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   54184篇
  免费   4163篇
  国内免费   2017篇
电工技术   2813篇
技术理论   5篇
综合类   3010篇
化学工业   9382篇
金属工艺   3247篇
机械仪表   3249篇
建筑科学   3845篇
矿业工程   1772篇
能源动力   1692篇
轻工业   3788篇
水利工程   871篇
石油天然气   3788篇
武器工业   402篇
无线电   5852篇
一般工业技术   6491篇
冶金工业   3047篇
原子能技术   665篇
自动化技术   6445篇
  2024年   246篇
  2023年   902篇
  2022年   1635篇
  2021年   2353篇
  2020年   1702篇
  2019年   1472篇
  2018年   1675篇
  2017年   1805篇
  2016年   1619篇
  2015年   2112篇
  2014年   2718篇
  2013年   3135篇
  2012年   3322篇
  2011年   3629篇
  2010年   3212篇
  2009年   2880篇
  2008年   2829篇
  2007年   2745篇
  2006年   2905篇
  2005年   2479篇
  2004年   1553篇
  2003年   1359篇
  2002年   1279篇
  2001年   1004篇
  2000年   1208篇
  1999年   1484篇
  1998年   1193篇
  1997年   1017篇
  1996年   1016篇
  1995年   894篇
  1994年   712篇
  1993年   473篇
  1992年   372篇
  1991年   302篇
  1990年   245篇
  1989年   197篇
  1988年   177篇
  1987年   111篇
  1986年   96篇
  1985年   64篇
  1984年   58篇
  1983年   39篇
  1982年   32篇
  1981年   30篇
  1980年   18篇
  1979年   7篇
  1978年   7篇
  1977年   10篇
  1976年   14篇
  1975年   4篇
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
961.
容错技术广泛应用于各个行业来保证系统的冗余和可靠性。文章在分析比较当前的双机容错系统的性能优缺点后,提出了一种全新的基于“层”模式的双机容错系统解决方案。按照这种模式,可以从链路层到应用层构建一个通用的系统级的双机容错系统。文章对其实现的关键技术进行了阐述。  相似文献   
962.
为了对不同厂商、不同类型的网络安全产品进行集中管理,文章将XML和组件化技术引入到网络安全管理技术当中,提出了一种基于WEB的集中式网络安全管理系统的构造方案,并对该系统的整体架构和关键技术等内容进行了详细阐述。  相似文献   
963.
964.
Efficient blue‐, green‐, and red‐light‐emitting organic diodes are fabricated using binuclear platinum complexes as phosphorescent dopants. The series of complexes used here have pyrazolate bridging ligands and the general formula CNPt(μ‐pz)2PtCN (where CN = 2‐(4′,6′‐difluorophenyl)pyridinato‐N,C2′, pz = pyrazole ( 1 ), 3‐methyl‐5‐tert‐butylpyrazole ( 2 ), and 3,5‐bis(tert‐butyl)pyrazole ( 3 )). The Pt–Pt distance in the complexes, which decreases in the order 1 > 2 > 3 , solely determines the electroluminescence color of the organic light‐emitting diodes (OLEDs). Blue OLEDs fabricated using 8 % 1 doped into a 3,5‐bis(N‐carbazolyl)benzene (mCP) host have a quantum efficiency of 4.3 % at 120 Cd m–2, a brightness of 3900 Cd m–2 at 12 V, and Commission Internationale de L'Eclairage (CIE) coordinates of (0.11, 0.24). Green and red OLEDs fabricated with 2 and 3 , respectively, also give high quantum efficiencies (~ 6.7 %), with CIE coordinates of (0.31, 0.63) and (0.59, 0.46), respectively. The current‐density–voltage characteristics of devices made using dopants 2 and 3 indicate that hole trapping is enhanced by short Pt–Pt distances (< 3.1 Å). Blue electrophosphorescence is achieved by taking advantage of the binuclear molecular geometry in order to suppress dopant intermolecular interactions. No evidence of low‐energy emission from aggregate states is observed in OLEDs made with 50 % 1 doped into mCP. OLEDs made using 100 % 1 as an emissive layer display red luminescence, which is believed to originate from distorted complexes with compressed Pt–Pt separations located in defect sites within the neat film. White OLEDs are fabricated using 1 and 3 in three different device architectures, either with one or two dopants in dual emissive layers or both dopants in a single emissive layer. All the white OLEDs have high quantum efficiency (~ 5 %) and brightness (~ 600 Cd m–2 at 10 V).  相似文献   
965.
随着广大电力企业IP数据网络的完善及IP集合通信技术的成熟,在统一的IP网络上实现语音、视频、数据已经成为不可逆转的趋势。随着下一代企业网(NGeN)的兴起,语音、视频和数据三种通信手段进一步融合,以IP集合通信的形态开始服务于广大电力用户。本文试图分析电力网络目前的现状,对未来电力企业网络发展趋势进行深层次探讨。  相似文献   
966.
介绍了高阻厚层反型外延片的一种实用生产技术,即在PE-2061S外延设备上,采取特殊的工艺控制在电阻率小于0.02Ω·cm的p型低阻衬底上实现了高阻厚层n型外延生长,外延层电阻率大于40Ω·cm,厚度大于100μm. 研究表明:该外延材料完全可以满足IGBT器件制作的需要.  相似文献   
967.
Confronted by the difficulties of the von Neumann bottleneck and memory wall, traditional computing systems are gradually inadequate for satisfying the demands of future data-intensive computing applications. Recently, memristors have emerged as promising candidates for advanced in-memory and neuromorphic computing, which pave one way for breaking through the dilemma of current computing architecture. Till now, varieties of functional materials have been developed for constructing high-performance memristors. Herein, the review focuses on the emerging 2D MXene materials-based memristors. First, the mainstream synthetic strategies and characterization methods of MXenes are introduced. Second, the different types of MXene-based memristive materials and their widely adopted switching mechanisms are overviewed. Third, the recent progress of MXene-based memristors for data storage, artificial synapses, neuromorphic computing, and logic circuits is comprehensively summarized. Finally, the challenges, development trends, and perspectives are discussed, aiming to provide guidelines for the preparation of novel MXene-based memristors and more engaging information technology applications.  相似文献   
968.
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy.  相似文献   
969.
Aqueous Zn-ion batteries have been considered as promising alternatives to Li-ion batteries due to their abundant reserves, low price, and high safety. However, Zn anode shows poor reversibility and cycling stability in most conventional aqueous electrolytes. Here, a new type of aqueous Zn-ion electrolyte based on ZnCl2–acetamide deep eutectic solvent with both environmental and economic friendliness has been prepared. The water molecule introduced in the “water-in-deep eutectic solvent” electrolyte could reduce the Zn2+ desolvation energy barrier by regulating Zn2+ solvation structure to promote uniform Zn nucleation. Zn anode shows improved electrochemical performance (≈98% Coulombic efficiency over 1000 cycles) in the electrolyte whose molar ratio of ZnCl2:acetamide:H2O is 1:3:1. The assembled full battery composed of phenazine cathode and Zn anode could stably cycle over 10 000 cycles with a high capacity retention of 85.7%. Overall, this work offers new insights into exploring new green electrolyte systems for Zn-ion batteries.  相似文献   
970.
以低压化学气相沉积(LPCVD)热壁立式炉为实验平台,由二氯硅烷和氨通过LPCVD工艺合成氮化硅薄膜,利用降温成膜提高氮化硅薄膜的膜厚均匀度.基于气体碰撞理论建立了氮化硅薄膜沉积速率与反应气体浓度的关系式.分析比较了LPCVD炉内不同升温速率沉积氮化硅薄膜的表面性能.发现在变温沉积阶段,选择合适的降温速率是实现薄膜沉积...  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