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   71130篇
  免费   7815篇
  国内免费   4457篇
电工技术   5411篇
技术理论   4篇
综合类   5994篇
化学工业   11074篇
金属工艺   4055篇
机械仪表   4600篇
建筑科学   5643篇
矿业工程   2224篇
能源动力   2121篇
轻工业   6971篇
水利工程   1640篇
石油天然气   3172篇
武器工业   795篇
无线电   8371篇
一般工业技术   7379篇
冶金工业   2619篇
原子能技术   704篇
自动化技术   10625篇
  2024年   512篇
  2023年   1661篇
  2022年   3173篇
  2021年   4116篇
  2020年   2929篇
  2019年   2293篇
  2018年   2452篇
  2017年   2632篇
  2016年   2270篇
  2015年   3392篇
  2014年   4057篇
  2013年   4485篇
  2012年   5295篇
  2011年   5409篇
  2010年   4736篇
  2009年   4531篇
  2008年   4300篇
  2007年   4027篇
  2006年   3617篇
  2005年   2956篇
  2004年   2190篇
  2003年   2080篇
  2002年   2338篇
  2001年   1897篇
  2000年   1305篇
  1999年   1033篇
  1998年   692篇
  1997年   603篇
  1996年   491篇
  1995年   412篇
  1994年   342篇
  1993年   252篇
  1992年   200篇
  1991年   155篇
  1990年   116篇
  1989年   82篇
  1988年   77篇
  1987年   51篇
  1986年   56篇
  1985年   21篇
  1984年   22篇
  1983年   14篇
  1982年   26篇
  1981年   20篇
  1980年   35篇
  1979年   14篇
  1978年   4篇
  1976年   8篇
  1959年   4篇
  1951年   10篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
To evaluate the impact of zinc sulfate (ZnSO4) concentration on the structural properties of the films, Cd1-xZnxS thin films were formed on glass substrates using chemical bath deposition (CBD) in this study. The effect of ZnSO4 precursor concentration on the surface morphology, optical properties, and morphological structure of the Cd1-xZnxS films was investigated. To study the impact of zinc doping content on the performance metrics of Cu(In1-xGax)Se2 (CIGS) cells in the experimental group and to improve the buffer layer thickness, simulations were run using one-dimensional solar cell capacitance simulator (SCAPS-1D) software.  相似文献   
72.
Precise adjustment of the pore size, damage repair, and efficient cleaning is all challenges for the wider application of inorganic membranes. This study reports a simple strategy of combining dry-wet spinning and electrosynthesis to fabricate stainless-steel metal–organic framework composite membranes characterized by customizable pore sizes, targeted reparability, and high catalytic activity for membrane cleaning. The membrane pore size can be precisely customized in the range of 14–212 nm at nanoscale, and damaged membranes can be repaired by targeted treatment in 120 s. In addition, advanced oxidation processes can be used to quickly clean the membrane and achieve 98% flux recovery. The synergistic actions of the membrane matrix and the selective layer increase the adsorption energy of active sites to oxidant, shorten the electron transfer cycle, and enhance the overall catalytic performance. This study can provide a new direction for the development of advanced membranes for water purification and high-efficiency membrane cleaning methods.  相似文献   
73.
Wang  Lin  Wang  Xin  Li  Tao  Zheng  Ruijuan  Zhu  Junlong  Zhang  Mingchuan 《Neural computing & applications》2023,35(11):8051-8063
Neural Computing and Applications - Adaptive (sub)gradient methods have received wide applications such as the training of deep networks. The square-root regret bounds are achieved in convex...  相似文献   
74.
Yiwei  Feng  Xin  Wang 《Wireless Personal Communications》2022,124(3):2771-2783
Wireless Personal Communications - In this paper, a scalable, plug-and-play (PnP) and system-stable synthesis control method is proposed for the AC island microgrid consisting of a distributed...  相似文献   
75.
Wan  Hang  Mao  Yingzhu  Cai  Yanpeng  Li  Ran  Feng  Jingjie  Yang  Huixia 《Engineering with Computers》2022,38(4):3169-3184
Engineering with Computers - Aerated flow characterized by complex mass transfer processes with multiple hydraulic properties is a common enviro-hydraulics phenomenon, which have a variety of...  相似文献   
76.
非光滑伪凸优化问题是一类比较特殊的非凸优化问题,常出现在各类科学与工程应用中,因此具有很大的研究价值.针对现有神经网络模型解决非光滑伪凸优化问题存在的不足,该文基于微分包含理论,提出一种新型单层递归神经网络模型.通过理论分析,证明了神经网络状态解在有限时间内收敛到可行域,且永驻其中,最终神经网络状态解收敛于原优化问题的最优解.最后,通过数值实验,验证了所提理论的有效性.与现有的神经网络相比,该文所提神经网络模型结构简单仅为单层,不需要提前计算罚参数,且对初始点选取没有任何特殊的要求.  相似文献   
77.
Ma  Chao  Wan  Minjie  Xu  Yunkai  Ren  Kan  Qian  Weixian  Chen  Qian  Gu  Guohua 《Applied Intelligence》2022,52(3):2785-2800
Applied Intelligence - Infrared target tracking plays an important role in both civil and military fields. The main challenges in designing a robust and high-precision tracker for infrared...  相似文献   
78.
Wang  Bilin  Wang  Shengsheng  Zhang  Zhe  Zhao  Xin  Fu  Zihao 《Applied Intelligence》2022,52(12):14070-14084
Applied Intelligence - Unsupervised Domain Adaptation (UDA) aims to transfer knowledge from a label-rich source domain to an unlabeled target domain with a different but related distribution....  相似文献   
79.
This authors of this article investigated the dynamic response of woven Kevlar®29/epoxy laminates subjected to the impact loading. The cylindrical aluminum foam projectile and steel projectile were used to exert the impulse on the laminates. Deformation/failure modes, deflections, strain histories, and failure mechanisms were obtained and discussed. The results showed that with the high toughness of Kevlar fiber, the deformation modes of the laminates exhibited some characteristics similar to the metal panel, such as large global deformation. The failure mechanisms like matrix failure, fiber splitting, and fibrillation were observed. These micron failures led to the macroscopic delamination and fracture of the laminates.  相似文献   
80.
A new type of hollow nanostructure featured double metal‐organic frameworks shells with metal nanoparticles (MNPs) is designed and fabricated by the methods of ship in a bottle and bottle around the ship. The nanostructure material, hereinafter denoted as Void@HKUST‐1/Pd@ZIF‐8, is confirmed by the analyses of photograph, transmission electron microscopy, scanning electron microscopy, powder X‐ray diffraction, inductively coupled plasma, and N2 sorption. It possesses various multifunctionally structural characteristics such as hollow cavity which can improve mass transfer, the adjacent of the inner HKUST‐1 shell to the void which enables the matrix of the shell to host and well disperse MNPs, and an outer ZIF‐8 shell which acts as protective layer against the leaching of MNPs and a sieve to guarantee molecular‐size selectivity. This makes the material eligible candidates for the heterogeneous catalyst. As a proof of concept, the liquid‐phase hydrogenation of olefins with different molecular sizes as a model reaction is employed. It demonstrates the efficient catalytic activity and size‐selectivity of Void@HKUST‐1/Pd@ZIF‐8.  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