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   402890篇
  免费   36053篇
  国内免费   20536篇
电工技术   27703篇
技术理论   21篇
综合类   28802篇
化学工业   63009篇
金属工艺   22533篇
机械仪表   25438篇
建筑科学   33658篇
矿业工程   11473篇
能源动力   11939篇
轻工业   27883篇
水利工程   8204篇
石油天然气   20571篇
武器工业   3600篇
无线电   48950篇
一般工业技术   45552篇
冶金工业   18573篇
原子能技术   4496篇
自动化技术   57074篇
  2024年   1524篇
  2023年   5955篇
  2022年   11502篇
  2021年   16410篇
  2020年   12041篇
  2019年   9891篇
  2018年   10948篇
  2017年   12577篇
  2016年   11207篇
  2015年   15884篇
  2014年   20384篇
  2013年   25087篇
  2012年   27242篇
  2011年   29492篇
  2010年   26341篇
  2009年   25244篇
  2008年   24556篇
  2007年   23416篇
  2006年   22677篇
  2005年   18953篇
  2004年   13475篇
  2003年   12369篇
  2002年   12492篇
  2001年   10998篇
  2000年   9180篇
  1999年   8921篇
  1998年   7329篇
  1997年   6030篇
  1996年   5542篇
  1995年   4649篇
  1994年   3859篇
  1993年   2879篇
  1992年   2265篇
  1991年   1656篇
  1990年   1330篇
  1989年   1137篇
  1988年   862篇
  1987年   601篇
  1986年   479篇
  1985年   377篇
  1984年   251篇
  1983年   213篇
  1982年   191篇
  1981年   184篇
  1980年   178篇
  1979年   127篇
  1978年   72篇
  1977年   72篇
  1976年   86篇
  1975年   46篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
Lin  Haicheng  Huang  Wantong  Zhao  Kun  Qiao  Shuang  Liu  Zheng  Wu  Jian  Chen  Xi  Ji  Shuai-Hua 《Nano Research》2020,13(1):133-137
Nano Research - The isostructural and isoelectronic transition-metal-dichalcogenides 1T-TaS2 and 1T-TaSe2 are layered materials with intricate electronic structures. Combining the molecular beam...  相似文献   
122.
With the ambition of solving the challenges of the shortage of fossil fuels and their associated environmental pollution, visible-light-driven splitting of water into hydrogen and oxygen using semiconductor photocatalysts has emerged as a promising technology to provide environmentally friendly energy vectors. Among the current library of developed photocatalysts, organic conjugated polymers present unique advantages of sufficient light-absorption efficiency, excellent stability, tunable electronic properties, and economic applicability. As a class of rising photocatalysts, organic conjugated polymers offer high flexibility in tuning the framework of the backbone and porosity to fulfill the requirements for photocatalytic applications. In the past decade, significant progress has been made in visible-light-driven water splitting employing organic conjugated polymers. The recent development of the structural design principles of organic conjugated polymers (including linear, crosslinked, and supramolecular self-assembled polymers) toward efficient photocatalytic hydrogen evolution, oxygen evolution, and overall water splitting is described, thus providing a comprehensive reference for the field. Finally, current challenges and perspectives are also discussed.  相似文献   
123.
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO.  相似文献   
124.
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active edge 1T‐MoS 2 / edge Ni ( OH ) 2 heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich edge 1T‐MoS 2 / edge Ni ( OH ) 2 sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions.  相似文献   
125.
Wireless Personal Communications - The traditional simultaneous wireless information and power transfer (SWIPT) system uses a part of signals to decode information, and the other part is used for...  相似文献   
126.
张林龙  张伟 《毛纺科技》2015,43(4):45-48
文章主要研究用水浸法提取落葵浆果天然染料及研究浸提液对羊毛织物的染色性能。以水为提取剂提取落葵浆果天然染料,探讨提取工艺中料液比、提取温度及时间等因素对落葵浆果天然染料提取效果的影响。研究结果表明,落葵浆果水浸提法优化工艺为:料液比1∶20、提取温度70℃、提取时间30 min。落葵浆果天然染料可以对羊毛织物进行染色,媒染染色与直接染色相比,染色深度深且会呈现不同的颜色。由于媒染剂的络合作用,媒染染色色牢度比直接染色普遍高1~2级。  相似文献   
127.
128.
129.
130.
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