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   285465篇
  免费   16283篇
  国内免费   8219篇
电工技术   12058篇
技术理论   14篇
综合类   13244篇
化学工业   46568篇
金属工艺   15120篇
机械仪表   14864篇
建筑科学   18499篇
矿业工程   5486篇
能源动力   6913篇
轻工业   16169篇
水利工程   4449篇
石油天然气   11432篇
武器工业   1350篇
无线电   34162篇
一般工业技术   42146篇
冶金工业   13462篇
原子能技术   2367篇
自动化技术   51664篇
  2024年   885篇
  2023年   3274篇
  2022年   5854篇
  2021年   7962篇
  2020年   5834篇
  2019年   5036篇
  2018年   18938篇
  2017年   18805篇
  2016年   15032篇
  2015年   7871篇
  2014年   9768篇
  2013年   12472篇
  2012年   15234篇
  2011年   22831篇
  2010年   19505篇
  2009年   16718篇
  2008年   17355篇
  2007年   17974篇
  2006年   10999篇
  2005年   10812篇
  2004年   7663篇
  2003年   6893篇
  2002年   5786篇
  2001年   4835篇
  2000年   5053篇
  1999年   5716篇
  1998年   5346篇
  1997年   4386篇
  1996年   4010篇
  1995年   3328篇
  1994年   2783篇
  1993年   2202篇
  1992年   1715篇
  1991年   1302篇
  1990年   1021篇
  1989年   879篇
  1988年   690篇
  1987年   497篇
  1986年   394篇
  1985年   335篇
  1984年   212篇
  1983年   198篇
  1982年   163篇
  1981年   145篇
  1980年   131篇
  1979年   97篇
  1977年   63篇
  1976年   77篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time and promising to be merged into other application systems. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   
72.
磷矿中七种金属元素的光谱法测定   总被引:2,自引:0,他引:2  
陈名樑 《山西冶金》2004,27(1):36-37
研究了磷矿样品中7种金属元素锰、钴、镍,锌、铬、钼及铋的分析方法,选择了灵敏度高干扰少的谱线,绘制出工作曲线,对样品进行了科学处理,不必进行化学分离即可对七种元素同时测定,经合成样分析、回收实验及样品测定,证明此方法精确可靠,其回收率在98%-102%之间。  相似文献   
73.
该文介绍了Mall的产生条件和国内发展概况,并结合实例分析,着重论述建筑设计方面的有关问题。  相似文献   
74.
A new type of piezoelectric linear motor incorporating a traveling wave has been developed. The linear motor is comprised of a stator and a carriage. The stator design, which consists of a meander-line structure and gear teeth mounted on the meander-line structure, is the focus of this article. The meander-line structure is constructed with bimorph actuators arranged in a line. These actuators are driven by two phased sets of alternating current (ac) in order to generate a traveling wave. The traveling wave is transferred to the gear teeth, by which the carriage is driven. Modeling of the stator is derived by use of a strain energy method. The performance of various materials is evaluated by analytical and experimental methods. The analytical and the experimental results are quite approximate. Modal analysis is investigated using ANSYS. Appropriate modes associated with ultrasonic levels of resonant frequency are selected to obtain desired motion and to enhance the output performance. Surface speed for various applied input voltage are studied and indicate a nearly linear relationship. The stator in combination with the carriage makes up the linear motor.  相似文献   
75.
76.
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry  相似文献   
77.
78.
79.
80.
Presents a model suitable for computing images of absorption cross sections of thick tissue structures illuminated at near infrared (NIR) wavelengths from tomographic projection data. Image reconstruction is accomplished by solving a system of linear equations derived from transport theory. Reconstruction results using different algebraic solvers are shown for anatomical maps of the breast, derived from magnetic resonance imaging data, containing two simulated pathologies, in which case qualitatively good reconstructions were obtained. Evaluation of magnetic resonance (MR) data to optimize NIR optical tomographic imaging methods and to assess the feasibility of a combined MR-optical measurement scheme is discussed  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