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   1260篇
  免费   144篇
  国内免费   1篇
电工技术   23篇
化学工业   405篇
金属工艺   63篇
机械仪表   35篇
建筑科学   28篇
矿业工程   5篇
能源动力   42篇
轻工业   202篇
水利工程   11篇
石油天然气   5篇
无线电   55篇
一般工业技术   309篇
冶金工业   23篇
原子能技术   18篇
自动化技术   181篇
  2023年   14篇
  2022年   11篇
  2021年   48篇
  2020年   39篇
  2019年   44篇
  2018年   66篇
  2017年   55篇
  2016年   55篇
  2015年   75篇
  2014年   100篇
  2013年   221篇
  2012年   67篇
  2011年   62篇
  2010年   76篇
  2009年   60篇
  2008年   30篇
  2007年   18篇
  2006年   23篇
  2005年   10篇
  2004年   14篇
  2003年   9篇
  2002年   8篇
  2001年   16篇
  2000年   20篇
  1999年   8篇
  1998年   9篇
  1997年   12篇
  1996年   13篇
  1995年   11篇
  1994年   10篇
  1993年   13篇
  1992年   9篇
  1991年   11篇
  1990年   6篇
  1989年   6篇
  1988年   8篇
  1987年   7篇
  1986年   9篇
  1985年   12篇
  1984年   12篇
  1983年   15篇
  1982年   8篇
  1981年   18篇
  1980年   7篇
  1979年   6篇
  1977年   6篇
  1976年   8篇
  1975年   7篇
  1974年   9篇
  1973年   5篇
排序方式: 共有1405条查询结果,搜索用时 31 毫秒
51.
This paper represents the elements and the use of the upgraded simulation system, developed in the last half decade for ?tore Steel billet caster. The simulation system is used in the context of the state-of-the-art automation and information of the twenty-five year-old three-strand Concast billet continuous caster for dimensions square 140 and 180 mm with the capacity of 160,000 tons/year. The simulation system is used in the off-line and on-line modes. The off-line mode is used in order to set the proper process parameters and to calculate the temperature field, macrosegregation, and grain structure of the strand. It is also used to calculate the changes in the caster design such as the secondary cooling and the position of the SEN. The on-line model is used in automatic casting control system. The paper represents an update of our BHM publication of 2005 (Application of Continous Casting Simulation at ?tore Steel, BHM, Vol. 150, No. 9, 300–306).  相似文献   
52.
Hydrogenation of prochiral ketones using chiral transition-metal catalysts represents the cleanest way to access enantiomerically enriched secondary alcohols, which are important building blocks in fine chemicals synthesis. Despite excellent activity, selectivity and compatibility of metal complexes with variety of functional groups, no universal catalysts exist. In this article we summarize the advances in catalyst systems for the asymmetric homogenous and heterogenous hydrogenation of ketones that have been made in past decade. The development of catalysts is oriented in reaching as high as activity with low catalyst loadings, using “greener’’ conditions, and ensuring good recyclability of catalysts. Even though ruthenium complexes represent the largest part of the catalysts, other metals rapidly penetrate this field.  相似文献   
53.
We present a sensitivity analysis-based method for explaining prediction models that can be applied to any type of classification or regression model. Its advantage over existing general methods is that all subsets of input features are perturbed, so interactions and redundancies between features are taken into account. Furthermore, when explaining an additive model, the method is equivalent to commonly used additive model-specific methods. We illustrate the method’s usefulness with examples from artificial and real-world data sets and an empirical analysis of running times. Results from a controlled experiment with 122 participants suggest that the method’s explanations improved the participants’ understanding of the model.  相似文献   
54.
In this work, we will introduce the notion of connective stability in the mean for large-scale stochastic systems under structural perturbations. Sufficient conditions for this kind of stability are obtained by the decomposition-aggregation method in the context of vector Liapuiiov functions.  相似文献   
55.
The production process of mineral wool is affected by several constantly changing factors. The ingredients for the mineral wool are melted in a furnace. The molten mineral charge exits the bottom of the furnace in a water-cooled trough and falls into a fiberization device (the centrifuge). The centrifuge forms the fibers. At this stage binders are injected to bind the fibers together. To ensure the quality of the end product (the consistent thickness) the flow of the bounded fibers must be as constant as possible. One way to ensure that is to control the speed of the conveyor belt that transports the bounded fibers from the centrifuge to the curing process. Predictive functional controller and PID controller are considered to replace an existing algorithm. Both can easily replace an existing one as they do not require any new sensor installation. All three algorithms are presented and tested on a developed plant model. The study showed that the predictive control gives better results than the existing and PID controller.  相似文献   
56.
57.
Abstract

The paper describes the possibility of using the speckle pattern decorrelation for determination of small deformation tensor components of an elementary object surface area in an optical image field. The relationship between the small-deformation tensor and the speckle field displacement is analysed in detail. The studied problem is presented from the approximation viewpoint of both wave and geometrical optics.  相似文献   
58.
The pin power density distribution in reactor is an important quantity, necessary for the adequate assessment of fuel conditions and of core structures and pressure vessel radiation embrittlement as well.The paper shows the detailed comparison of calculated and experimentally determined pin by pin power distribution. To verify the reliability of measured data used for comparison with calculated data, the symmetrically located pins were measured. The calculations have been done with deterministic and Monte Carlo approach. The effect of different data libraries used for calculations are discussed as well.  相似文献   
59.
Potential beneficial components, including proteins, total phenolics, total flavonoids, carotenoids, tocopherols, and DPPH radical scavenging activity, were investigated in wholemeal of ten bread (T. aestivum L.) and ten durum (T. durum Desf.) novel wheat genotypes. In addition, the activity rate of lipoxygenase (LOX) and peroxidase (POD) enzymes implicated in the antioxidant metabolism was determined. The protein contnet and the antioxidant properties varied according to the two different wheat species, as well as, between the different bread and durum wheat genotypes themselves. The results indicated significant differences in proteins and antioxidant compounds between bread and durum wheat. Higher total proteins, wet gluten and antioxidants contents, combined with lower LOX and POD activities, point to a higher nutritive value of durum wheat than bread wheat.  相似文献   
60.
A multiscale approach spanning from the segmental (subnanometer) up to micrometer level was applied for detailed study of the self‐assembly of aliphatic block polyurethane (PU) elastomers. To understand the principles of the self‐organization of hard and soft segments in the complex multi‐component systems, several two‐component model PU samples, that is, the products of 1,6‐diisocyanatohexane (HDI) with three diols differing in the length and constitution were also prepared, characterized, and investigated: (i) polycarbonate‐based macrodiol (MD), (ii) biodegradable oligomeric diol (DL‐L; product of butane‐1,4‐diol and D,L‐lactide), and (iii) butane‐1,4‐diol (BD). The study (particularly 13C‐1H PILGRIM NMR spectra) reveals complex internal organization and interesting (application appealing) behavior of multi‐component PUs. Hard segments (HDI+BD products) feature self‐assembled and significantly folded chain conformations with interdomain spacing 15–22 nm (small‐angle X‐ray scattering analysis). The small domains are hierarchically assembled in various structural formations of µm size (spherulites) depending on PU composition, as detected by transmission electron microscopy and atomic force microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41590.  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