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   508篇
  免费   11篇
  国内免费   5篇
电工技术   3篇
综合类   4篇
化学工业   10篇
金属工艺   5篇
机械仪表   5篇
建筑科学   7篇
能源动力   7篇
轻工业   8篇
水利工程   1篇
石油天然气   1篇
无线电   79篇
一般工业技术   42篇
冶金工业   282篇
自动化技术   70篇
  2022年   4篇
  2021年   5篇
  2020年   5篇
  2019年   5篇
  2018年   5篇
  2017年   3篇
  2016年   2篇
  2015年   3篇
  2014年   3篇
  2013年   8篇
  2012年   6篇
  2011年   7篇
  2010年   9篇
  2009年   9篇
  2008年   27篇
  2007年   24篇
  2006年   13篇
  2005年   19篇
  2004年   18篇
  2003年   12篇
  2002年   5篇
  2001年   6篇
  2000年   3篇
  1999年   17篇
  1998年   69篇
  1997年   43篇
  1996年   47篇
  1995年   32篇
  1994年   26篇
  1993年   19篇
  1992年   4篇
  1991年   7篇
  1990年   5篇
  1989年   3篇
  1988年   5篇
  1987年   2篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1982年   1篇
  1981年   5篇
  1980年   4篇
  1979年   3篇
  1978年   2篇
  1977年   8篇
  1976年   8篇
  1971年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有524条查询结果,搜索用时 15 毫秒
21.
This paper presents a complete system for constructing panoramic image mosaics from sequences of images. Our mosaic representation associates a transformation matrix with each input image, rather than explicitly projecting all of the images onto a common surface (e.g., a cylinder). In particular, to construct a full view panorama, we introduce a rotational mosaic representation that associates a rotation matrix (and optionally a focal length) with each input image. A patch-based alignment algorithm is developed to quickly align two images given motion models. Techniques for estimating and refining camera focal lengths are also presented.In order to reduce accumulated registration errors, we apply global alignment (block adjustment) to the whole sequence of images, which results in an optimally registered image mosaic. To compensate for small amounts of motion parallax introduced by translations of the camera and other unmodeled distortions, we use a local alignment (deghosting) technique which warps each image based on the results of pairwise local image registrations. By combining both global and local alignment, we significantly improve the quality of our image mosaics, thereby enabling the creation of full view panoramic mosaics with hand-held cameras.We also present an inverse texture mapping algorithm for efficiently extracting environment maps from our panoramic image mosaics. By mapping the mosaic onto an arbitrary texture-mapped polyhedron surrounding the origin, we can explore the virtual environment using standard 3D graphics viewers and hardware without requiring special-purpose players.An erratum to this article can be found at  相似文献   
22.
A yeast identified as Saprochaete suaveolens was investigated for its capacity to produce a large panel of flavouring molecules. With a production of 32 compounds including 28 esters, S. suaveolens seems to be a good producer of fruity flavours and fragrances and especially of unsaturated esters, such as ethyl tiglate. Physiological and biochemical analyses were performed in this study in an attempt to comprehend the metabolic route to the formation of this compound. We show that the accumulation of ethyl tiglate by S. suaveolens is specifically induced by isoleucine. However, and contrary to S. cerevisiae, which harbours a classical Ehrlich pathway leading to the production of 2‐methylbutanol from isoleucine, our results provide phenotypic and enzymological evidence of ethyl tiglate biosynthesis in S. suaveolens through the catabolism of this amino acid by the β‐oxidation pathway, which generates tiglyl‐CoA as a probable intermediate. A kinetic analysis of this flavour molecule during growth of S. suaveolens on glucose and isoleucine showed a phase of production of ethyl tiglate that culminated concurrently with isoleucine exhaustion, followed by a disappearance of this compound, likely due to reassimilation by the yeast. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
23.
Attachment between parent and child plays a crucial role in the healthy development of the child. Accordingly disturbances in parental bonding will be linked with the development of mental disorders later in life. The present study examines the relationship between parental bonding and mental health in healthy adolescents. Participants were 847 Israeli high school students who completed the Parental Bonding Instrument (PBI), the Brief Symptom Inventory (BSI), the General Well-Being (GWB), the Perceived Social Support (PSS), and the Social Desirability scale (SDS). In general, Israeli adolescents reported more parental care and less control than did Australian adolescents and adults. Female subjects reported more maternal care than did males. Subjects who reported high care and low control (optimal bonding) reported less distress, better general well-being and better social support that did all other groups. In contrast, those who reported low care and high control (affectionless control bonding) had the highest BSI scores and the lowest GWB and PSS scores. These results are in line with Bowlby's theory of attachment. They also show that specific configuration of parental bonding are linked with distress and isolation in adolescents.  相似文献   
24.
PURPOSE: The aim of this study was to determine the concentration of interleukin-1 alpha in human embryo culture medium with or without oviductal cell coculture and to correlate the interleukin-1 alpha levels with pregnancy. METHODS: Culture media from 32 in vitro fertilization and embryo transfer cycles were assayed for interleukin-1 alpha by immunoassay technique. Human embryos were cultured in Earles' balanced salt solution supplemented with 15% preovulatory serum (sEBSS) in 16 of these cycles, while embryos in the rest of the cycles were cocultured with human oviductal cells in sEBSS. RESULTS: Both sEBSS and spent sEBSS after embryo culture contained low or undetectable levels of interleukin-1 alpha in the pregnant and nonpregnant cycles. On the other hand, oviductal cells significantly increased the amount of interleukin-1 alpha immunoreactivity in the conventional culture medium or coculture medium (P < 0.001, Mann-Whitney rank sum test). The concentrations of interleukin-1 alpha in the spent sEBSS after oviductal cell culture and after coculture with human embryos were 1.5 +/- 1.0 and 1.3 +/- 0.9 pg/ml, respectively. There was no difference in the interleukin-1 alpha concentration between the pregnant and the nonpregnant coculture cycles. CONCLUSIONS: These data showed that human oviductal cells produced interleukin-1 alpha immunoreactivity in a coculture system. However, this production could not be used as a marker for successful embryo implantation.  相似文献   
25.
26.
本文应用有限单元法,从生物力学的角度,揭示切牙在外力作用下,牙体、牙周膜内部的应力分布,从而为分析牙齿、牙周膜损伤,引起临床病变,提供理论依据。  相似文献   
27.
Xia  L. Shum  P. Lu  C. 《Electronics letters》2005,41(21):1165-1166
An apodised technique, applied in fibre distributed feedback laser design, is presented. With the proposed method, the unidirectional output power from the laser is maximised, and the power accumulation in the phase shift region is simultaneously greatly reduced.  相似文献   
28.
29.
A novel microstrip ring hybrid incorporating a PBG cell   总被引:1,自引:0,他引:1  
An experimental investigation of a novel compact microstrip 180° ring hybrid incorporating a one-dimensional (1-D) slow-wave structure, in the form of perforations on the ring itself, is presented. The size of the hybrid is reduced by 23% due to the slow-wave effect, and this size reduction technique has potential applications in MICs and MMICs. The measured insertion loss is comparable to that of a conventional microstrip hybrid  相似文献   
30.
It is by now familiar that in the deployment of solar photovoltaic (PV) systems, the cost dynamics of major system component like solar cell/module is subjected to experience curve effects driven by production learning and research and development at the supplier side. What is less clear, however, is the economics of system integration or system deployment that takes place locally close to the user, involving other market players, in the downstream solar PV value chain. Experts have agreed that suppliers of solar PV system must customize their flexible characteristics to address local unique users’ and applications requirements and compete on price/performance basis. A lack of understanding of the drivers of the economics of system customization therefore is a deficiency in our understanding of the overall economics of this renewable energy technology option.  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