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   4251篇
  免费   506篇
  国内免费   168篇
电工技术   1147篇
综合类   428篇
化学工业   342篇
金属工艺   133篇
机械仪表   236篇
建筑科学   548篇
矿业工程   190篇
能源动力   83篇
轻工业   197篇
水利工程   110篇
石油天然气   185篇
武器工业   50篇
无线电   233篇
一般工业技术   161篇
冶金工业   258篇
原子能技术   33篇
自动化技术   591篇
  2024年   11篇
  2023年   40篇
  2022年   80篇
  2021年   95篇
  2020年   114篇
  2019年   88篇
  2018年   67篇
  2017年   115篇
  2016年   139篇
  2015年   150篇
  2014年   275篇
  2013年   210篇
  2012年   301篇
  2011年   352篇
  2010年   274篇
  2009年   285篇
  2008年   241篇
  2007年   320篇
  2006年   291篇
  2005年   231篇
  2004年   196篇
  2003年   188篇
  2002年   149篇
  2001年   149篇
  2000年   124篇
  1999年   76篇
  1998年   67篇
  1997年   54篇
  1996年   47篇
  1995年   54篇
  1994年   22篇
  1993年   23篇
  1992年   17篇
  1991年   10篇
  1990年   9篇
  1989年   8篇
  1988年   6篇
  1987年   6篇
  1986年   3篇
  1985年   3篇
  1983年   3篇
  1978年   3篇
  1966年   3篇
  1965年   3篇
  1964年   2篇
  1961年   3篇
  1960年   3篇
  1959年   2篇
  1958年   2篇
  1957年   2篇
排序方式: 共有4925条查询结果,搜索用时 15 毫秒
1.
Online configuration of large-scale systems such as networks requires parameter optimization within a limited amount of time, especially when configuration is needed as a response to recover from a failure in the system. To quickly configure such systems in an online manner, we propose a Probabilistic Trans-Algorithmic Search (PTAS) framework which leverages multiple optimization search algorithms in an iterative manner. PTAS applies a search algorithm to determine how to best distribute available experiment budget among multiple optimization search algorithms. It allocates an experiment budget to each available search algorithm and observes its performance on the system-at-hand. PTAS then probabilistically reallocates the experiment budget for the next round proportional to each algorithm’s performance relative to the rest of the algorithms. This “roulette wheel” approach probabilistically favors the more successful algorithm in the next round. Following each round, the PTAS framework “transfers” the best result(s) among the individual algorithms, making our framework a trans-algorithmic one. PTAS thus aims to systematize how to “search for the best search” and hybridize a set of search algorithms to attain a better search. We use three individual search algorithms, i.e., Recursive Random Search (RRS) (Ye and Kalyanaraman, 2004), Simulated Annealing (SA) (Laarhoven and Aarts, 1987), and Genetic Algorithm (GA) (Goldberg, 1989), and compare PTAS against the performance of RRS, GA, and SA. We show the performance of PTAS on well-known benchmark objective functions including scenarios where the objective function changes in the middle of the optimization process. To illustrate applicability of our framework to automated network management, we apply PTAS on the problem of optimizing link weights of an intra-domain routing protocol on three different topologies obtained from the Rocketfuel dataset. We also apply PTAS on the problem of optimizing aggregate throughput of a wireless ad hoc network by tuning datarates of traffic sources. Our experiments show that PTAS successfully picks the best performing algorithm, RRS or GA, and allocates the time wisely. Further, our results show that PTAS’ performance is not transient and steadily improves as more time is available for search.  相似文献   
2.
通过对具有不同骨架L径、陶瓷浆料组分在不同温度下烧结的三维连通网络陶瓷的电导率和电磁参数的测量,研究了对这种网络结构材料电磁参量的影响因素.结果表明,当三维连通网络陶瓷的电导率为10-4<σ<101S/cm时,其电损耗及感应磁损耗较大.三维连通网络陶瓷在高温下有较大的介电损耗特性,使其成为耐高温电吸波材料的理想选择.  相似文献   
3.
柴淑玲  任明霞 《山西建筑》2003,29(8):133-134
对智能电动机控制器的情况作了介绍,结合工作实践提出了维护要点和建议,并对该控制器的参数设置进行了说明,这对使用该设备的工业企业有一定的指导意义。  相似文献   
4.
Critical current measurements for three polycrystalline rings of YBCO, three Bi-2223, and one YBCO + Ag were developed from a temperature close to 80 K to the critical temperature using a previously reported contactless inductive device based on the transformer method. These data were used to analyze the ability of this device to characterize, in superconducting rings, the Ginzburg-Landau, Ambegaokar-Baratoff, and De Gennes regimes as well as the crossover temperature between them.  相似文献   
5.
What do health care practitioners need to know about providing adequate care for depressed minority women? This article examined the prevalence of depressive symptoms and clinical depression in ethnic minorities, the extent to which current health service utilization is congruent with needs, and the effectiveness of treatments provided to ethnic minorities in the primary care setting. The impact of ethnic minority women's sociocultural context on symptom expression and help-seeking behavior is also discussed. Finally, the clinical implications for accurate assessment and treatment of ethnic minority women by both medical and mental health practitioners working in the primary care sector are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
通过在广东工业大学数学专业7年的专业调整实践,探索了广东工业大学应用数学学院以信息科学、统计科学为数学专业方向的社会时代背景,说明了各个专业方向培养的侧重点和就业前景,阐明了传统学科专业与新增专业方向的联系与区别。  相似文献   
7.
We present our machine learning system, that uses inductive logic programming techniques to learn how to identify transmembrane domains from amino acid sequences. Our system facilitates the use of operators such as ‘contains’, that act on entire sequences, rather than on individual elements of a sequence. The prediction accuracy of our new system is around 93%, and this compares favourably with earlier results. This work was carried out with the support of a research grant from ISIS, Fujitsu Laboratories.  相似文献   
8.
Disturbance of the grounding of the shaft of a turboset or its absence for technical reasons can result in failure, misoperation, limitation of the operating zone, errors or limitation of the sensitivity of devices for control and protection of exciting circuits from single-point leakage, and electroerosion of elements of the turboset structure. Measures for increasing the reliability of the grounding of the shaft are discussed. __________ Translated from élektricheskie Stantsii, No. 3, March 2006, pp. 61–66.  相似文献   
9.
Self-knowledge is a concept that is present in several philosophies. In this article, we consider the issue of whether or not a learning algorithm can in some sense possess self-knowledge. The question is answered affirmatively. Self-learning inductive inference algorithms are taken to be those that learn programs for their own algorithms, in addition to other functions.
La connaissance de soi est un concept qui se retrouve dans plusieurs philosophies. Dans cet article, les auteurs s'interrogent à savoir si un algorithme d' apprentissage peut dans une certaine mesure posséder la connaissance de soi. lis apportent une reponse positive a cette question. Les algorithmes d'inference inductive autodidactes sont ceux qui font l'apprentissage de programmes pour leurs propres algorithmes, en plus d' autres fonctions.  相似文献   
10.
可膨胀尾管悬挂器技术及其应用   总被引:8,自引:2,他引:6  
可膨胀管悬挂器(ELH)作为尾管固井、完井工艺中一项革新型工具,可以成功地解决常规悬挂器因其原理和结构特点带来的固井施工难题及重叠段固井质量差等问题,成为下一代悬挂器研究的重点。文中以实体膨胀悬挂器系统为例,介绍了其结构原理及应用情况。  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