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   723篇
  免费   13篇
  国内免费   11篇
电工技术   4篇
化学工业   128篇
金属工艺   21篇
机械仪表   31篇
建筑科学   2篇
能源动力   18篇
轻工业   33篇
水利工程   2篇
石油天然气   4篇
无线电   98篇
一般工业技术   147篇
冶金工业   91篇
原子能技术   9篇
自动化技术   159篇
  2024年   2篇
  2023年   4篇
  2022年   14篇
  2021年   17篇
  2020年   14篇
  2019年   23篇
  2018年   24篇
  2017年   29篇
  2016年   25篇
  2015年   7篇
  2014年   21篇
  2013年   50篇
  2012年   22篇
  2011年   30篇
  2010年   28篇
  2009年   29篇
  2008年   22篇
  2007年   29篇
  2006年   18篇
  2005年   23篇
  2004年   20篇
  2003年   17篇
  2002年   20篇
  2001年   12篇
  2000年   19篇
  1999年   18篇
  1998年   32篇
  1997年   24篇
  1996年   20篇
  1995年   20篇
  1994年   15篇
  1993年   10篇
  1992年   8篇
  1991年   7篇
  1990年   7篇
  1989年   4篇
  1988年   8篇
  1987年   5篇
  1986年   3篇
  1985年   6篇
  1984年   5篇
  1983年   9篇
  1982年   2篇
  1980年   3篇
  1979年   4篇
  1978年   6篇
  1975年   2篇
  1972年   2篇
  1954年   1篇
  1952年   1篇
排序方式: 共有747条查询结果,搜索用时 15 毫秒
711.
This paper is concerned with the stability analysis of a linear system with interval time-varying delay using an augmented Lyapunov–Krasovskii (LK) functional approach. A delay-dependent stability criterion is developed in LMI framework to estimate the maximum allowable bound of the time-delay within which the system remains asymptotically stable in the sense of Lyapunov. Conservatism in the proposed delay-dependent stability analysis is reduced by introducing a new LK functional along with the Wirtinger's inequality and extended reciprocally convex matrix inequality. Finally, two numerical examples and the load frequency control problem have been solved to validate the superiority of the proposed stability criterion compared to existing literature.  相似文献   
712.
713.
Wireless Personal Communications - A major issue in VANETs is the high mobility of the nodes. Broadcasting helps in improving the performance of the VANETs in terms of secure routing. However,...  相似文献   
714.
Mungbean (Vigna radiata (L.) R. Wilczek var. radiata) is one of the most important pulse crops grown in South, East and Southeast Asia. It provides significant amounts of protein (240 g kg?1) and carbohydrate (630 g kg?1) and a range of micronutrients in diets. Mungbean protein and carbohydrate are easily digestible and create less flatulence than proteins derived from other legumes. In addition, mungbean is lower in phytic acid (72% of total phosphorus content) than pigeonpea (Cajanus cajan L. Millsp.), soybean (Glycine max L.) and cereals; phytic acid is commonly found in cereal and legume crops and has a negative impact on iron and zinc bioavailability in plant‐based diets. Owing to its palatable taste and nutritional quality, mungbean has been used as an iron‐rich whole food source for baby food. The wide genetic variability of mineral concentrations (e.g. 0.03–0.06 g Fe kg?1, 0.02–0.04 g Zn kg?1) in mungbean indicates possibilities to improve its micronutrient content through biofortification. Therefore biofortification of existing mungbean varieties has great potential for enhancing the nutritional quality of diets in South and Southeast Asia, where protein and micronutrient malnutrition are among the highest in the world. This review paper discusses the importance of mungbean in agricultural production and traditional diets and the potential of enhancing the nutritional quality of mungbean through breeding and other means, including agronomic practices. © 2013 Society of Chemical Industry  相似文献   
715.
Encapsulation of fish oil is an effective way to protect it against oxidation and masking its fishy odor. One of the possible ways to produce fish oil microcapsules is to produce an oil-in-water (O/W) emulsion followed by spray drying. This study compares the production of the O/W emulsion by mechanical homogenization (rotor–stator) with membrane emulsification and examines the effect of the type and amount of wall material added before drying. The membrane emulsification process selected for the emulsion production is premix membrane emulsification (ME), which consists of the production of a coarse emulsion by mechanical means followed by droplet breakup when the coarse emulsion is forced through a membrane. The emulsions produced had an oil load of 10 and 20 % and were stabilized using whey protein (isolate and hydrolyzate at 1 or 10 %) and sodium caseinate with concentrations of 2 and 10 %. Regarding the material used to build the microcapsule wall, whey protein, maltodextrin, or combinations of them were used at three different oil/wall ratios (1:1, 1:2, 1:3). The results clearly show that premix ME is a suitable technology for producing O/W emulsions stabilized with proteins, which have a smaller droplet size and are more monodisperse than those produced by rotor–stator emulsification. However, protein concentrations of 10 % are required to reduce the droplet size down to 2–3 μm. Small and monodisperse emulsions have been found to produce microcapsules with lower surface oil content, which increases oil encapsulation efficiency and presents lower levels of oxidation during storage at 30 °C. Of all the possible combinations studied, the one with the highest oil encapsulation efficiency is the production of a 20 % O/W emulsion stabilized with 10 % sodium caseinate followed by the addition of 50 % maltodextrin and drying.  相似文献   
716.
In this paper, we consider the problem of robust stability for a class of linear systems with interval time-varying delay under nonlinear perturbations using Lyapunov-Krasovskii (LK) functional approach. By partitioning the delay-interval into two segments of equal length, and evaluating the time-derivative of a candidate LK functional in each segment of the delay-interval, a less conservative delay-dependent stability criterion is developed to compute the maximum allowable bound for the delay-range within which the system under consideration remains asymptotically stable. In addition to the delay-bi-segmentation analysis procedure, the reduction in conservatism of the proposed delay-dependent stability criterion over recently reported results is also attributed to the fact that the time-derivative of the LK functional is bounded tightly using a newly proposed bounding condition without neglecting any useful terms in the delay-dependent stability analysis. The analysis, subsequently, yields a stable condition in convex linear matrix inequality (LMI) framework that can be solved non-conservatively at boundary conditions using standard numerical packages. Furthermore, as the number of decision variables involved in the proposed stability criterion is less, the criterion is computationally more effective. The effectiveness of the proposed stability criterion is validated through some standard numerical examples.  相似文献   
717.
This work reports the growth and characterization of thin films of Cu(In,Ga)Se2 (CIGS), which were grown by sequential sputtering, electrodeposition, and physical vapor deposition. Photovoltaic cells have been fabricated using these films with CdS heterojunction partners and the performance has been characterized. The effect of annealing conditions (temperature and duration) on the CIGS film microstructure and corresponding device performance has been investigated. Structure-property correlations were made using diffraction studies and Rietveld analysis. SEM studies were carried out to understand the effect of microstructure of the CIGS films on the solar cell efficiency. Cell efficiencies in excess of 10% have been achieved by using optimized annealing conditions. In addition, the optical properties of the sputtered CIGS films were characterized using variable angle spectroscopic ellipsometry and sputtered CIGS films were found to have optimum band gap.  相似文献   
718.
719.
This work describes the Site‐Specific System Simulator for Wireless System Design (S4W), a problem‐solving environment (PSE) that integrates visualization and computational tools with a high‐level graphical user interface. S4W improves the ability of wireless system engineers to design an indoor wireless system by encouraging them to think in terms of designing the system for optimal performance. Issues of computation management, data management, and location of resources are hidden from the user. The complex nature of data sets in the domain of wireless simulations calls for a customized set of visualization tools. Therefore, a number of ad hoc visualizations were developed for S4W. A study comparing the integrated system with an earlier, unintegrated version is presented. This helps to demonstrate the productivity gains that a PSE provides. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
720.
Summary The properties of guar seed oil (Cyammopsis Psoralioides) were studied, and it was found that it may be satisfactory for edible purposes. An interesting observation has been made that the unsaponifiable fraction of guar oil may be used as a stabilizer for oils.  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