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   1798篇
  免费   71篇
  国内免费   2篇
电工技术   13篇
综合类   1篇
化学工业   315篇
金属工艺   42篇
机械仪表   23篇
建筑科学   62篇
矿业工程   9篇
能源动力   46篇
轻工业   137篇
水利工程   15篇
石油天然气   7篇
无线电   159篇
一般工业技术   367篇
冶金工业   433篇
原子能技术   15篇
自动化技术   227篇
  2023年   13篇
  2022年   27篇
  2021年   36篇
  2020年   36篇
  2019年   41篇
  2018年   49篇
  2017年   44篇
  2016年   40篇
  2015年   30篇
  2014年   49篇
  2013年   88篇
  2012年   81篇
  2011年   117篇
  2010年   86篇
  2009年   58篇
  2008年   101篇
  2007年   75篇
  2006年   69篇
  2005年   72篇
  2004年   56篇
  2003年   65篇
  2002年   45篇
  2001年   26篇
  2000年   33篇
  1999年   33篇
  1998年   26篇
  1997年   35篇
  1996年   36篇
  1995年   26篇
  1994年   30篇
  1993年   20篇
  1992年   19篇
  1991年   11篇
  1990年   22篇
  1989年   22篇
  1988年   18篇
  1987年   14篇
  1986年   9篇
  1985年   17篇
  1984年   13篇
  1983年   25篇
  1982年   12篇
  1981年   13篇
  1980年   9篇
  1979年   26篇
  1978年   15篇
  1977年   17篇
  1976年   9篇
  1973年   8篇
  1972年   8篇
排序方式: 共有1871条查询结果,搜索用时 0 毫秒
51.
A number of different cues allow listeners to perceive musical meter. Three experiments examined effects of melodic and temporal accents on perceived meter in excerpts from folk songs scored in 6/8 or 3/4 meter. Participants matched excerpts with 1 of 2 metrical drum accompaniments. Melodic accents included contour change, melodic leaps, registral extreme, melodic repetition, and harmonic rhythm. Two experiments with isochronous melodies showed that contour change and melodic repetition predicted judgments. For longer melodies in the 2nd experiment, variables predicted judgments best at the beginning of excerpts. The final experiment, with rhythmically varied melodies, showed that temporal accents, tempo, and contour change were the strongest predictors of meter. The authors' findings suggest that listeners combine multiple melodic and temporal features to perceive musical meter. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
Speech Recognition is frequently cited as a potential remedy to distraction resulting from drivers' operation of in-vehicle devices. This position typically assumes that the introduction of speech recognition will result in reduced cognitive workload and improved driving performance. Past research neither fully supports nor fully discounts this assumption. However, it is difficult to compare many of these studies, due to differences in device operation tasks, the pacing of those tasks, speech recognition system performance, and system interface designs. In an effort to directly address the effect of voice recognition on driver distraction, the present authors developed a capability to manipulate the performance characteristics of a speech recognition system through a Wizard of Oz speech recognition system and installed this system in a simulated driving environment. The sensitivity of the simulated driving environment and speech recognition accuracy manipulation were evaluated in an initial study comparing driver cognitive workload and driving performance during self-paced simulated operation of a personal digital assistant (PDA) during no PDA use, manual control of the PDA, and speech control of the PDA. In the Speech PDA condition, speech recognition accuracy was varied between drivers. Analysis of drivers' emergency braking response times and rated cognitive workload revealed significantly lower cognitive demand and better performance in the No PDA condition when compared to the Manual PDA condition. The Speech PDA condition resulted in response times and rated cognitive workload levels that were between the No PDA and Manual PDA conditions, but not significantly different from either of these conditions. Further analysis of emergency braking performance revealed a non-significant trend towards better performance in conjunction with higher speech recognition accuracy levels. The potential for reducing driver distraction through the careful development and evaluation of speech recognition systems is discussed.  相似文献   
53.
Siponimod (Mayzent®), a sphingosine 1-phosphate receptor (S1PR) modulator which prevents lymphocyte egress from lymphoid tissues, is approved for the treatment of relapsing-remitting and active secondary progressive multiple sclerosis. It can cross the blood–brain barrier (BBB) and selectively binds to S1PR1 and S1PR5 expressed by several cell populations of the central nervous system (CNS) including microglia. In multiple sclerosis, microglia are a key CNS cell population moving back and forth in a continuum of beneficial and deleterious states. On the one hand, they can contribute to neurorepair by clearing myelin debris, which is a prerequisite for remyelination and neuroprotection. On the other hand, they also participate in autoimmune inflammation and axonal degeneration by producing pro-inflammatory cytokines and molecules. In this study, we demonstrate that siponimod can modulate the microglial reaction to lipopolysaccharide-induced pro-inflammatory activation.  相似文献   
54.
Kinetics of oxytetracycline reaction with a hydrous manganese oxide   总被引:4,自引:0,他引:4  
Tetracycline antibiotics comprise a class of broad spectrum antimicrobial agents finding application in human therapy, animal husbandry, aquaculture, and fruit crop production. To better understand the processes affecting these antibiotics in soils and sediments, the kinetics of oxytetracycline transformation by a hydrous manganese oxide (MnO2) were investigated as a function of reactant concentration, pH, and temperature. Oxytetracycline was rapidly degraded by MnO2. Initial reaction rates exhibited pronounced pH-dependence, increasing as pH decreased. Reaction of oxytetracycline with MnO2 was accompanied by generation of Mn(II) ions, suggesting oxidative transformation of the antibiotic. At pH 5.6, apparent reaction orders for oxytetracycline and MnO2 were 0.7 and 0.8. Reaction order with respect to H+ was 0.6 between pH 4 and 9. Initial reaction rates increased by a factor of approximately 2.4 for 10 degrees C temperature increases; the apparent activation energy (60 kJ x mol(-1)) was consistent with a surface-controlled reaction. Reactivity of tetracycline antibiotics toward MnO2 increased in the following order: rolitetracyline oxytetracycline < or =tetracycline approximately meclocycline < chlortetracycline. The initial rate of chlortetracycline degradation by MnO2 was substantially larger than that of the other tetracycline antibiotics investigated. MnO2 reactivity toward oxytetracycline decreased with time; a retarded rate equation was used to describe oxytetracycline reaction with MnO2 under declining rate conditions. This study indicates that natural manganese oxides in soils and sediments are likely to promote appreciable degradation of tetracycline antibiotics, and that reaction rates are strongly dependent on reaction time scale and solution conditions.  相似文献   
55.
Eight adolescents (ages 13-18 years) who sustained traumatic brain injury (TBI) and eight gender- and age-matched typically developing (TD) adolescents underwent event-related functional MRI (fMRI) while performing a Sternberg letter recognition task. Encoding, maintenance, and retrieval were examined with memory loads of one or four items during imaging. Both groups performed above a 70% accuracy criterion and did not differ in performance. TD adolescents showed greater increase in frontal and parietal activation during high-load relative to low-load maintenance than the TBI group. The TBI patients showed greater increase in activation during high-load relative to low-load encoding and retrieval than the TD group. Results from this preliminary study suggest that the capability to differentially allocate neural resources according to memory load is disrupted by TBI for the maintenance subcomponent of working memory. The overrecruitment of frontal and extrafrontal regions during encoding and retrieval following TBI may represent a compensatory process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
56.
57.
We present fieldwork findings from the deployment of an interactive sensing system that supports the work of energy advisors who give face-to-face advice to low-income households in the UK. We focus on how the system and the data it produced are articulated in the interactions between professional energy advisors and their clients, and how they collaboratively anticipate, rehearse, and perform data work. In addition to documenting how the system was appropriated in advisory work, we elaborate the ‘overhead cost’ of building collaborative action into connected devices and sensing systems, and the commensurate need to support discrete workflows and accountability systems to enable the methodical incorporation of the IoT into collaborative action. We contribute an elaboration of the social, collaborative methods of data work relevant to those who seek to design and study collaborative IoT systems.  相似文献   
58.
We conducted an exploratory study that examines the use of shared mobile displays such as mobile projectors and tablets to support group activities. We compare how a small group of visitors use either a shared display or personal individual devices in a museum visit context, in both a navigation task and a media viewing task. Group proximity, decision making, leadership patterns, and interaction between group members as well as attitudes are analyzed. We report on various usage patterns observed with group use of shared displays and discuss user preferences in comparison with the non-shared handheld alternative. Results show how mobile shared displays can support and enhance the group experience, by providing a shared mobile environment. Mobile shared displays increase group cohesiveness as was shown by increased proximity and amount of discussion by participants. Users perceive the use of shared displays as both useful and enjoyable, with the caveat that many users still want to retain individual control. We discuss this trade-off between groupness and individual control, as well as provide an analysis of the relative advantages of each shared display option.  相似文献   
59.
60.
Food Science and Biotechnology - We analyzed the antimicrobial potential of a novel furan fatty acid, 7,10-epoxyoctadeca-7,9-dienoic acid (7,10-EODA) against methicillin-resistant and -sensitive S....  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