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   59267篇
  免费   5396篇
  国内免费   3048篇
电工技术   4196篇
技术理论   5篇
综合类   4156篇
化学工业   9142篇
金属工艺   3515篇
机械仪表   3470篇
建筑科学   5186篇
矿业工程   1515篇
能源动力   1771篇
轻工业   3731篇
水利工程   1055篇
石油天然气   3134篇
武器工业   500篇
无线电   7304篇
一般工业技术   7306篇
冶金工业   2541篇
原子能技术   761篇
自动化技术   8423篇
  2024年   312篇
  2023年   1085篇
  2022年   1750篇
  2021年   2560篇
  2020年   1825篇
  2019年   1523篇
  2018年   1721篇
  2017年   1924篇
  2016年   1705篇
  2015年   2322篇
  2014年   2809篇
  2013年   3455篇
  2012年   3740篇
  2011年   3973篇
  2010年   3594篇
  2009年   3335篇
  2008年   3454篇
  2007年   3305篇
  2006年   3321篇
  2005年   2803篇
  2004年   1991篇
  2003年   1801篇
  2002年   1891篇
  2001年   1684篇
  2000年   1463篇
  1999年   1560篇
  1998年   1151篇
  1997年   1015篇
  1996年   992篇
  1995年   811篇
  1994年   665篇
  1993年   490篇
  1992年   440篇
  1991年   323篇
  1990年   215篇
  1989年   181篇
  1988年   157篇
  1987年   100篇
  1986年   65篇
  1985年   56篇
  1984年   34篇
  1983年   23篇
  1982年   32篇
  1981年   18篇
  1980年   19篇
  1979年   8篇
  1978年   2篇
  1959年   2篇
  1951年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
“Emergency medicine” is the front line of medical service a hospital provides; also it is the department people seek medical care from immediately after an emergency happens. The statistics by the Department of Health, Executive Yuan, indicate that over years, the number of people at the emergency department has been increasing. The US has introduced and practiced the triage system in the emergency medicine in 1960, whereby to aid the emergency department in allocating the patients, to give them appropriate medical care by the fast decision of the nurses and doctors in case of the patients’ seriousness through their judgment.This study takes on the knowledge contained in the massive data of unknown characteristics in the triage database at a Taiwanese regional hospital, using the cluster analysis and the rough set theory as tools for data mining to extract, with the analysis software ROSE2 (Rough Sets Data Explorer) and through rule induction technique, the imprecise, uncertain and vague information of rules from the massive database, and builds the model that is capable of simplifying massive data while maintaining the accuracy in classifying rules. After analyzing and evaluating the knowledge obtained from relevant mining in the hospitals past medical data for the consumption of emergency medical resources, this thesis proposes suggestions as reference for the hospitals in subsequent elevation of medical quality and decrease in operative costs.  相似文献   
92.
93.
94.
95.
This paper addresses the food distribution decision from a wholesaler's perspective, as the wholesalers are often faced with thorny issues such as when, where, how to deliver products at the lowest costs to best satisfy the retailers’ changing needs. This research relies on a distribution problem encountered at Northern Grocery Company in Beijing as an example to develop a two-stage solution procedure and subsequent computer-enabled programs for identifying efficient vehicle routing alternatives. The solution process, which integrates heuristic search algorithms and an integer programming model, can be applied to a wide range of distribution problems with specified route durations and a circular transportation network structure as exemplified by City of Beijing.  相似文献   
96.
97.
98.
Multimedia Tools and Applications - In this paper, we propose a novel low dimensional chaotic map, namely, compounded piecewise linear map (CPLM) in order to balance between security and...  相似文献   
99.
Reachability is one of the most important behavioral properties of Petri nets. We propose in this paper a novel approach for solving the fundamental equation in the reachability analysis of acyclic Petri nets, which has been known to be NP-complete. More specifically, by adopting a revised version of the cell enumeration method for an arrangement of hyperplanes in discrete geometry, we develop an efficient solution scheme to identify firing count vector solution(s) to the fundamental equation on a bounded integer set, with a complexity bound of O((nu)nm), where n is the number of transitions, m is the number of places and u is the upper bound of the number of firings for all individual transitions.  相似文献   
100.
Fixture, to hold an object by making multiple contacts, is a fundamental tool in manufacturing. A fixture layout is an arrangement of contacts on an object’s surface. Designing a fixture layout of an object can be reduced to computing the largest simplex and the resulting simplex is classified using the radius of the largest inscribed ball centered at the origin. We present three different algorithms to compute such a simplex: a simple randomized algorithm, an interchange algorithm, and a branch-and-bound algorithm. We also present methods to combine different algorithms to improve the performance and highlight their performance on complex 3D models consisting of thousands of triangles. Our randomized algorithm computes a feasible fixture layout in linear time and is well-suited for real-time applications. The interchange algorithm computes an optimal simplex in linear time such that no single vertex can be changed to enlarge the simplex, and it provides a practical method for complex 3D objects. The branch-and-bound algorithm computes the largest simplex by using lower and upper bounds on the radius of the inscribed ball, by which the computation time is reduced by a factor of five in comparison with the brute-force search.  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