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   4820篇
  免费   264篇
  国内免费   12篇
电工技术   34篇
综合类   5篇
化学工业   1012篇
金属工艺   96篇
机械仪表   100篇
建筑科学   239篇
矿业工程   8篇
能源动力   153篇
轻工业   456篇
水利工程   47篇
石油天然气   18篇
武器工业   2篇
无线电   432篇
一般工业技术   889篇
冶金工业   835篇
原子能技术   28篇
自动化技术   742篇
  2024年   6篇
  2023年   42篇
  2022年   82篇
  2021年   137篇
  2020年   94篇
  2019年   111篇
  2018年   145篇
  2017年   126篇
  2016年   157篇
  2015年   118篇
  2014年   159篇
  2013年   275篇
  2012年   276篇
  2011年   339篇
  2010年   240篇
  2009年   264篇
  2008年   300篇
  2007年   285篇
  2006年   228篇
  2005年   240篇
  2004年   173篇
  2003年   148篇
  2002年   152篇
  2001年   75篇
  2000年   64篇
  1999年   58篇
  1998年   71篇
  1997年   62篇
  1996年   70篇
  1995年   52篇
  1994年   49篇
  1993年   50篇
  1992年   38篇
  1991年   28篇
  1990年   38篇
  1989年   38篇
  1988年   31篇
  1987年   41篇
  1986年   39篇
  1985年   32篇
  1984年   25篇
  1983年   27篇
  1982年   25篇
  1981年   13篇
  1980年   14篇
  1979年   9篇
  1978年   13篇
  1976年   9篇
  1975年   8篇
  1974年   5篇
排序方式: 共有5096条查询结果,搜索用时 15 毫秒
41.
In this paper we propose a novel built-in self-test (BIST) design for embedded SRAM cores. Our contribution includes a compact and efficient BIST circuit with diagnosis support and an automatic diagnostic system. The diagnosis module of our BIST circuit can capture the error syndromes as well as fault locations for the purposes of repair and fault/failure analysis. In addition, our design provides programmability for custom March algorithms with lower hardware cost. The combination of the on-line programming mode and diagnostic system dramatically reduces the effort in design debugging and yield enhancement. We have designed and implemented test chips with our BIST design. Experimental results show that the area overhead of the proposed BIST design is only 2.4% for a 128 KB SRAM, and 0.65% for a 2 MB one.  相似文献   
42.
Important aspects in engineering gold nanoparticles for theranostic applications include the control of size, optical properties, cytotoxicity, biodistribution, and clearance. In this study, gold nanotubes with controlled length and tunable absorption in the near‐infrared (NIR) region have been exploited for applications as photothermal conversion agents and in vivo photoacoustic imaging contrast agents. A length‐controlled synthesis has been developed to fabricate gold nanotubes (NTs) with well‐defined shape (i.e., inner void and open ends), high crystallinity, and tunable NIR surface plasmon resonance. A coating of poly(sodium 4‐styrenesulfonate) (PSS) endows the nanotubes with colloidal stability and low cytotoxicity. The PSS‐coated Au NTs have the following characteristics: i) cellular uptake by colorectal cancer cells and macrophage cells, ii) photothermal ablation of cancer cells using single wavelength pulse laser irradiation, iii) excellent in vivo photoacoustic signal generation capability and accumulation at the tumor site, iv) hepatobiliary clearance within 72 h postintravenous injection. These results demonstrate that these PSS‐coated Au NTs have the ideal attributes to develop their potential as effective and safe in vivo imaging nanoprobes, photothermal conversion agents, and drug delivery vehicles. To the best of knowledge, this is the first in vitro and in vivo study of gold nanotubes.  相似文献   
43.
44.
Dears.  K 《电信科学》1996,12(11):9-13
本文介绍了ATM(异步转移模式)在公共网络中的作用,ATM在公共网络中的发展方向,最后着重讨论了公共ATM网络的要求。  相似文献   
45.
This paper demonstrates the feasibility of GPS-like ranging at terahertz (THz) frequencies. It is well established that GPS carrier signals are vulnerable to jamming via radio-frequency interference (RFI). As a result, there is a need for alternative radionavigation systems. THz signals offer a compelling option. Because of their high frequency (roughly ×100 higher than GPS), THz signals can be used to make highly precise range measurements. In addition, the large separation between the GPS and THz frequencies means that interference at GPS frequencies is very unlikely to impact the THz band. This paper lays the groundwork for a GPS-like ranging capability at THz frequencies. To this end, we identify key differences between THz hardware and GPS (radio frequency) hardware; we experimentally evaluate performance of a 0.30-THz system on a compact outdoor test range, and we introduce a measurement error model that highlights the distinctive role that multipath interference plays at THz frequencies.  相似文献   
46.
High resolution synchrotron-based core level spectroscopy was used to examine the energy level alignment at the interface of zinc–tetraphenylporphyrin films doped by the surface acceptor C60F48. Two distinct fluorofullerene charge states were identified, corresponding to ionized and neutral molecules, and their relative concentration as a function of coverage was used to evaluate the probability of occupation of the acceptor lowest unoccupied molecular orbital (LUMO). From an initial acceptor energy of ?0.25 eV, the C60F48 LUMO shifts upwards with coverage due to a doping-induced interfacial dipole potential, and stabilization of the LUMO at an energy 0.45 eV above the Fermi energy was obtained. While the energy difference upon saturation is consistent with the results obtained for other donor–acceptor systems that have been interpreted as Fermi level pinning, the present work shows that the energy offset is a direct consequence of the interplay between Fermi–Dirac statistics in combination with the interfacial dipole potential.  相似文献   
47.
Kevin 《数码》2005,(3):130-131
中国联通“世界风”的双模手机业务也推出一段日子了。CDMA/GSM左右逢源本是一件普天同庆的事,但由于机型的匮乏,业务尚末完善,使得双模手机一直给人雷声大雨点小的感觉。但这并未影响联通进行双模推广的步伐,一些最新的双模手机都在陆续的推出,各大厂商也是年初陆续发布了旗下最新的产品。本次《数码》率先拿到了两款最新的双模手机,分别是由宇龙通信公司出品的酷派(CoolPad)858和三星公司最新推出的W19。我们将会在下面的内容里作最详尽的评测。  相似文献   
48.
This letter is a supplement of the table of the minimal cost one-dimensional linear hybrid cellular automata with the maximum length cycle by Zhang, Miller, and Muzio [IEE Electronics Letters, 27(18):1625–1627, August 1991].This work was supported in part by Research Grants and Postgraduate Scholarships from the Natural Sciences and Engineering Research Council of Canada and by an equipment loan from the Canadian Microelectronics Corporation.  相似文献   
49.
A quantum‐tunneling metal‐insulator‐metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP‐CVD) for the first time. This scalable method is used to produce MIM diodes with high‐quality, pinhole‐free Al2O3 films more rapidly than by conventional vacuum‐based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum‐enabled devices. In fact, the MIM diodes fabricated by AP‐CVD show a lower effective barrier height (2.20 eV) at the electrode–insulator interface than those fabricated by conventional plasma‐enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero‐bias resistance, and better asymmetry of 107.  相似文献   
50.
The making of BaZrS3 thin films by molecular beam epitaxy (MBE) is demonstrated. BaZrS3 forms in the orthorhombic distorted-perovskite structure with corner-sharing ZrS6 octahedra. The single-step MBE process results in films smooth on the atomic scale, with near-perfect BaZrS3 stoichiometry and an atomically sharp interface with the LaAlO3 substrate. The films grow epitaxially via two competing growth modes: buffered epitaxy, with a self-assembled interface layer that relieves the epitaxial strain, and direct epitaxy, with rotated-cube-on-cube growth that accommodates the large lattice constant mismatch between the oxide and the sulfide perovskites. This work sets the stage for developing chalcogenide perovskites as a family of semiconductor alloys with properties that can be tuned with strain and composition in high-quality epitaxial thin films, as has been long-established for other systems including Si-Ge, III-Vs, and II-VIs. The methods demonstrated here also represent a revival of gas-source chalcogenide MBE.  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