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   777篇
  免费   28篇
  国内免费   2篇
电工技术   2篇
化学工业   179篇
金属工艺   10篇
机械仪表   30篇
建筑科学   37篇
能源动力   37篇
轻工业   66篇
水利工程   3篇
石油天然气   3篇
无线电   61篇
一般工业技术   172篇
冶金工业   90篇
原子能技术   9篇
自动化技术   108篇
  2023年   10篇
  2022年   17篇
  2021年   23篇
  2020年   20篇
  2019年   23篇
  2018年   34篇
  2017年   32篇
  2016年   26篇
  2015年   20篇
  2014年   37篇
  2013年   59篇
  2012年   28篇
  2011年   50篇
  2010年   32篇
  2009年   33篇
  2008年   44篇
  2007年   33篇
  2006年   29篇
  2005年   23篇
  2004年   18篇
  2003年   16篇
  2002年   13篇
  2001年   13篇
  2000年   7篇
  1999年   16篇
  1998年   24篇
  1997年   15篇
  1996年   14篇
  1995年   7篇
  1994年   10篇
  1993年   9篇
  1992年   5篇
  1991年   4篇
  1990年   4篇
  1989年   4篇
  1988年   7篇
  1987年   3篇
  1985年   4篇
  1984年   4篇
  1983年   6篇
  1982年   3篇
  1981年   6篇
  1980年   10篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1972年   2篇
  1971年   1篇
  1963年   1篇
排序方式: 共有807条查询结果,搜索用时 15 毫秒
51.
52.
53.
Transportation of goods in a supply chain from plants to customers through distribution centers (DCs) is modeled as a two-stage distribution problem in the literature. In this paper we propose genetic algorithms to solve a two-stage transportation problem with two different scenarios. The first scenario considers the per-unit transportation cost and the fixed cost associated with a route, coupled with unlimited capacity at every DC. The second scenario considers the opening cost of a distribution center, per-unit transportation cost from a given plant to a given DC and the per-unit transportation cost from the DC to a customer. Subsequently, an attempt is made to represent the two-stage fixed-charge transportation problem (Scenario-1) as a single-stage fixed-charge transportation problem and solve the resulting problem using our genetic algorithm. Many benchmark problem instances are solved using the proposed genetic algorithms and performances of these algorithms are compared with the respective best existing algorithms for the two scenarios. The results from computational experiments show that the proposed algorithms yield better solutions than the respective best existing algorithms for the two scenarios under consideration.  相似文献   
54.
Reviews the book, Generalized anxiety disorder: From science to practice by Michel J. Dugas and Melisa Robichaud (2006). The reviewers commend the authors for providing a comprehensive overview of GAD. Chapters include information on diagnosis, assessment techniques and treatment modules. Dugas and Robichaud refer to their treatment as primarily cognitive and emphasize the difference between their approach and other cognitive and cognitive-behavioural treatments for GAD. The treatment presented does not employ relaxation training or other strategies to reduce physical tension and overarousal. Rather, this treatment makes use of specific cognitive interventions with the understanding that physical and affective symptoms will decrease with corresponding reductions in excessive worry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
56.

At the chromosomal level of evolution, recombination is a major factor for genetic variations. However, recombination does not occur with equal frequency at various regions of genome. The recombination has the tendency to occur at specific region with higher frequency and with low frequency at other regions, and former regions are named as hot recombination regions whereas later are called cold regions for recombination. In this paper, we have developed supervised machine learning-based models using artificial neural network, support vector machine and Naïve Bayes for efficient and effective classification of such hot and cold recombination regions based on the nucleotide composition of sequences. All models were validated and tested using tenfold cross-validation. Furthermore, neural network model was validated using leave one out and random sampling techniques in addition to tenfold cross-validation. Moreover, models were evaluated using receiver-operating curve. Our results indicate that artificial neural network achieves the best result.

  相似文献   
57.
In this paper, we investigated synchronisation problem for stochastic Takagi–Sugeno (T-S) fuzzy complex networks model with discrete and distributed time delays. By constructing a new Lyapunov functional and employing Kronecker product, we developed delay-dependent synchronisation criterions. By applying stochastic analysis techniques, we derive starting conditions for synchronisation complex networks of the addressed with mixed time-varying delays and stochastic disturbances are achieved. A numerical examples are provided to demonstrate the effectiveness and usefulness of the proposed results.  相似文献   
58.
Recent advances in the fabrication of high-T c superconducting thick films demand processing techniques which can eliminate film/substrate interdifiusion that occurs during subsequent post-annealing heat treatment after the film is deposited, thereby limiting the application of the thick films for devices. The present study evaluates laser annealing techniques for plasma-deposited Y-Ba-Cu-O thick films using a high-energy CO2 laser (10.6m) in a continuous wave mode. The results are compared with those obtained by conventional furnace annealing techniques necessary for post-heat treatment of as-deposited superconducting thick films. The high-T c superconducting phase is recovered by cationic diffusion during subsequent post-annealing heat treatment. Crystallographic phases and microstructural characterization have been performed using XRD, SEM, and EPMA analytical techniques. The significance of the technology lies in the elimination of film/substrate interdiffusion problems, thereby resulting in high-quality superconducting thick films. The technology will significantly reduce the post-annealing times usually required by conventional furnace annealing techniques.  相似文献   
59.
Work breaks are known to have positive effects on employees’ health, performance and safety. Using a sample of twelve employees working in a stressful and cognitively demanding working environment, this experimental field study examined how different types of work breaks (boxing, deep relaxation and usual breaks) affect participants’ mood, cognitive performance and neurophysiological state compared to a control condition without any break. In a repeated measures experimental design, cognitive performance was assessed using an auditory oddball test and a Movement Detection Test. Brain cortical activity was recorded using electroencephalography. Individual’s mood was analysed using a profile of mood state. Although neurophysiological data showed improved relaxation of cortical state after boxing (vs. ‘no break’ and ‘deep relaxation’), neither performance nor mood assessment showed similar results. It remains questionable whether there is a universal work break type that has beneficial effects for all individuals.

Practitioner Summary: Research on work breaks and their positive effects on employees’ health and performance often disregards break activities. This experimental field study in a stressful working environment investigated the effect of different work break activities. A universal work break type that is beneficial for this workplace could not be identified.  相似文献   

60.
Book reviews     
Electronic Finance Law Chris Reed, 1993 Hemel Hempstead: Woodhead‐Faulkner. 450 pp. £50.00

Introduction to Computer Law, 2nd Edn David I. Bainbridge, 1993 London: Pitman £18.99

Deontic Logic in Computer Science: normative system specification John‐Jules CH. Meyer & Roel J. Wieringa, 1993 London: John Wiley £34.95, xiv + 317pp.  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