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   521篇
  免费   26篇
电工技术   5篇
化学工业   170篇
金属工艺   11篇
机械仪表   20篇
建筑科学   8篇
矿业工程   3篇
能源动力   11篇
轻工业   17篇
无线电   37篇
一般工业技术   84篇
冶金工业   12篇
自动化技术   169篇
  2023年   2篇
  2022年   17篇
  2021年   19篇
  2020年   7篇
  2019年   10篇
  2018年   11篇
  2017年   5篇
  2016年   23篇
  2015年   15篇
  2014年   22篇
  2013年   31篇
  2012年   29篇
  2011年   38篇
  2010年   30篇
  2009年   27篇
  2008年   14篇
  2007年   26篇
  2006年   20篇
  2005年   21篇
  2004年   15篇
  2003年   18篇
  2002年   24篇
  2001年   6篇
  2000年   5篇
  1999年   7篇
  1998年   5篇
  1997年   6篇
  1996年   12篇
  1995年   6篇
  1994年   3篇
  1993年   7篇
  1992年   5篇
  1988年   3篇
  1987年   3篇
  1986年   5篇
  1985年   9篇
  1984年   7篇
  1983年   2篇
  1982年   5篇
  1980年   5篇
  1979年   6篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   4篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1963年   1篇
  1962年   1篇
排序方式: 共有547条查询结果,搜索用时 296 毫秒
61.
62.
63.
The previously described preparation of porous ion-exchange membranes (PIEM's) from the ternary blends of polyethylene interpolymer with poly(styrene-co-divinylbenzene) and polypropylene and calcium carbonate filler has been supplemented with the use of stearic acid and dibutyl phthalate as adhesion promoters. It was noted that both promoters govern the huge increase of pore diameter without any significant disturbances in the other PIEM's properties. The facilitating effect of chlorosulfonic acid diffusion toward calcium carbonate grains and large amounts of carbon dioxide volatilization was concluded. This is the basic point of pore creation to be discussed in this paper.  相似文献   
64.
In this paper a method of designing a pattern classifier in the presence of fuzzy data (patterns represented in a linguistic manner) is provided. The classifier formulas are studied in a general setting of fuzzy relation equations. Special attention is focused on feature ordering while coping with fuzziness.  相似文献   
65.
Mariposa: a wide-area distributed database system   总被引:7,自引:0,他引:7  
The requirements of wide-area distributed database systems differ dramatically from those of local-area network systems. In a wide-area network (WAN) configuration, individual sites usually report to different system administrators, have different access and charging algorithms, install site-specific data type extensions, and have different constraints on servicing remote requests. Typical of the last point are production transaction environments, which are fully engaged during normal business hours, and cannot take on additional load. Finally, there may be many sites participating in a WAN distributed DBMS. In this world, a single program performing global query optimization using a cost-based optimizer will not work well. Cost-based optimization does not respond well to site-specific type extension, access constraints, charging algorithms, and time-of-day constraints. Furthermore, traditional cost-based distributed optimizers do not scale well to a large number of possible processing sites. Since traditional distributed DBMSs have all used cost-based optimizers, they are not appropriate in a WAN environment, and a new architecture is required. We have proposed and implemented an economic paradigm as the solution to these issues in a new distributed DBMS called Mariposa. In this paper, we present the architecture and implementation of Mariposa and discuss early feedback on its operating characteristics. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Revised June 1995 / Accepted September 14, 1995  相似文献   
66.
The paper presents the results of investigation of organic sulphur occurrence in the coal of Upper Silesian coal basin. Six hundred coal samples from 52 mines were tested. It has been found that the content of organic sulphur in the coal depends on the stratigraphic layer, coalification grade and geographic location in the Upper Silesia region. The highest mean content of organic sulphur has been found in the most recent (ca. 0.85%) and in the oldest (ca. 0.5%) strata. The lowest mean contents of organic sulphur have been found in the intermediate strata. In the case of the most recent coals, the content of organic sulphur decreases with increasing of coalification grade. When the carbon content (Cdaf) exceeds 82%, the increase of coalification grade causes no further decrease of the mean content of organic sulphur. The share of organic sulphur in the total sulphur is lower in the case of more recent (<50%) and higher in the case of older coals (>50%).  相似文献   
67.
The paper deals with the applications of probabilistic sets in system theory, especially in system identification and the design of fuzzy logic controllers. Fuzzy systems described by means of fuzzy relational equations and Λ-fuzzy systems are discussed. The identification procedure is based on some ideas of clustering techniques and probabilistic sets. Numerical examples using fuzzy and nonfuzzy data are used to illustrate the theory.  相似文献   
68.
The free-volume theory of liquid solutions formulated by Flory and also by Patterson for binary systems, has been extended to ternary systems. Numerical calculations have been performed to test the validity of the approach, for a system of organic liquids, for a system of condensed gases, and also for a system of liquid metal alloys. Satisfactory results have been obtained in all cases. Thus, prediction of properties of ternary solutions from a limited number of data concerning pure components and binary mixtures was found possible.  相似文献   
69.
Witold Brostow 《Polymer》1983,24(5):631-638
A list of conclusions from experimental studies of drag reduction (DR) and mechanucal degradation in flow (MDF) is made. A statistical-mechanical model of chain conformations developed by the author9 is used, and its consequences for DR and MDF established. Experimental findings are explained in terms of the model, including those considered to be puzzling and contrary to expectations. A relation between the extent of mechanical degradation and flow time is derived. The equation obtained for relative drag reduction in function of time reproduces perfectly the experimental data for polystyrene+toluene solutions reported by Hunston and Zakin12. Some predictions from the present model have yet to be tested experimentally.  相似文献   
70.
A relationship between the impact transition temperatureT i and the stress concentration factorK s is derived. The relationship involves the temperature shift factora T; in turn,a T depends on the free volume. In earlier work in this problem Zewi and Corneliussen [6] utilized the W-L-F equation. Here a more direct relationship betweena T and the free volume is applied. Satisfactory values ofK s corresponding to givenT i are obtained for a wide temperature range; the range also includes temperatures below the glass transition pointT g. The opinion that a free volume exists between 0 K andT g is upheld.  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