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   111566篇
  免费   8513篇
  国内免费   4191篇
电工技术   5875篇
技术理论   11篇
综合类   6616篇
化学工业   18966篇
金属工艺   5808篇
机械仪表   6677篇
建筑科学   8642篇
矿业工程   3079篇
能源动力   3104篇
轻工业   6624篇
水利工程   1717篇
石油天然气   6235篇
武器工业   696篇
无线电   13969篇
一般工业技术   14247篇
冶金工业   5901篇
原子能技术   1237篇
自动化技术   14866篇
  2024年   435篇
  2023年   1752篇
  2022年   2889篇
  2021年   3973篇
  2020年   3055篇
  2019年   2591篇
  2018年   2991篇
  2017年   3373篇
  2016年   2942篇
  2015年   3864篇
  2014年   4893篇
  2013年   6257篇
  2012年   6570篇
  2011年   7184篇
  2010年   6249篇
  2009年   6173篇
  2008年   6166篇
  2007年   5748篇
  2006年   6040篇
  2005年   5419篇
  2004年   3693篇
  2003年   3199篇
  2002年   2849篇
  2001年   2764篇
  2000年   2874篇
  1999年   3389篇
  1998年   2913篇
  1997年   2553篇
  1996年   2295篇
  1995年   1929篇
  1994年   1554篇
  1993年   1225篇
  1992年   969篇
  1991年   738篇
  1990年   604篇
  1989年   503篇
  1988年   395篇
  1987年   294篇
  1986年   207篇
  1985年   177篇
  1984年   108篇
  1983年   81篇
  1982年   87篇
  1981年   57篇
  1980年   46篇
  1979年   32篇
  1978年   25篇
  1977年   25篇
  1976年   40篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
In this work, a quantitative analysis is applied to resolve the newly reported polarity-dependent charge-to-breakdown (Q/sub BD/) data from thick oxides of 6.8 nm down to ultrathin oxides of 1.9 nm. Three independent sets of Q/sub BD/ data, i.e., n/sup +/poly/NFET stressed under inversion and accumulation, and p/sup +/ poly/PFET under accumulation are carefully investigated. The Q/sub BD/ degradation observed for p-type anodes, either poly-Si or Si-substrate, can be nicely understood with the framework of maximum energy released by injected electrons. Thus, this work provides a universal and quantitative account for a variety of experimental observations in the time-to-breakdown (T/sub BD/) and Q/sub BD/ polarity-dependence of oxide breakdown.  相似文献   
152.
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   
153.
大颗粒尿素造粒工艺简介   总被引:4,自引:0,他引:4  
介绍了大颗粒尿素造粒工艺,着重介绍了荷兰NSM公司的流化床造粒技术和法国K-T公司的流化床转鼓造粒(FDG)技术。  相似文献   
154.
讨论了如何选择适当的规则,如何建立简洁实用的规则库,如何应用规则库.提出了四种主要的光学邻近矫正规则,在实验结果中列举了规则库中的部分数据.利用规则矫正后的版图光刻得到的硅片图形有了明显的改善.规则库的自动建立部分 (OPCL)是基于规则的光学邻近矫正系统的重要组成部分.  相似文献   
155.
赵邑新  尹霞  吴建平 《高技术通讯》2002,12(2):10-15,20
在分析路由协议的特性及其测试需求的基础上,提出利用窗口黑盒来描述被测协议,利用多通道测试方法扩展对被测实现的控制和观察,通过扩充参考实现增强系统的测试能力。将这些理论,技术应用于系统中,对路由协议开展了有效的测试活动,为国产高性能路由器的开发提供了有力的支持,也进一步增强了PITS系统的功能和适用性。  相似文献   
156.
In the present paper, the reversible effects between energy-absorbing and energy-reflecting states of chameleon-type building coatings were studied through demonstration of the layers’ properties using infrared thermal imaging of the layers when exposed to a sunlamp or temperature measurements of the layers during exposure to sunlight at different ambient temperatures. The reversible transforming mechanism between the energy-absorbing and energy-reflecting states of the chameleon-type building coatings was investigated with IR, Raman and 1H NMR spectroscopy. The infrared thermal image results showed that when reversibly thermochromic pigments were added to normal white building coatings, the chameleon-type building coatings could absorb energy from the sunlamp below a switching temperature of about 18°C. Absorption of energy from the sunlamp stopped automatically above the switching temperature. The results from exposure to solar radiation showed that when the temperature was below the switching temperature, the chameleon-type building coating could absorb almost the same amount of solar energy as an ordinary coloured coating, and when the temperature was above the switching temperature, the chameleon-type building coating could reflect more solar energy than the ordinary coloured coating. The above results showed that chameleon-type building coatings could contribute to a thermally comfortable building environment. The IR spectroscopy results showed that when the environmental temperature was below the switching temperature of 18°C, the lactone ring of the thermochromic pigment molecule would open and the band of C=O would almost disappear. Raman spectra indicated that the band of C–O in would move to the high wave number range. From 1H NMR spectra, it could be found that there was some action between the hydrogen of the hydroxyl and the structure of . During the lactone ring opening, the electron in the non-bond orbital would transit to the higher orbital and it could elongate the conjugated bridge, which would produce visible absorption and hence produce an energy-absorbing effect. However, when the environmental temperature was above the switching temperature of 18°C, the lactone ring in the molecule of the thermochromic pigment would close, the transited electron would transit back to the original orbital, hence the visible absorption would disappear, which would make the coating have an energy-reflecting effect.  相似文献   
157.
介绍一种新型光纤燃煤炉火焰检测器,阐述其系统组成及特点,并提出了基于模糊推理的多信号融合处理方法。  相似文献   
158.
测井新技术在四川油气勘探开发中的应用   总被引:1,自引:0,他引:1  
综述随着四川盆地油气勘探深入所面临的油气领域复杂和困难的技术问题,介绍应用测井新技术为四川油气开发解决了大量的技术难题,特别是在复杂缝,洞型储层的评价,井旁地质构造形态精细分析和地质,测井,地震多学科结合储层横向预测等3个方面所取得的良好应用效果。  相似文献   
159.
本文是对市场上几款高级便携式打印机主要性能特点的比较考察报告,包括:佳能生产的CanonBJC-70型便携式彩色喷墨打印机,惠普生产的HPDeskJet340型便携式彩色喷墨打印机和Pentax生产的Pentax PocketJet便携式打印机,后者必须使用热敏纸。  相似文献   
160.
The formula and program for calculating the total and negative first harmonic interaction impedance from the data of “large perturbation measurement” are given. This program is a part of the programs for CCTWT design.  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