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   6246篇
  免费   489篇
  国内免费   11篇
电工技术   67篇
综合类   9篇
化学工业   2569篇
金属工艺   77篇
机械仪表   86篇
建筑科学   264篇
矿业工程   35篇
能源动力   161篇
轻工业   1145篇
水利工程   41篇
石油天然气   35篇
无线电   268篇
一般工业技术   953篇
冶金工业   358篇
原子能技术   21篇
自动化技术   657篇
  2024年   12篇
  2023年   58篇
  2022年   453篇
  2021年   776篇
  2020年   232篇
  2019年   216篇
  2018年   257篇
  2017年   208篇
  2016年   269篇
  2015年   225篇
  2014年   276篇
  2013年   455篇
  2012年   376篇
  2011年   417篇
  2010年   283篇
  2009年   275篇
  2008年   279篇
  2007年   246篇
  2006年   216篇
  2005年   154篇
  2004年   143篇
  2003年   114篇
  2002年   99篇
  2001年   59篇
  2000年   47篇
  1999年   59篇
  1998年   45篇
  1997年   48篇
  1996年   46篇
  1995年   42篇
  1994年   41篇
  1993年   33篇
  1992年   29篇
  1991年   18篇
  1990年   24篇
  1989年   13篇
  1988年   19篇
  1987年   14篇
  1986年   10篇
  1985年   19篇
  1984年   17篇
  1983年   19篇
  1982年   7篇
  1981年   12篇
  1980年   13篇
  1979年   10篇
  1977年   8篇
  1976年   7篇
  1967年   4篇
  1966年   5篇
排序方式: 共有6746条查询结果,搜索用时 100 毫秒
121.
Computational Visual Media - Accurate and temporally consistent modeling of human bodies is essential for a wide range of applications, including character animation, understanding human social...  相似文献   
122.
Introduction: The aim of this study was to analyze the selected psychosocial aspects of chronic kidney disease in children treated with hemodialysis (HD). Methods: The study included 25 children treated with HD aged 2 to 18 years and their parents. Data concerning the illness and socio‐demographic parameters was collected. We used the Paediatric Quality of Life Inventory (PedsQL) for patients and for their parents the PedsQL‐proxy version, General Health Questionnaire (GHQ‐12), Berlin Social Support Scales (BSSS), and the Caregivers Burden Scale (CBS) to evaluate health‐related quality of life (QoL) of HD children and their primary caregivers. Findings: In the PedsQL test, the QoL of HD children was lower than in healthy children. Children treated with HD assessed their QoL on the PedsQL questionnaire higher than the primary caregivers, on all subscales as well as an overall health‐related QoL. Scoring below 2 on the GHQ‐12 test was reported in 56% of mothers, which may indicate that psychological symptoms have intensified. There was no correlation between BSSS, CBS, and GHQ‐12. Discussion: The assessment of QoL in pediatric patients would allow for the earliest possible identification of their nonsomatic problems and irregularities. This could, consequently, contribute to improving QoL in both children with chronic kidney disease and their families.  相似文献   
123.
124.
By increasing the density of interfaces in NiAl–CrMo in situ composites, the mechanical properties can be significantly improved compared to conventionally cast material. The refined microstructure is achieved by manufacturing through electron beam powder bed fusion (PBF-EB). By varying the process parameters, an equiaxed or columnar cell morphology can be obtained, exhibiting a plate-like or an interconnected network of the (Cr,Mo) reinforcement phase which is embedded in a NiAl matrix. The microstructure of the different cell morphologies is investigated in detail using scanning electron microscope, transmission electron microscopy, and atom probe tomography. For both morphologies, the mechanical properties at elevated temperatures are analyzed by compression and creep experiments parallel and perpendicular to the building direction. In comparison to cast NiAl and NiAl–(Cr, Mo), the yield strength of the PBF-EB fabricated specimens is significantly improved at temperatures up to 1,027 °C. While the columnar morphology exhibits the best improved mechanical properties at high temperatures, the equiaxial morphology shows nearly ideal isotropic mechanical behavior, which is a substantial advantage over directionally solidified material.  相似文献   
125.
Hemispherical image sensors simplify lens designs, reduce optical aberrations, and improve image resolution for compact wide-field-of-view cameras. To achieve hemispherical image sensors, organic materials are promising candidates due to the following advantages: tunability of optoelectronic/spectral response and low-temperature low-cost processes. Here, a photolithographic process is developed to prepare a hemispherical image sensor array using organic thin film photomemory transistors with a density of 308 pixels per square centimeter. This design includes only one photomemory transistor as a single active pixel, in contrast to the conventional pixel architecture, consisting of select/readout/reset transistors and a photodiode. The organic photomemory transistor, comprising light-sensitive organic semiconductor and charge-trapping dielectric, is able to achieve a linear photoresponse (light intensity range, from 1 to 50 W m−2), along with a responsivity as high as 1.6 A W−1 (wavelength = 465 nm) for a dark current of 0.24 A m−2 (drain voltage = −1.5 V). These observed values represent the best responsivity for similar dark currents among all the reported hemispherical image sensor arrays to date. A transfer method was further developed that does not damage organic materials for hemispherical organic photomemory transistor arrays. These developed techniques are scalable and are amenable for other high-resolution 3D organic semiconductor devices.  相似文献   
126.
127.
The ageing of populations has been a topic of discussion during the last few decades, but how is this subject represented in the media, and what images of old age are produced? In this article we present the results of a quantitative content analysis that investigates how the concept of population ageing has been represented in Swedish local and national daily news press between 1988 and 2009, and the old age positions that are offered in these representations. We also use discourse analysis in order to qualitatively examine the ways in which the concept of population ageing is articulated in these news press articles and the old age positions that are thereby constituted. The results show that the concept is constituted as a naturalised expert concept, and is primarily used in order to contextualise articles about future political and economical difficulties or even crises. By articulating population ageing with both political policies, political economy and older people??s (as a group) reported need for care and services, population ageing was constituted as a political economic concern rather than a problem for the aged individual.  相似文献   
128.
129.
In the area of product design, sensory dominance can be defined as the relative importance of different sensory modalities for product experience. It is often assumed that vision dominates the other senses. In the present study, we asked 243 participants to describe their experiences with consumer products in various situations: while buying a product, after the first week, the first month, and the first year of usage. The data suggest that the dominant sensory modality depends on the period of product usage. At the moment of buying, vision is the most important modality, but during the usage the other sensory modalities gain importance. The roles of the different modalities during usage are product-dependent. Averaged over 93 products analyzed in this study, after one month of usage touch becomes more important than vision, and after one year vision, touch and audition appear to be equally important. We conclude that to create a long-lasting positive product experience, designers need to consider user-product interaction at different stages of product usage and to determine which sensory modality dominates product experience at each stage.  相似文献   
130.
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