,主动、实时地获取人脸正视图像. 实验表明,运动轴上的摄像机点位误差小于10 mm,取得的人脸正视图像提高了人脸纠正的精准度与鲁棒性.  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