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   15655篇
  免费   1300篇
  国内免费   601篇
电工技术   793篇
技术理论   1篇
综合类   1047篇
化学工业   2509篇
金属工艺   786篇
机械仪表   978篇
建筑科学   1525篇
矿业工程   477篇
能源动力   462篇
轻工业   894篇
水利工程   266篇
石油天然气   967篇
武器工业   83篇
无线电   1894篇
一般工业技术   1982篇
冶金工业   733篇
原子能技术   178篇
自动化技术   1981篇
  2024年   61篇
  2023年   242篇
  2022年   427篇
  2021年   656篇
  2020年   488篇
  2019年   382篇
  2018年   421篇
  2017年   500篇
  2016年   423篇
  2015年   592篇
  2014年   730篇
  2013年   984篇
  2012年   941篇
  2011年   1009篇
  2010年   935篇
  2009年   837篇
  2008年   891篇
  2007年   794篇
  2006年   832篇
  2005年   758篇
  2004年   488篇
  2003年   450篇
  2002年   485篇
  2001年   404篇
  2000年   436篇
  1999年   447篇
  1998年   360篇
  1997年   295篇
  1996年   286篇
  1995年   240篇
  1994年   199篇
  1993年   124篇
  1992年   103篇
  1991年   105篇
  1990年   66篇
  1989年   51篇
  1988年   28篇
  1987年   25篇
  1986年   13篇
  1985年   11篇
  1984年   6篇
  1983年   11篇
  1982年   6篇
  1981年   3篇
  1980年   9篇
  1979年   1篇
  1978年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
声发射源特征识别的最新方法   总被引:8,自引:1,他引:8  
介绍多传感器数据融合、时频能量模式分析及分析理论识别声发射源特征的方法,说明基于波形分析的现代信号处理技术是揭示声发射源及信号传播规律的重要手段。  相似文献   
172.
张恭 《防腐保温技术》2006,14(3):20-21,26
对环氧粉末及3PE等防腐材料的特点进行了论述,对其存在的技术问题和人为因素进行了剖析,希望引起管道安装和管理部门对防腐技术的高度重视,保证我国的防腐市场健康向上。稳步发展。  相似文献   
173.
We present a distillation algorithm which operates on a large, unstructured, and noisy collection of internet images returned from an online object query. We introduce the notion of a distilled set, which is a clean, coherent, and structured subset of inlier images. In addition, the object of interest is properly segmented out throughout the distilled set. Our approach is unsupervised, built on a novel clustering scheme, and solves the distillation and object segmentation problems simultaneously. In essence, instead of distilling the collection of images, we distill a collection of loosely cutout foreground “shapes”, which may or may not contain the queried object. Our key observation, which motivated our clustering scheme, is that outlier shapes are expected to be random in nature, whereas, inlier shapes, which do tightly enclose the object of interest, tend to be well supported by similar shapes captured in similar views. We analyze the commonalities among candidate foreground segments, without aiming to analyze their semantics, but simply by clustering similar shapes and considering only the most significant clusters representing non‐trivial shapes. We show that when tuned conservatively, our distillation algorithm is able to extract a near perfect subset of true inliers. Furthermore, we show that our technique scales well in the sense that the precision rate remains high, as the collection grows. We demonstrate the utility of our distillation results with a number of interesting graphics applications.  相似文献   
174.
为满足高端工业检测中对检测精度和检测时间的严格要求,针对现有图像插值方法在插值速度与精度方面的矛盾,本文提出了一种分区域多方向数据融合图像插值方法。在灰度平坦区域,采用双线性插值算法进行插值。在边缘纹理区域,则选取待插值点在源图像中对应点的4×4邻域内4个插值方向上距离最近的12个像素点,基于距离平方反比计算估计值;然后结合方向灰度梯度和插值距离两个权 重因子,进行数据融合,获得最终插值。实验表明,新提出的插值方法运行速度快,并且在图像任意级别变换时都具有较高的插值精度,能够很好地保持图像的边缘纹理细节。  相似文献   
175.
针对大多数机器人最优轨迹规划控制算法成本较高的问题,提出了一种两阶段分析-进化算法,分析算法基于间接开环最优控制问题,进化算法基于遗传算法。首先,利用遗传算法产生最优控制;然后,新的次优轨迹通过最优控制生成,计算每个最优解的成本函数,并为下一个步骤选择最优解做准备;最后,遗传算法使用获得的轨迹产生新一代起始点,迭代直到实现最小成本值。算法的验证由两个仿真系统组成:具有完整约束的两关节机械手和具有非完整约束的移动机械手。运用本文算法后,第一个仿真系统的成本降低了92.3%,第二个仿真系统获得的最优成本明显低于只使用最优控制时的成本,表明其算法可应用于实际机器人轨迹规划控制系统。  相似文献   
176.
Li  Fuliang  Gong  Junfeng  Liang  Yunyi  Zhou  Jiali 《Multimedia Tools and Applications》2016,75(24):17573-17592
Multimedia Tools and Applications - Congestion prediction can support traffic departments to take effective traffic management measures, and it aids users to adopt smarter trip strategies,...  相似文献   
177.
Big data technologies and a range of Government open data initiatives provide the basis for discovering new insights into cities; how they are planned, how they managed and the day-to-day challenges they face in health, transport and changing population profiles. The Australian Urban Research Infrastructure Network (AURIN – www.aurin.org.au) project is one example of such a big data initiative that is currently running across Australia. AURIN provides a single gateway providing online (live) programmatic access to over 2000 data sets from over 70 major and typically definitive data-driven organizations across federal and State government, across industry and across academia. However whilst open (public) data is useful to bring data-driven intelligence to cities, more often than not, it is the data that is not-publicly accessible that is essential to understand city challenges and needs. Such sensitive (unit-level) data has unique requirements on access and usage to meet the privacy and confidentiality demands of the associated organizations. In this paper we highlight a novel geo-privacy supporting solution implemented as part of the AURIN project that provides seamless and secure access to individual (unit-level) data from the Department of Health in Victoria. We illustrate this solution across a range of typical city challenges in localized contexts around Melbourne. We show how unit level data can be combined with other data in a privacy-protecting manner. Unlike other secure data access and usage solutions that have been developed/deployed, the AURIN solution allows any researcher to access and use the data in a manner that meets all of the associated privacy and confidentiality concerns, without obliging them to obtain ethical approval or any other hurdles that are normally put in place on access to and use of sensitive data. This provides a paradigm shift in secure access to sensitive data with geospatial content.  相似文献   
178.
提出了一种基于灰关联混合蛙跳算法的雷达波形设计方法,以混合蛙跳算法为主体,在局部更 新算子中引入遗传算法的遗传算子,并改进原始蛙跳算法的分组方法,丰富了种群的多样性,同时引入灰关联综合评价法则对适应度函数值加以关联度分析。文中以设计具有低自相关旁瓣和互相关特性的正交多相编码为例,将该算法用于雷达波形设计中。仿真结果表明使用本文算法产生 的波形具备较好的低自相关特性和互相关特性,表明了该算法是有效和可行的。  相似文献   
179.
Quality of experience (QoE) is widely applied to reflect user’s satisfaction of the network service, which exactly conforms to the user-centric concept in 5G. In this paper, we propose a QoE-based subcarrier and power allocation algorithm for the downlink transmission of a multiuser multiservice system. For the subcarrier allocation algorithm, the rate proportional fairness factor is defined to ensure the fairness between users. Based on different QoE models of three services, i.e., file down (FD), video streaming and voice over internet protocol (VOIP), a multi-objective optimization method is exploited to allocate the power resource by minimizing the total power consumption and maximizing the mean opinion score (MOS) value of users simultaneously. Simulation results indicate that the proposed algorithm has less power consumption and higher QoE performance than the traditional proportional fairness (PF) algorithm. In addition, the proposed algorithm can achieve nearly the same fairness performance as the PF algorithm. Moreover, when the number of subcarriers becomes larger, the power assumption will be less but with little influence on both the QoE and fairness performances.  相似文献   
180.
Dear editor,At Asiacrypt 2011,Bogdanov et al.[1]formally defined the biclique cryptanalysis method and proposed the first key recovery attack on full-round AES faster than exhaustible search in single-key model.The basic idea underlying the biclique cryptanalysis is to determine two independent(or interleaving)differential paths in the forward and the backward direction to construct a biclique for a  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