全文获取类型
收费全文 | 13237篇 |
免费 | 1121篇 |
国内免费 | 731篇 |
专业分类
电工技术 | 594篇 |
技术理论 | 3篇 |
综合类 | 2217篇 |
化学工业 | 1596篇 |
金属工艺 | 439篇 |
机械仪表 | 475篇 |
建筑科学 | 1462篇 |
矿业工程 | 1218篇 |
能源动力 | 489篇 |
轻工业 | 820篇 |
水利工程 | 716篇 |
石油天然气 | 709篇 |
武器工业 | 329篇 |
无线电 | 637篇 |
一般工业技术 | 945篇 |
冶金工业 | 753篇 |
原子能技术 | 80篇 |
自动化技术 | 1607篇 |
出版年
2024年 | 34篇 |
2023年 | 110篇 |
2022年 | 316篇 |
2021年 | 360篇 |
2020年 | 406篇 |
2019年 | 319篇 |
2018年 | 248篇 |
2017年 | 334篇 |
2016年 | 406篇 |
2015年 | 397篇 |
2014年 | 895篇 |
2013年 | 752篇 |
2012年 | 962篇 |
2011年 | 975篇 |
2010年 | 780篇 |
2009年 | 883篇 |
2008年 | 739篇 |
2007年 | 878篇 |
2006年 | 819篇 |
2005年 | 710篇 |
2004年 | 644篇 |
2003年 | 543篇 |
2002年 | 465篇 |
2001年 | 377篇 |
2000年 | 360篇 |
1999年 | 283篇 |
1998年 | 191篇 |
1997年 | 173篇 |
1996年 | 143篇 |
1995年 | 125篇 |
1994年 | 88篇 |
1993年 | 61篇 |
1992年 | 54篇 |
1991年 | 33篇 |
1990年 | 37篇 |
1989年 | 29篇 |
1988年 | 23篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1984年 | 7篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1966年 | 6篇 |
1964年 | 8篇 |
1963年 | 6篇 |
1961年 | 7篇 |
1959年 | 5篇 |
1958年 | 5篇 |
1957年 | 12篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
大同市节水型社会建设的探讨 总被引:1,自引:0,他引:1
大同市是全国108个比较严重缺水城市之一,人均水资源量不足全国的1/10(全国人均水资源量2231m^3),稍超过全省的1/2(全省人均水资源量388m^3),市中心城区工农业及城市生活用水近20年来靠超采地下水来支撑。文中就大同市水资源供需不平衡的现状,提出大同市节水型社会建设的必要性,及今后水资源开源和节流的措施。 相似文献
12.
洪华芬 《中国计量学院学报》2003,14(4):328-330
从师德和法律这两个不同的概念入手,剖析现实教学中存在的种种负面行为,这些行为中有违反 道德和违反法律之分.在加强师德教育的同时,应该加强法治教育,应该知道遵守法律是每个公民应尽的义 务,你首先是个好公民,你才可能是个好教师.从这个意义上说,加强师德教育,守法是基础. 相似文献
13.
水锤涌浪联合试验的变态模型相似律 总被引:1,自引:0,他引:1
该文详细推导了在同一个物理模型中同时模拟调压室涌浪和压力钢管中的水锤时应满足的变态模型相似律,结果应用于电站模型试验中。 相似文献
14.
15.
Automatic fog detection and estimation of visibility distance through use of an onboard camera 总被引:2,自引:0,他引:2
Nicolas Hautiére Jean-Philippe Tarel Jean Lavenant Didier Aubert 《Machine Vision and Applications》2006,17(1):8-20
In this paper, we will present a technique for measuring visibility distances under foggy weather conditions using a camera mounted onboard a moving vehicle. Our research has focused in particular on the problem of detecting daytime fog and estimating visibility distances; thanks to these efforts, an original method has been developed, tested and patented. The approach consists of dynamically implementing Koschmieder's law. Our method enables computing the meteorological visibility distance, a measure defined by the International Commission on Illumination (CIE) as the distance beyond which a black object of an appropriate dimension is perceived with a contrast of less than 5%. Our proposed solution is an original one, featuring the advantage of utilizing a single camera and necessitating the presence of just the road and sky in the scene. As opposed to other methods that require the explicit extraction of the road, this method offers fewer constraints by virtue of being applicable with no more than the extraction of a homogeneous surface containing a portion of the road and sky within the image. This image preprocessing also serves to identify the level of compatibility of the processed image with the set of Koschmieder's model hypotheses.
Nicolas Hautiére graduated from the École Nationale des Travaux Publics de l'État, France (2002). He received his M.S. and Ph.D. degree in computer vision, respectively, in 2002 and 2005 from Saint-Étienne University (France). From 2002, he is a researcher in the Laboratoire Central des Ponts et Chaussées (LCPC), Paris, France. His research interests include trafic engineering, computer vision, and pattern recognition.
Jean-Philippe Tarel graduated from the École Nationale des Ponts et Chaussées, Paris, France (1991). He received his Ph.D. degree in Applied Mathematics from Paris IX-Dauphine University in 1996 and he was with the Institut National de Recherche en Informatique et Automatique (INRIA) from 1991 to 1996. From 1997 to 1998, he was a research associate at Brown University, USA. From 1999, he is a researcher in the Laboratoire Central des Ponts et Chaussées (LCPC), Paris, France, and from 2001 to 2003 in the INRIA. His research interests include computer vision, pattern recognition, and shape modeling.
Jean Lavenant graduated from the École Nationale des Travaux Publics de l'État, Lyon, France (2001). He received the M.S. degree in Computer Vision from Jean Monnet university of Saint-Étienne in 2001. In 2001, he was a researcher in the Laboratoire Central des Ponts et Chaussées (LCPC). In 2002, he was a system engineer in Chicago (USA). He is currently an engineer for the french ministry of transports.
Didier Aubert received the M.S. and Ph.D. degree, respectively, in 1985 and 1989 from the National Polytechnical Institut of Grenoble (INPG). From 1989--1990, he worked as a research scientist on the development of an automatic road following system for the NAVLAB at Carnegie Mellon University. From 1990–1994, he worked in the research department of a private company (ITMI). During this period he was the project leader of several projects dealing with computer vision. He is currently a researcher at INRETS since 1995 and works on Road traffic measurements, crowd monitoring, automated highway systems, and driving assistance systems for vehicles. He is an image processing expert for several companies, teaches at Universities (Paris VI, Paris XI, ENPC, ENST) and is at the editorial board of RTS (Research - Transport - Safety). 相似文献
16.
This article addresses the computation of invariant control laws [A. Fradkov, I. Miroshnik, V. Nikiforov, Nonlinear and Adaptive Control of Complex Systems, Kluwer, 1999] for fed-batch fermenters represented by two standard models. It will be shown how to derive partial state feedbacks that, assuming ideal conditions and perfect model, keep the specific growth rate μ constant provided the initial conditions are adequate. The invariant control law is the closed loop version of the exponential feeding already suggested in several references as shown later. The paper presents an analysis of invariance and a study of global stability within the framework of partial stability. That is, stability with respect to some of the state variables. This enables us to treat the case with Haldane-like or non-monotonous kinetics. 相似文献
17.
要培养学生的创造力,教师主要起引导作用。应提倡感性的观察方法与理性的表现相结合。从构图阶段开始就应该贯穿创新意念,鼓励学生采用大胆新奇的构图,以独特的视觉去观察对象、设计函面,充分发挥学生的主观能动性。 相似文献
18.
19.
20.
分析了河北冶金近期行业发展特别关注的几个问题:钢铁生产发展过快;产业结构缺陷,资源供应和环境压力。同时,文章从分析国内外市场形势和国家宏观政策形势入手,提出了河北冶金工业对产品结构调整,工艺装备调整和组织结构调整的必要性,任务和需注意的问题。 相似文献