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   276362篇
  免费   22365篇
  国内免费   12658篇
电工技术   16985篇
技术理论   24篇
综合类   18479篇
化学工业   45230篇
金属工艺   15822篇
机械仪表   17959篇
建筑科学   21409篇
矿业工程   8868篇
能源动力   7965篇
轻工业   16739篇
水利工程   4730篇
石油天然气   18512篇
武器工业   2406篇
无线电   30941篇
一般工业技术   32024篇
冶金工业   14432篇
原子能技术   2933篇
自动化技术   35927篇
  2024年   1235篇
  2023年   4459篇
  2022年   7784篇
  2021年   11069篇
  2020年   8558篇
  2019年   7168篇
  2018年   7970篇
  2017年   8990篇
  2016年   8110篇
  2015年   10939篇
  2014年   13806篇
  2013年   16387篇
  2012年   17721篇
  2011年   19131篇
  2010年   17031篇
  2009年   16174篇
  2008年   15703篇
  2007年   15049篇
  2006年   15314篇
  2005年   13153篇
  2004年   9134篇
  2003年   7938篇
  2002年   7231篇
  2001年   6456篇
  2000年   6542篇
  1999年   7164篇
  1998年   5873篇
  1997年   4802篇
  1996年   4504篇
  1995年   3755篇
  1994年   3007篇
  1993年   2142篇
  1992年   1677篇
  1991年   1309篇
  1990年   1019篇
  1989年   794篇
  1988年   584篇
  1987年   361篇
  1986年   308篇
  1985年   217篇
  1984年   146篇
  1983年   126篇
  1982年   139篇
  1981年   110篇
  1980年   76篇
  1979年   40篇
  1978年   28篇
  1977年   21篇
  1976年   39篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
As CMOS device dimensions scale down to 100 nm and beyond, the interface roughness between Si and SiO/sub 2/ has become critical to device performance and reliability. Si/SiO/sub 2/ interface roughness degrades channel mobility decreasing drive currents. The authors have used atomic force microscopy to study surface roughness in the processing of 0.16 /spl mu/m CMOS integrated circuits. All of the process steps that could potentially affect the interface roughness have been studied. The results show that oxidation is the major contributor to the interface roughness. The rms roughness is found to be linearly dependent on oxide thickness. Transistors with Si/SiO/sub 2/ interface rms roughness that has been reduced from 1.6 to 1.1 /spl Aring/ by reducing oxide thicknesses show improved device drive currents. This technique for interfacial smoothing and device performance improvement has the advantage of being easily implemented in today's technology.  相似文献   
72.
73.
74.
A novel soft decision-based median subtraction filter is presented for clutter suppression and infrared (IR) point targets enhancement. The decision is made based on a jump Markov model and its state and parameter estimation using a particle filter. The scheme is compared with other conventional clutter background removal techniques and good results are obtained.  相似文献   
75.
76.
本文提出在安替比林存在下,以3,5-diBr-PADAP为显色剂,分光光度测定微量锆的新方法。在pH1~2的HCl介质中,锆(W)与试剂和安替比林形成配合比为1:1:1的红色三元配合物,最大吸收值在615nm波长处,摩尔吸光系数ε=1.35×10~5。锆(Ⅳ)量在0~25μg/25ml范围内,遵守比尔定律。方法简单、快速、准确。若采用钽试剂—苯萃取法分离共存离子,可适用于钽铌矿和合金中痕量锆的测定。  相似文献   
77.
本文阐述对贵冶动力车间二期反渗透进行改造的成功实践 ,主要从反渗透系统设计、反渗透系统中容易出现的问题及解决方法等进行介绍。  相似文献   
78.
因:用地为东西向长达470m的长条形,其北侧紧邻城市干道。  相似文献   
79.
A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow.  相似文献   
80.
Parylene is an emerging material for MEMS. It is an organic material that is grown by using the chemical vapor deposition method at room temperature. The deposition thickness is commonly controlled by the amount of solid-phase dimer loaded in a sublimation chamber. In a conventional deposition machine, the end point of the process is designated by the moment the dimer is exhausted. However, this end-of-process criterion does not offer precise, repeatable control of film thickness. We present the results of the development of an in situ end-point detector for a Parylene chemical vapor deposition process. The detector is based on the thermal transfer principle and can be implemented on commercial parylene deposition systems with minimal system modification. Such a sensor enables a user to stop the deposition when a targeted thickness is reached. The end point detector is very simple to implement on existing parylene deposition systems. A series of such sensors with different target deposition thickness would allow extraction of the actual deposition rate within a deposition run.  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