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   440篇
  免费   17篇
电工技术   6篇
化学工业   56篇
金属工艺   11篇
机械仪表   9篇
建筑科学   26篇
矿业工程   4篇
能源动力   7篇
轻工业   59篇
水利工程   6篇
石油天然气   1篇
无线电   16篇
一般工业技术   65篇
冶金工业   77篇
原子能技术   4篇
自动化技术   110篇
  2024年   2篇
  2023年   4篇
  2022年   11篇
  2021年   14篇
  2020年   5篇
  2019年   15篇
  2018年   13篇
  2017年   11篇
  2016年   6篇
  2015年   17篇
  2014年   10篇
  2013年   30篇
  2012年   27篇
  2011年   22篇
  2010年   16篇
  2009年   17篇
  2008年   20篇
  2007年   15篇
  2006年   10篇
  2005年   11篇
  2004年   16篇
  2003年   9篇
  2002年   11篇
  2001年   12篇
  2000年   13篇
  1999年   12篇
  1998年   16篇
  1997年   10篇
  1996年   12篇
  1995年   6篇
  1994年   3篇
  1993年   6篇
  1992年   4篇
  1989年   2篇
  1988年   2篇
  1987年   5篇
  1986年   2篇
  1985年   10篇
  1984年   4篇
  1983年   5篇
  1981年   3篇
  1977年   3篇
  1976年   7篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1966年   1篇
  1961年   1篇
  1915年   1篇
排序方式: 共有457条查询结果,搜索用时 31 毫秒
1.
Software and Systems Modeling - Many model transformation scenarios require flexible execution strategies as they should produce models with the highest possible quality. At the same time,...  相似文献   
2.
Examined how the factors relative in-group size and relative outgroup size (i.e., minority vs. nonminority) affect the perception of in-group and out-group homogeneity. On the basis of social identity theory, we hypothesized that (a) members of minorities would perceive the in-group as more homogeneous than the out-group, whereas members of nonminorities would perceive the reverse; (b) this effect would be strongest on dimensions most strongly correlated with the social categorization; and (c) members of minorities would identify more strongly with their in-group than would members of nonminorities. 192 13–15 yr olds participated in the experiment. On the presumed basis of a perceptual task, approximately half were randomly allocated to minimal social categories, which differed in perceived size relative to an out-group (which also differed in perceived size). They were asked to estimate the homogeneity of the two groups on a number of dimensional attributes. The remaining (control) subjects gave similar estimates under identical conditions, except that they were not allocated to a category. The data confirmed all but the second hypothesis, which was only partially supported. The results were interpreted in terms of social identification processed. Results tend to rule out alternative explanations in terms of an inverse relation between group size and perceived group homogeneity, rating extremity, and in-group favoritism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
1前言及历史背景 为避免钢水造成燃烧或破碎引起对人体的可能伤害,必须对连铸平台的平面布置进行分析.  相似文献   
4.
Apprehensions of reduced wood quality could be repudiated to a large extent in “novel” forest decline areas. Comparatively little is known about wood from trees severely damaged by local emitters. In this sense ten lowly and highly fluoride affected pine trees (Pinus sylvestris L.) were sampled from a location in upper Austria, near an aluminium refining plant. In comparison with the lowly affected pines the highly affected one show significant reductions of wood properties under elimination of the influence of wood density and growth rate: Modulus of elasticity in bending, bending strength, maximum crushing strength, maximal tangential and volume swelling. The reductions are situated especially in the upper parts of the trunks. Practical usage of the wood has not decreased.  相似文献   
5.
We extend the Enestroumlm-Kakeya theorem and its refinement by Hurwitz to polynomial matrices with positive semidefinite coefficients. We determine an annular region containing the zeros of . A stability result for systems of linear difference equations is given as an application.  相似文献   
6.
Several compounds, structurally related to the insect growth regulator Fenoxycarb, exhibited interesting inhibition action to control proliferation of Trypanosoma cruzi, the parasite responsible for Chagas' disease. Some of these drugs were shown to be potent growth inhibitors of this parasite. All of these drugs had previously presented juvenoid activity on several non-related bug species such as Tenebrio molitor, Galleria mellonella, Dysdercus cingulatos, and Pyrrhocoris apterus.  相似文献   
7.
Tendinopathies are painful, disabling conditions that afflict 25% of the adult human population. Filling an unmet need for realistic large-animal models, we here present an ovine model of tendon injury for the comparative study of adult scarring repair and fetal regeneration. Complete regeneration of the fetal tendon within 28 days is demonstrated, while adult tendon defects remained macroscopically and histologically evident five months post-injury. In addition to a comprehensive histological assessment, proteome analyses of secretomes were performed. Confirming histological data, a specific and pronounced inflammation accompanied by activation of neutrophils in adult tendon defects was observed, corroborated by the significant up-regulation of pro-inflammatory factors, neutrophil attracting chemokines, the release of potentially tissue-damaging antimicrobial and extracellular matrix-degrading enzymes, and a response to oxidative stress. In contrast, secreted proteins of injured fetal tendons included proteins initiating the resolution of inflammation or promoting functional extracellular matrix production. These results demonstrate the power and relevance of our novel ovine fetal tendon regeneration model, which thus promises to accelerate research in the field. First insights from the model already support our molecular understanding of successful fetal tendon healing processes and may guide improved therapeutic strategies.  相似文献   
8.
We present a novel framework for the automatic generation of tourist brochures that include routing instructions and additional information presented in the form of so‐called detail lenses. The first contribution of this paper is the automatic creation of layouts for the brochures. Our approach is based on the minimization of an energy function that combines multiple goals: positioning of the lenses as close as possible to the corresponding region shown in an overview map, keeping the number of lenses low, and an efficient numbering of the lenses. The second contribution is a route‐aware simplification of the graph of streets used for traveling between the points of interest (POIs). This is done by reducing the graph consisting of all shortest paths through the minimization of an energy function. The output is a subset of street segments that enable traveling between all the POIs without considerable detours, while at the same time guaranteeing a clutter‐free visualization.  相似文献   
9.
The creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi-crystalline polymer in supercritical CO2 is demonstrated herein. The graft copolymer is synthesized by free radical polymerization of a vinyl monomer within the semi-crystalline polymer below its melt temperature. Such conditions afford selective grafting on the amorphous regions (block “B”) while leaving the crystalline domains (block “A”) unmodified. Accordingly, unique A-B, A-B-A, A-B-A-B-A, and so forth. block structures are formed. In this work, styrene is polymerized within polyamide 6, polyethylene terephthalate, and isotactic polypropylene. Purification of these material is performed to remove the un-grafted homopolymer, allowing for determination of the graft yield, the portion of polymer which covalently bonds to the semi-crystalline matrix. Grafting yields achieved in polyamide 6, polyethylene terephthalate, and isotactic polypropylene were 98%, 59%, and 15%, respectively. Property enhancements were observed upon further characterization of polystyrene-polyamide 6 copolymers, including high glass transition temperatures, the ability to be remelted, and tunable grafting molecular weight. Additionally, hydrophobicity is controlled by varying polystyrene composition. The remarkable range of accessed properties demonstrates this as a potential route to upcycling plastics.  相似文献   
10.
Failure modes of PDC cutters under different loads   总被引:3,自引:0,他引:3  
The capability of several types of flat PDC cutters to withstand combined loads were tested and evaluated by the impact and cutting of single PDC cutter on granite in a linear impact-cutting table.The primary failure modes of PDC cutters withstanding different combined loads were investigated and analyzed.The suggestions of enhancing PDC cutters to be suitable for drilling very hard rock have been made.  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