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   524篇
  免费   33篇
  国内免费   4篇
电工技术   11篇
化学工业   150篇
金属工艺   21篇
机械仪表   10篇
建筑科学   24篇
矿业工程   1篇
能源动力   21篇
轻工业   67篇
水利工程   4篇
石油天然气   2篇
武器工业   1篇
无线电   43篇
一般工业技术   91篇
冶金工业   62篇
原子能技术   4篇
自动化技术   49篇
  2023年   2篇
  2022年   8篇
  2021年   25篇
  2020年   9篇
  2019年   9篇
  2018年   23篇
  2017年   19篇
  2016年   21篇
  2015年   21篇
  2014年   26篇
  2013年   44篇
  2012年   34篇
  2011年   40篇
  2010年   29篇
  2009年   33篇
  2008年   19篇
  2007年   23篇
  2006年   24篇
  2005年   8篇
  2004年   12篇
  2003年   7篇
  2002年   11篇
  2001年   6篇
  2000年   5篇
  1999年   5篇
  1998年   35篇
  1997年   16篇
  1996年   7篇
  1995年   6篇
  1994年   4篇
  1993年   6篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1986年   1篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1981年   1篇
  1977年   1篇
  1976年   3篇
  1974年   1篇
  1973年   2篇
排序方式: 共有561条查询结果,搜索用时 15 毫秒
1.
We study learning of predicate logics formulas from “elementary facts,” i.e. from the values of the predicates in the given model. Several models of learning are considered, but most of our attention is paid to learning with belief levels. We propose an axiom system which describes what we consider to be a human scientist's natural behavior when trying to explore these elementary facts. It is proved that no such system can be complete. However we believe that our axiom system is “practically” complete. Theorems presented in the paper in some sense confirm our hypothesis.  相似文献   
2.
Summary The complex 5-(C5H5)2Ti (1-OC(O)C6H5)2 was synthesized and activated with MA0 for ethylene polymerization. The resultant polymer is UHMW-PE with a viscosimetric molecular weight of Mv = 6.8 x 106 to 0.7 x 106 g/mol dependent on the temperature of the reaction. The effects of the Al/Ti molar ratio and temperature of the reaction on the catalytic activity and polymer properties were studied.  相似文献   
3.
Multimedia Tools and Applications - New mobile applications need to estimate user activities by using sensor data provided by smart wearable devices and deliver context-aware solutions to users...  相似文献   
4.
5.
6.
Structural optimization based on the shakedown theory is a powerful and promising technique. However, due to the nonlinearities of physical materials and the number of variable loads in real structures, it is computationally complex and time-consuming. To simplify the occurring non-linear, non-convex optimization problems, the paper suggests reducing the number of yield conditions. The so-called a yield criterion of the mean (integral yield condition) is analysed and explained in detail, which allows taking into account one yield condition for the entire finite element instead of multiple point-wise conditions. This approach shows promising results in numerical application to the optimization of a circular plate, considering a possibility of employing the yield criteria of the mean or pointwise yield conditions in different areas of the plate in particular. The methods applied are based on the assumptions of perfect plasticity and small deformations.  相似文献   
7.
An open-source software including an easy-to-use graphical user interface (GUI) has been developed for processing, modeling and mapping of gravity and magnetic data. The program, called Potensoft, is a set of functions written in MATLAB. The most common application of Potensoft is spatial and frequency domain filtering of gravity and magnetic data. The GUI helps the user easily change all the required parameters. One of the major advantages of the program is to display the input and processed maps in a preview window, thereby allowing the user to track the results during the ongoing process. Source codes can be modified depending on the users' goals. This paper discusses the main features of the program and its capabilities are demonstrated by means of illustrative examples. The main objective is to introduce and ensure usage of the developed package for academic, teaching and professional purposes.  相似文献   
8.
A displacement interferometer is described for measuring gauge blocks, in which a spatial filter is used to combine a laser beam with a white-light beam, and the length of the block is calculated from the phase differences of the laser signal corresponding to the centers of gravity of the achromatic fringes from the gauge and from the reference plate. __________ Translated from Izmeritel’naya Tekhnika, No. 9, pp. 3–5, September, 2006.  相似文献   
9.
Scientometrics - This study aims to validate an empirical model, at document level, that explains the interaction among content, usage, and citation within open access publications. The...  相似文献   
10.
Effective Co/Cu, CoB/Cu, and CoBM (M = Mo,Zn,Fe)/Cu catalysts were prepared on the copper surface by a simple electroless deposition method using a morpholine borane as a reducing agent in the glycine solution. The activity of the deposited catalysts was investigated for hydrogen generation from an alkaline sodium borohydride solution. It was determined that these synthesized catalysts demonstrated the catalytic activity for the hydrolysis reaction of NaBH4. The lowest obtained activation energy (EA) of the hydrolysis reaction of NaBH4was 27 kJ mol?1 for the CoBMo/Cu catalyst. The hydrogen generation rate of 15.30 ml min?1 was achieved using CoBMo/Cu catalysts at 313 K and it increased ~3.5 times with the increase of temperature to 343 K. The highest hydrogen generation rate obtained by CoBMo/Cu films may be related to the hierarchical cauliflower-shaped 3D structures and the high roughness surface area. Moreover, the CoBMo/Cu catalyst showed an excellent reusability.  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