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   1615篇
  免费   54篇
  国内免费   2篇
电工技术   4篇
化学工业   222篇
金属工艺   7篇
机械仪表   19篇
建筑科学   58篇
矿业工程   1篇
能源动力   19篇
轻工业   168篇
水利工程   11篇
石油天然气   6篇
武器工业   2篇
无线电   82篇
一般工业技术   232篇
冶金工业   672篇
原子能技术   29篇
自动化技术   139篇
  2023年   6篇
  2022年   18篇
  2021年   27篇
  2020年   15篇
  2019年   21篇
  2018年   24篇
  2017年   20篇
  2016年   23篇
  2015年   15篇
  2014年   24篇
  2013年   81篇
  2012年   50篇
  2011年   78篇
  2010年   59篇
  2009年   63篇
  2008年   77篇
  2007年   64篇
  2006年   62篇
  2005年   47篇
  2004年   66篇
  2003年   50篇
  2002年   55篇
  2001年   29篇
  2000年   39篇
  1999年   46篇
  1998年   71篇
  1997年   50篇
  1996年   38篇
  1995年   41篇
  1994年   41篇
  1993年   31篇
  1992年   28篇
  1991年   14篇
  1990年   19篇
  1989年   25篇
  1988年   21篇
  1987年   23篇
  1986年   24篇
  1985年   16篇
  1984年   21篇
  1983年   18篇
  1982年   14篇
  1981年   15篇
  1980年   10篇
  1979年   16篇
  1978年   9篇
  1977年   12篇
  1976年   7篇
  1975年   10篇
  1968年   5篇
排序方式: 共有1671条查询结果,搜索用时 46 毫秒
61.
Supersaturated designs are factorial designs in which the number of factors exceeds the number of observations. Satterthwaite has suggested constructing such designs by a randomization procedure (random balance designs). In the present paper systematic designs are constructed which are, in a certain sense, m nearly orthogonal M possible. Examples of such designs are given constructed on an electronic computer and some properties of the designs are discussed.  相似文献   
62.
Abstract

This study of the use of photographs during the Paris Commune, and continuing through the periods of Bonapartism, Boulangism, Royalism, and the Dreyfus Affair, is excellent in every way but two, and neither shortcoming is the fault of the author. First, the price is unaccountably high considering that, secondly, the reproduction quality is so poor. Nevertheless, in this scholarly and lively text, students of photo history will find a thorough, well-documented, and very thoughtful examination of the use of photographs, and especially captioned photos, primarily by the various opponents to the Third Republic. This is not so much a discussion of important French photographers as an attempt to identify and interpret those often anonymous images that enjoyed national circulation from 1871–1914, and to analyse their use as propaganda. To do this, the author carefully traces their political and sociological context, examines prevailing notions about the nature of photographs, and comments about the effectiveness of various photographic propaganda campaigns (although he concedes that it is difficult to determine their absolute effect on 19th-century viewers).  相似文献   
63.
We present the special arterial fluid mechanics techniques we have developed for patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent. These techniques are used in conjunction with the core computational technique, which is the space?Ctime version of the variational multiscale (VMS) method and is called ??DST/SST-VMST.?? The special techniques include using NURBS for the spatial representation of the surface over which the stent mesh is built, mesh generation techniques for both the finite- and zero-thickness representations of the stent, techniques for generating refined layers of mesh near the arterial and stent surfaces, and models for representing double stent. We compute the unsteady flow patterns in the aneurysm and investigate how those patterns are influenced by the presence of single and double stents. We also compare the flow patterns obtained with the finite- and zero-thickness representations of the stent.  相似文献   
64.
Accurate reporting of sources of income is needed in studies of intergenerational transfers and welfare of the elderly. The objective of this paper is to investigate how memory in the elderly is related to the reporting of remittances received from their children in Thailand. Using data from a longitudinal study of 1036 persons age 60 to 93 in a province in Thailand, the influence of a word recall (verbal learning and recall), and nickname recall (verbal learning and recall) on reporting of remittance was assessed. Initially, both measures were positively and significantly related to the reporting of remittance. The results remained significant only for the nickname task after controlling for education, wealth, living arrangements and disability. The results highlight the importance of cognitive issues in the quality of data and the need for attention to memory in questionnaire design.  相似文献   
65.
Of concern to regulators and fire safety engineers is how flexible polyurethane foam drips and flows during burning. Specifically, flexible polyurethane foam forms a burning ‘pool’ of liquid as the foam decomposes, which can lead to accelerated flashover events. To fully study this phenomenon where the ‘pool fire’ accelerates heat release, large‐scale tests like the furniture calorimeter (American Society of Testing and Materials (ASTM) E1537) are used, and no small‐scale technique exists. In this paper, we present our work in developing a new sample holder that works with a bench‐scale heat release test, the cone calorimeter (ASTM E1354). The holder was built upon designs developed by the National Institute of Standards and Technology, which placed the foam in a cage in a vertical orientation during cone calorimeter testing. In this paper, we show the schematics for this test apparatus, as well as results obtained with this apparatus on four different flexible foams (shape memory and high‐density foam, flame retarded and non‐flame retarded). We compare the results from the vertical testing with that obtained via traditional horizontal ASTM E1354 testing. The advantages and disadvantages of this new apparatus are discussed in this paper. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
66.
Clean Technologies and Environmental Policy - Biochar application and enhanced weathering are negative emission technologies (NETs) with the potential for large-scale deployment for the removal of...  相似文献   
67.
68.
Wheat (Triticum aestivum L.) plays a central role in the health and nutrition of humans. Yet, little is known about possible flavor differences among different varieties. We have developed a model system using the house mouse (Mus musculus L.) to determine feeding preferences as a prelude to extending results to human sensory analysis. Here, we examine the application of a single‐elimination tournament design to the analysis of consumption preferences of a set of hard red and hard white spring wheat varieties. A single‐elimination tournament design in this case pairs 2 wheat varieties and only 1 of the 2 is advanced to further tests. Preferred varieties were advanced until an overall “winner” was identified; conversely, less desirable varieties were advanced such that an overall “loser” was identified. Hollis and IDO702 were the winner and loser, respectively, for the hard red varieties, and Clear White 515 and WA8123 were the winner and loser, respectively, for the hard white varieties. When using the more powerful protocol of 14 mice and a 4?d trial, differences in mean daily consumption preferences of 2 varieties were separated at P‐values as small as 2 × 10?8. The single‐elimination tournament design is an efficient means of identifying the most and least desirable varieties among a larger set of samples. One application for identifying the 2 extremes in preference within a group of varieties would be to use them as parents of a population to identify quantitative trait loci for preference.  相似文献   
69.
W.B. Yeats' restoration and recreation of Ballylee Castle in the west of Ireland from 1916 as ‘Thoor Ballylee’ saw it become the symbol and metaphor of his work as a poet. With the help of the architect, William Scott, an exponent of the English Arts and Crafts school, Yeats placed the tower and its landscape at the centre of his vision of the Irish past. The Arts and Crafts aesthetic that underpinned Yeats' idealisation of Irish society opposed and decried the modernisation of rural Ireland, attempting to preserve it as an idyll for the urban intelligentsia. In his appropriation and reconstruction of Ballylee Castle Yeats sought both to locate himself amongst the peasantry of the west of Ireland whom he idealised in his work and to reassert his own roots amongst the dying colonial order. This paper explores the ambivalence of Yeats' cultural nationalism against the backdrop of republican violence and the emergence of the Free State.  相似文献   
70.
Oil from the marine copepod, Calanus finmarchicus, which contains >86 % of fatty acids present as wax esters, is a novel source of n‐3 fatty acids for human consumption. In a randomized, two‐period crossover study, 18 healthy adults consumed 8 capsules providing 4 g of Calanus® Oil supplying a total of 260 mg EPA and 156 mg DHA primarily as wax esters, or 1 capsule of Lovaza® providing 465 mg EPA and 375 mg DHA as ethyl esters, each with an EPA‐ and DHA‐free breakfast. Plasma EPA and DHA were measured over a 72 h period (t = 1, 2, 4, 6, 8, 10, 12, 24, 48, and 72 h). The positive incremental area under the curve over the 72 h test period (iAUC0‐72 h) for both EPA and DHA was significantly different from zero (p < 0.0001) in both test conditions, with similar findings for the iAUC0–24 h and iAUC0–48 h, indicating the fatty acids were absorbed. There was no difference in the plasma iAUC0–72 h for EPA + DHA, or DHA individually, in response to Calanus Oil vs the ethyl ester condition; however, the iAUC0–48 h and iAUC0–72 h for plasma EPA in response to Calanus Oil were both significantly increased relative to the ethyl ester condition (iAUC0–48 h: 381 ± 31 vs 259 ± 39 μg*h/mL, p = 0.026; iAUC0‐72 h: 514 ± 47 vs 313 ± 49 μg*h/mL, p = 0.009). These data demonstrate a novel wax ester rich marine oil is a suitable alternative source of EPA and DHA for human consumption.  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