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   193篇
  免费   5篇
化学工业   28篇
机械仪表   5篇
建筑科学   4篇
能源动力   8篇
轻工业   25篇
水利工程   1篇
石油天然气   1篇
无线电   8篇
一般工业技术   29篇
冶金工业   61篇
原子能技术   3篇
自动化技术   25篇
  2023年   3篇
  2022年   3篇
  2021年   13篇
  2019年   4篇
  2018年   8篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   4篇
  2013年   8篇
  2012年   10篇
  2011年   14篇
  2010年   12篇
  2009年   9篇
  2008年   11篇
  2007年   7篇
  2006年   5篇
  2005年   11篇
  2004年   10篇
  2003年   5篇
  2002年   8篇
  2001年   2篇
  2000年   5篇
  1999年   2篇
  1998年   4篇
  1997年   7篇
  1996年   3篇
  1995年   3篇
  1994年   1篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1976年   1篇
  1973年   1篇
  1967年   1篇
  1961年   1篇
排序方式: 共有198条查询结果,搜索用时 15 毫秒
1.
Evaluating the design of flexible manufacturing systems is complex. Developing a measure of performance useful for evaluating alternate designs continues to be interesting. Here, total productivity of the system is proposed as an appropriate measure. Specification of parameters based upon strategic considerations for this measure are discussed. Finally, the usefulness of the measure is demonstrated through an example.  相似文献   
2.
3.
Massively multiplayer online role‐playing game (MMORPG) addiction presents a serious issue worldwide and has attracted increasing attention from academic and other public communities. This article addresses this critical issue and fills research gaps by proposing and testing a research model of MMORPG addiction. Building on the conceptual foundation of the hedonic management model of addiction and the technology affordance perspective, we develop a research model explaining how MMORPG affordances (ie, achievement, social and immersion affordances) are associated with the duality of hedonic effects (ie, perceived positive mood enhancement and perceived negative mood reduction) and the extent of MMORPG addiction. Using structural equation modelling, we empirically test our research model with 406 MMORPG players. The results show that both perceived positive mood enhancement and perceived negative mood reduction positively correlate with the extent of MMORPG addiction. Furthermore, achievement and immersion affordances are positively associated with the duality of hedonic effects, whereas social affordance is not. Our study contributes to the growing body of technology addiction literature by revealing the relationships between the two hedonic effects and the extent of MMORPG addiction, and by offering a contextualised explanation of the role of MMORPG affordances in these relationships. We offer an alternative perspective on the far‐reaching, unintended relationships between technological affordances and addictive technology use. Our study provides game developers and policymakers with insights into preventing MMORPG addiction to create an entertaining, healthy virtual playground.  相似文献   
4.
The predominant method for smart phone accessing is confined to methods directing the authentication by means of Point-of-Entry that heavily depend on physiological biometrics like, fingerprint or face. Implicit continuous authentication initiating to be loftier to conventional authentication mechanisms by continuously confirming users’ identities on continuing basis and mark the instant at which an illegitimate hacker grasps dominance of the session. However, divergent issues remain unaddressed. This research aims to investigate the power of Deep Reinforcement Learning technique to implicit continuous authentication for mobile devices using a method called, Gaussian Weighted Cauchy Kriging-based Continuous Czekanowski’s (GWCK-CC). First, a Gaussian Weighted Non-local Mean Filter Preprocessing model is applied for reducing the noise present in the raw input face images. Cauchy Kriging Regression function is employed to reduce the dimensionality. Finally, Continuous Czekanowski’s Classification is utilized for proficient classification between the genuine user and attacker. By this way, the proposed GWCK-CC method achieves accurate authentication with minimum error rate and time. Experimental assessment of the proposed GWCK-CC method and existing methods are carried out with different factors by using UMDAA-02 Face Dataset. The results confirm that the proposed GWCK-CC method enhances authentication accuracy, by 9%, reduces the authentication time, and error rate by 44%, and 43% as compared to the existing methods.  相似文献   
5.
Early Head Start, a federal program begun in 1995 for low-income pregnant women and families with infants and toddlers, was evaluated through a randomized trial of 3,001 families in 17 programs. Interviews with primary caregivers, child assessments, and observations of parent-child interactions were completed when children were 3 years old. Caregivers were diverse in race-ethnicity, language, and other characteristics. Regression-adjusted impact analyses showed that 3-year-old program children performed better than did control children in cognitive and language development, displayed higher emotional engagement of the parent and sustained attention with play objects, and were lower in aggressive behavior. Compared with controls, Early Head Start parents were more emotionally supportive, provided more language and learning stimulation, read to their children more, and spanked less. The strongest and most numerous impacts were for programs that offered a mix of home-visiting and center-based services and that fully implemented the performance standards early. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Binder provides structural integrity by holding all ingredients in the composition of a brake friction material. The modified binders have played a major role in improving the frictional performance and thermal resistance of the friction material. The present research work evaluates the influence of secondary binders (Nitrile Butadiene rubber (NBR) and Styrene Butadiene rubber (SBR)) on the tribological performance of the friction material using a full-scale inertia brake dynamometer as per JASO C406 standard. Three brake pads were developed by varying the type and composition of secondary rubber binder (5%NBR, 5%SBR and 2.5%NBR + 2.5%SBR) with rest of the ingredients kept unaltered. It was found that the quantity of SBR rubber powder present as secondary binder improved dry and wet recovery. Friction coefficient (μ) exhibited better stability during the fade with the inclusion of both the rubber powders. The friction material with the inclusion of both the NBR and SBR rubber powders exhibited overall better performance than compared to the inclusion of only one secondary binder rubber in the composition. The worn-out surface of the developed friction materials and the counter discs were characterised using FESEM.  相似文献   
7.
8.
This study explored the relation between preschoolers' television exposure and one important indicator of cognitive processing called theory of mind (ToM). A total of 107 preschoolers and their parents provided data on the preschoolers' television exposure (including both intentional viewing and exposure via background television), parent–child discussion of television, and preschoolers' ToM. The results indicated that preschoolers who were exposed to more background television and who had a television in their bedroom performed more poorly on ToM assessments compared with other children. Parent–child discussion of television was positively related to ToM performance, however. These results have implications for how we understand the effects of television on preschoolers.  相似文献   
9.
Alfred A. Christy 《Lipids》2010,45(8):733-741
Isomers of conjugated linoleic acid from 7t9c through 12t14t can be induced by thermal treatment of triacylglycerol samples of 9c11t or 10t12c fatty acids in glass tubes. The formation of conjugated linoleic acids (CLAs) has been observed during thermal induction of the above-mentioned triacylglycerols at 250, 280 and 320°C. The concentrations of isomers formed in the mixture varied depending on the temperature and duration of the heating experiments. The objective of this study was to find a suitable thermal induction temperature and time that can produce most of the isomers of CLAs from the above-mentioned triacylglycerols. Such a mixture would give researchers a reference standard that can be used in the identification of CLAs in GC analyses of relevant samples. Fifteen-microlitre portions of the triacylglycerol samples containing 9c11t/10t12c fatty acid were placed in micro-glass ampoules, sealed under nitrogen and then subjected to thermal treatment. The glass ampoules were removed at regular time intervals, cut open, and part of the samples was analysed by infrared spectroscopy using attenuated internal reflectance technique. The remainder of the samples was subjected to derivatisation into their methyl esters. The methyl esters of the isomerised fatty acids were then analysed by gas chromatography after appropriate dilution in heptane. The results show that the thermally induced glyceride samples of 9c11t/10t12c fatty acids gave CLA profiles containing isomers ranging from 7t9c to 12t14t. However, the concentrations of the isomers are different depending on the duration of the thermal induction. It appears that [1,5] sigmatropic rearrangements and positional isomerisations take place in the heated mixtures. The rearrangements and positional isomerisations are accelerated by increasing temperature. The glyceride samples heated to 325°C form isomers within 30 min and provide a mixture of CLA isomers that can be used as reference sample containing the methyl esters of CLAs.  相似文献   
10.
This study used latent growth curve modeling to investigate whether the effects of gender and Greek involvement on alcohol use and problems over the first 2 years of college are best characterized by selection, socialization, or reciprocal influence processes. Three social influences (alcohol offers, social modeling, and perceived norms) were examined as potential mediators of these effects. Undergraduate participants (N = 388) completed self-report measures prior to enrollment and in the spring of their freshmen and sophomore years. Male gender and involvement in the Greek system were associated with greater alcohol use and problems prior to college. Both gender and Greek involvement significantly predicted increases in alcohol use and problems over the first 2 years of college. Cross-domain analyses provided strong support for a mediational role of each of the social influence constructs on alcohol use and problems prior to matriculation, and prematriculation social modeling and alcohol offers mediated relations between Greek involvement and changes in alcohol use over time. Findings suggest that students, particularly men, who affiliate with Greek organizations constitute an at-risk group prior to entering college, suggesting the need for selected interventions with this population, which should take place before or during the pledging process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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