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   41992篇
  免费   5145篇
  国内免费   3562篇
电工技术   3708篇
技术理论   10篇
综合类   5806篇
化学工业   819篇
金属工艺   477篇
机械仪表   2089篇
建筑科学   2768篇
矿业工程   1399篇
能源动力   401篇
轻工业   610篇
水利工程   1170篇
石油天然气   983篇
武器工业   926篇
无线电   6684篇
一般工业技术   2151篇
冶金工业   1606篇
原子能技术   116篇
自动化技术   18976篇
  2024年   71篇
  2023年   467篇
  2022年   946篇
  2021年   1175篇
  2020年   1297篇
  2019年   957篇
  2018年   874篇
  2017年   1175篇
  2016年   1435篇
  2015年   1606篇
  2014年   3006篇
  2013年   2712篇
  2012年   3364篇
  2011年   3392篇
  2010年   2599篇
  2009年   2838篇
  2008年   3061篇
  2007年   3277篇
  2006年   3027篇
  2005年   2637篇
  2004年   2310篇
  2003年   2020篇
  2002年   1450篇
  2001年   1191篇
  2000年   939篇
  1999年   615篇
  1998年   432篇
  1997年   343篇
  1996年   282篇
  1995年   218篇
  1994年   200篇
  1993年   142篇
  1992年   102篇
  1991年   77篇
  1990年   53篇
  1989年   60篇
  1988年   44篇
  1987年   29篇
  1986年   24篇
  1985年   27篇
  1984年   36篇
  1983年   31篇
  1982年   18篇
  1981年   15篇
  1980年   17篇
  1979年   15篇
  1977年   8篇
  1965年   10篇
  1964年   11篇
  1961年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The construction of specialty groups in higher vocational colleges is in full swing. However, due to the cognitive bias and the lack of construction paradigm for reference, the construction of specialty groups is still in the period of "crossing the river by feeling the stones" with different opinions. There are some problems in the construction of specialty groups, such as unclear under- standing of the concept of specialty groups, unreasonable logic of groups, unclear construction of groups, and nonstandard manage- ment of groups. This paper describes the specific content of the construction of modern information technology specialty group based on the Sydney Agreement, hoping to form a reference paradigm for the construction of specialty group of similar colleges and universities.  相似文献   
12.
Lack of constraint-free crane path planning is one of the critical concerns in the dynamic on-site assembly process of prefabrication housing production (PHP). For decades, researchers and practitioners have endeavored to improve both the efficiency and safety of crane path planning from either static environment or re-planning the path when colliding with constraints or periodically updating the path in the dynamic environment. However, there is a lack of approach related to the in-depth exploration of the nature of dynamic constraints so as to assist the crane operators in making adaptive path re-planning decisions by categorizing and prioritizing constraints. To address this issue, this study develops the smart work packaging (SWP)-enabled constraints optimization service. This service embraces the core characteristics of SWP, including adaptivity, sociability, and autonomy to achieve autonomous initial path planning, networked constraints classification, and adaptive decisions on path re-planning. This service is simulated and verified in the BIM environment, and it is found that SWP-enabled constraints optimization service can generate the constraint-free path when it is necessary.  相似文献   
13.
Search results of spatio-temporal data are often displayed on a map, but when the number of matching search results is large, it can be time-consuming to individually examine all results, even when using methods such as filtered search to narrow the content focus. This suggests the need to aggregate results via a clustering method. However, standard unsupervised clustering algorithms like K-means (i) ignore relevance scores that can help with the extraction of highly relevant clusters, and (ii) do not necessarily optimize search results for purposes of visual presentation. In this article, we address both deficiencies by framing the clustering problem for search-driven user interfaces in a novel optimization framework that (i) aims to maximize the relevance of aggregated content according to cluster-based extensions of standard information retrieval metrics and (ii) defines clusters via constraints that naturally reflect interface-driven desiderata of spatial, temporal, and keyword coherence that do not require complex ad-hoc distance metric specifications as in K-means. After comparatively benchmarking algorithmic variants of our proposed approach – RadiCAL – in offline experiments, we undertake a user study with 24 subjects to evaluate whether RadiCAL improves human performance on visual search tasks in comparison to K-means clustering and a filtered search baseline. Our results show that (a) our binary partitioning search (BPS) variant of RadiCAL is fast, near-optimal, and extracts higher-relevance clusters than K-means, and (b) clusters optimized via RadiCAL result in faster search task completion with higher accuracy while requiring a minimum workload leading to high effectiveness, efficiency, and user satisfaction among alternatives.  相似文献   
14.
本文建立了PC结构施工全过程的BIM模型及有限元分析模型,对施工过程进行数值模拟与动态、静态监测,对装配式结构进行了结构性能评价,为结构可视化施工监测提供了技术支持。  相似文献   
15.
In this paper, we present a performance analysis of large-scale multi-input multi-output (MIMO) systems for wireless backhaul networks. We focus on fully connected N nodes in a wireless meshed and multi-hop network topology. We also consider a large number of antennas at both the receiver and transmitter. We investigate the transmission schemes to support fully connected N nodes for half-duplex and full-duplex transmission, analyze the achievable ergodic sum rate among N nodes, and propose a closed-form expression of the achievable ergodic sum rate for each scheme. Furthermore, we present numerical evaluation results and compare the resuts with closed-form expressions.  相似文献   
16.
邹志云  朱文超  刘英莉  孟磊  郭宁  于蒙 《化工进展》2020,39(z2):269-275
针对采取小批量间歇性批次生产方式、工艺介质腐蚀性强、危险性大的小型特种精细化工生产工艺研究试验过程自动化、信息化程度不高,导致工艺研究试验中获取数据较少、过程机理研究不够透彻、人工操作多、安全风险高、研究试验消耗大及效率不高等问题,综述了期待通过智能控制、在线分析、模拟仿真和虚拟制造、工况监测及预测性维护以及信息管理和生产调度等关键技术的研究和应用,提高小型特种精细化工生产工艺过程的自动化和信息化程度,实现小型特种精细化工生产工艺过程的数字化、虚拟化和智能化,降低生产安全风险和试验消耗,提高小型特种精细化工生产工艺研究试验的成功率和效率,达到小型特种精细化工生产工艺过程的数字化设计和精准生产的目标。  相似文献   
17.
文章首先总结了电力企业信息管理系统的现状,提出了多源信息管理系统融合集成的邦联、子集和完全融合3种方式,分析了3种方式的优缺点,以建设企业"互联网搜索"型数字引擎为目标,提出了融合基于本体的图数据库建模,多维关联与路径因果分析,和人机共生互动可视化决策于一体的企业信息管理系统技术发展趋势;在系统分析目前正在快速发展的图数据库技术与传统关系数据库之间的本质区别基础上,总结原创的电力图计算平台技术的特点;在此基础上讨论"电网一张图"在建设能源互联网时空信息管理平台数据关联索引图中的核心作用,提出了支持能源互联网建设的"电网一张图"时空信息管理系统的技术架构与特点,最后总结"电网一张图"时空信息管理系统在提高电网安全运行水平、提升客户服务水平、增强清洁能源消纳水平、改善经营绩效水平、以及为综合能源服务和建设能源生态等提供数据服务方面的广阔应用场景。  相似文献   
18.
何桥  许金 《中州煤炭》2020,(1):56-59
以煤矿安全隐患排查治理风险为研究对象,分析隐患排查闭环管理全过程,并基于此建立了隐患排查治理能力纵向评估指标体系,融合熵值法和集对分析理论,建立了煤矿安全隐患排查治理风险纵向评估模型,为企业更好地了解自身隐患排查治理能力及变化发展趋势提供参考,最后进行了实例分析。  相似文献   
19.
In the task of skeleton-based action recognition, CNN-based methods represent the skeleton data as a pseudo image for processing. However, it still remains as a critical issue of how to construct the pseudo image to model the spatial dependencies of the skeletal data. To address this issue, we propose a novel convolutional neural network with adaptive inferential framework (AIF-CNN) to exploit the dependencies among the skeleton joints. We particularly investigate several initialization strategies to make the AIF effective with each strategy introducing the different prior knowledge. Extensive experiments on the dataset of NTU RGB+D and Kinetics-Skeleton demonstrate that the performance is improved significantly by integrating the different prior information. The source code is available at: https://github.com/hhe-distance/AIF-CNN.  相似文献   
20.
We consider ex post demand information sharing in a two-echelon supply chain in which two suppliers sell differentiated products through a common retailer. We model three scenarios of information sharing to characterise the conditions under which information sharing may benefit or hurt different players: (1) no supplier is informed; (2) only one supplier is informed; and (3) both suppliers are informed. We find that the retailer may voluntarily share the low demand information when the product differentiation and demand magnitude satisfy certain conditions. In contrast, the retailer has no incentive to share the high demand information, even though this information benefits the suppliers. To achieve information sharing, we propose a side payment mechanism, which allows benefitted players to subsidise hurtful players. Finally, we extend our model by considering a situation where the suppliers have limited capacity and may invest to ramp up production capacity to satisfy a high demand.  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