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   9798篇
  免费   896篇
  国内免费   34篇
电工技术   137篇
综合类   15篇
化学工业   2269篇
金属工艺   250篇
机械仪表   404篇
建筑科学   235篇
矿业工程   5篇
能源动力   420篇
轻工业   761篇
水利工程   34篇
石油天然气   4篇
无线电   1805篇
一般工业技术   2103篇
冶金工业   826篇
原子能技术   131篇
自动化技术   1329篇
  2024年   7篇
  2023年   91篇
  2022年   124篇
  2021年   244篇
  2020年   196篇
  2019年   240篇
  2018年   337篇
  2017年   258篇
  2016年   392篇
  2015年   328篇
  2014年   442篇
  2013年   693篇
  2012年   545篇
  2011年   714篇
  2010年   551篇
  2009年   564篇
  2008年   547篇
  2007年   438篇
  2006年   401篇
  2005年   329篇
  2004年   324篇
  2003年   286篇
  2002年   267篇
  2001年   231篇
  2000年   204篇
  1999年   215篇
  1998年   327篇
  1997年   243篇
  1996年   181篇
  1995年   139篇
  1994年   116篇
  1993年   85篇
  1992年   64篇
  1991年   64篇
  1990年   64篇
  1989年   59篇
  1988年   40篇
  1987年   48篇
  1986年   50篇
  1985年   35篇
  1984年   29篇
  1983年   29篇
  1982年   9篇
  1981年   21篇
  1980年   20篇
  1979年   12篇
  1978年   13篇
  1977年   19篇
  1976年   26篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Abstract— A highly bendable liquid‐crystal display was fabricated by using a multi‐functional elastomer substrate of self‐aligning LC molecules without any surface treatment. One of the two substrates is a plastic substrate while the other is a multi‐functional elastomer substrate produced by a replica‐molding technique. The multi‐functional elastomer substrate has pixel‐encapsulating walls that serve as spacers and provide mechanical stability and reproducibility against bending deformations. The highly bendable LCD demonstrates great flexibility, durability, and excellent electro‐optic performances in a highly bent state.  相似文献   
992.
Austenitic Fe-18Mn alloy was cyclically deformed at various total strain amplitudes. The structural changes induced by cyclic straining in Fe-18Mn alloy were investigated by transmission electron microscopy. At a low strain amplitude of 0.4%, the formation ofε-martensite associated with deformation twins and stacking faults was observed in this alloy. As the applied strain amplitude was increased to 1.0%,α′-martensite embryos were induced in the alloy investigated. These embryos coalesce into a lath structure upon subsequent cyclic deformation.  相似文献   
993.
994.
995.
996.
As discussed in this paper, a practical optical backplane system was demonstrated, using a waveguide-embedded optical backplane board, processing boards, and optical slots for board-to-board interconnection. A metal optical bench was used as a packaging die for the optical devices and the integrated circuit chips in both the transmitter and the receiver processing boards. The polymer waveguide was produced by means of a hot-embossing technique and was then embedded following a conventional lamination processes. The average propagation loss of these waveguides was approximately 0.1 dB/cm at 850 nm. The dimension and optical properties of the waveguide in an optical backplane board were unchanged after lamination. As connection components between transmitter/receiver processing boards and an optical backplane board, optical slots were used for easy and repeatable insertion and extraction of the boards with a micrometer-scale precision. A 1/spl times/4 850-nm vertical-cavity surface-emitting laser array was used with 2 dBm of output power for the transmitter and a p-i-n photodiode array for the receiver. This paper successfully demonstrates 8 Gb/s of data transmission between the transmitter processing board and the optical backplane board.  相似文献   
997.
本文是可见光激光二极管开发现状与市场的最后部分,主要介绍器件应用领域,产销量,价格与趋势.  相似文献   
998.
Attenuation imaging has the promise to become a measurement technique for ultrasound imaging systems more sophisticated than those we currently possess; however, the difficulties in using the presently available methods tend to limit this potential for the non-specialist. In our recent work, we have investigated the attenuation imaging problem, and have had some success with an alternative technique, namely, attenuation-velocity product imaging. In certain cases this can be an acceptable substitute for purely attenuation imaging, particularly for the soft tissues encountered in some diagnostic medical situations where the acoustic velocities of the various layers are all of approximately the same value. This article discusses our technique in detail, beginning with fundamental considerations. We make no unreasonable assumptions about the object under study, and yet are able to show the uniqueness of the solution and also deal effectively with the problem of multiple reflections. The data encountered in this experimental configuration have several intriguing properties, which allow us to draw some conclusions about acoustic imaging in general.  相似文献   
999.
The treatment of oxidized Cu surfaces using an alkanethiol as a reducing agent has been investigated. Exposure to a dilute solution of 1-decanethiol resulted in the complete removal and/or conversion of CuO and subsequent formation of a passivating thiolate film, a so-called self-assembled monolayer (SAM), on the underlying Cu/Cu2O surface as evidenced by x-ray photoelectron spectroscopy (XPS) analysis. Morphological changes, monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM), revealed transformation of the rough, porous CuO layer into a comparatively smooth Cu/Cu2O surface. Experiments performed on integrated circuit back-end-of-line (BEOL) die structures, comprising Cu/SiO2 bond pads used as substrates for Cu wire bonding, demonstrate the potential application of a thiol-based in-situ cleaning-passivation procedure in microelectronics.  相似文献   
1000.
This paper proposes new integer approximations of the lapped transforms, called the integer lapped transforms (ILT), and studies their applications to image coding. The ILT are derived from a set of orthogonal sinusoidal transforms having short integer coefficients, which can be implemented with simple integer arithmetic. By employing the same scaling constants in these integer sinusoidal transforms, integer versions of the lapped orthogonal transform (LOT), the lapped biorthogonal transform (LBT), and the hierarchical lapped biorthogonal transform (HLBT) are developed. The ILTs with 5-b integer coefficients are found to have similar coding gain (within 0.06 dB) and image coding performances as their real-valued counterparts. Furthermore, by representing these integer coefficients as sum of powers-of-two coefficients (SOPOT), multiplier-less lapped transforms with very low implementation complexity are obtained. In particular, the implementation of the eight-channel multiplier-less integer LOT (ILOT), LBT (ILBT), and HLBT (IHLBT) require 90 additions and 44 shifts, 98 additions and 59 shifts, and 70 additions and 38 shifts, respectively.  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