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   216篇
  免费   14篇
  国内免费   1篇
电工技术   1篇
化学工业   65篇
金属工艺   2篇
机械仪表   4篇
建筑科学   5篇
能源动力   8篇
轻工业   63篇
水利工程   1篇
石油天然气   1篇
无线电   8篇
一般工业技术   31篇
冶金工业   13篇
原子能技术   1篇
自动化技术   28篇
  2024年   1篇
  2023年   4篇
  2022年   16篇
  2021年   7篇
  2020年   7篇
  2019年   9篇
  2018年   8篇
  2017年   5篇
  2016年   14篇
  2015年   3篇
  2014年   12篇
  2013年   14篇
  2012年   16篇
  2011年   22篇
  2010年   9篇
  2009年   4篇
  2008年   5篇
  2007年   10篇
  2006年   5篇
  2005年   11篇
  2004年   7篇
  2003年   10篇
  2002年   6篇
  2001年   2篇
  2000年   4篇
  1998年   5篇
  1997年   1篇
  1996年   2篇
  1994年   2篇
  1993年   2篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1975年   1篇
  1973年   1篇
  1961年   1篇
  1957年   1篇
排序方式: 共有231条查询结果,搜索用时 15 毫秒
131.
Mo/TiO2 catalysts were modified with Nb by two different methods, sol–gel and surface deposition, in order to study the effect of Nb incorporation on the thiophene HDS activity. The results show that the formation of Nb–Ti mixed oxides leads to catalysts with poor HDS activity while the deposition of Nb oxide species on the surface of TiO2 leads to catalysts with activities larger than those of Mo/Al2O3 and Mo/TiO2. This increase in activity was attributed to the formation of a larger population of Mo sulfur anionic vacancies when Nb was surface deposited on the TiO2.  相似文献   
132.
Tequila is elaborated from Agave tequilana Weber blue variety and it is commercialized at different stages of aging. Chemical composition of this product has often been addressed; however, data on phenolic compounds are scarce. In this work, a high-performance liquid chromatography–electrospray ionization-ion trap mass spectrometry (HPLC–ESI-ITMS) procedure has been established for the determination of 34 small phenolic compounds. The combination of suitable separation conditions with extraction of chromatograms at individual m/z values has enabled for total analysis run of 17 min (11 min separation plus 6 min column cleaning/equilibration) with the detection limits in the range 1.28–75.0 μg l?1 (0.07–6.1 pmol on-column). Commercial tequilas analyzed included 6 white, 12 rested, and 4 aged. The following acids were found and quantified: gallic, procatechuic, 4-hydroxybenzoic, vanillic, syringic, homovanillic, 3-hydroxybenzoic, ferulic, salicylic, and benzoic. The white tequilas contained fewer compounds and lower total phenolics concentrations (range 36–408 μg l?1) as compared to the rested and aged liquors (515–4,296 and 2,048–3,249 μg l?1, respectively). In the latter products, syringic, vanillic, procatechuic, and gallic acids were the most abundant, which indicates that maturation in wooden barrels is the main source of small phenolics in tequila. On the other part, homovanillic acid was found in all tequila types (medians for white, rested, and aged products 82, 153, and 162 μg l?1, respectively), suggesting that some phenolics may originate from the raw material or might be formed during liquor elaboration.  相似文献   
133.
Oncolytic adenoviruses are promising new anticancer agents. To realize their full anticancer potential, they are being engineered to express therapeutic payloads. Tumor suppressor p53 function contributes to oncolytic adenovirus activity. Many cancer cells carry an intact TP53 gene but express p53 inhibitors that compromise p53 function. Therefore, we hypothesized that oncolytic adenoviruses could be made more effective by suppressing p53 inhibitors in selected cancer cells. To investigate this concept, we attenuated the expression of the established p53 inhibitor synoviolin (SYVN1) in A549 lung cancer cells by RNA interference. Silencing SYVN1 inhibited p53 degradation, thereby increasing p53 activity, and promoted adenovirus-induced A549 cell death. Based on these observations, we constructed a new oncolytic adenovirus that expresses a short hairpin RNA against SYVN1. This virus killed A549 cells more effectively in vitro and inhibited A549 xenograft tumor growth in vivo. Surprisingly, increased susceptibility to adenovirus-mediated cell killing by SYVN1 silencing was also observed in A549 TP53 knockout cells. Hence, while the mechanism of SYVN1-mediated inhibition of adenovirus replication is not fully understood, our results clearly show that RNA interference technology can be exploited to design more potent oncolytic adenoviruses.  相似文献   
134.
This paper is motivated by the interest in finding significant movements in financial stock prices. However, when the number of profitable opportunities is scarce, the prediction of these cases is difficult. In a previous work, we have introduced evolving decision rules (EDR) to detect financial opportunities. The objective of EDR is to classify the minority class (positive eases) in imbalaneed environments. EDR provides a range of classifications to find the best balance between not making mistakes and not missing opportunities. The goals of this paper are: 1) to show that EDR produces a range of solutions to suit the investor's preferences and 2) to analyze the factors that benefit the performance of EDR. A series of experiments was performed. EDR was tested using a data set from the London Financial Market. To analyze the EDR behaviour, another experiment was carried out using three artificial data sets, whose solutions have different levels of complexity. Finally, an illustrative example was provided to show how a bigger collection of rules is able to classify more positive eases in imbalanced data sets. Experimental results show that: 1) EDR offers a range of solutions to fit the risk guidelines of different types of investors, and 2) a bigger collection of rules is able to classify more positive eases in imbalanced environments.  相似文献   
135.
This paper is concerned with the design of an LMI‐based discrete‐time nonlinear state observer for an anaerobic digestion model. In presence of disturbances in both the dynamics of the model and the output measurement signals, the proposed observer robustly estimates all state variables including bacteria concentrations, which are costly and difficult to measure. In the goal to increase applicability of the proposed observer for other systems, we present the theoretical results in a general way. First, due to the use of Young's inequality in a convenient way, we get new sufficient conditions, expressed in terms of bilinear matrix inequalities (BMIs), ensuring the criterion. Then, to render the BMIs convex, two alternative solutions are proposed, where both lead to linear matrix inequality (LMI) conditions. It is shown analytically and numerically that these two solutions provide less conservative LMI conditions compared to the existing methods in the literature. To validate the proposed methodology on a real‐world model, an application to an anaerobic digestion model is given.  相似文献   
136.
137.
138.
The aim of this study is to show the investigation effects of environmental and operating factors on photovoltaic (PV) panel efficiency using by multivariate linear regression. Also in this study, the relationship between PV panel efficiency and some environmental and operating factors (solar radiation, open‐circuit voltage, short circuit current (Isc), power, fill factor, outside temperature, humidity, wind speed, and voltage) were investigated using multivariate linear regression. The effect of binary parameter interactions on panel performance was investigated using the backward elimination (or deletion) method. The data used in the analysis were obtained from monocrystal and polycrystal panels in December in the winter season. In all analyzes, the regression values are close to 1, which indicates that the compatibility between binary parameters and performance characteristics is perfect. In addition, the three most effective parameters on panel efficiency were found to be solar radiation, maximum power (Pmax), and Isc, respectively.  相似文献   
139.
140.
Use of low degree of hydrolysis (DH < 10%) with enzymatic treatment can produce protein hydrolysates with functional properties superior to the raw material. Suspensions of Phaseolus lunatus protein isolate (PPI) were treated with one of two commercial enzymes (Alcalase or Flavourzyme) at 50 °C and pH 8.0. DH with Alcalase was greater than Flavourzyme at 5 or 15 min of reaction. Alcalase-prepared hydrolysates had more peptides than those prepared with Flavourzyme. All the hydrolysates had higher solubility than the PPI, the highest being for the Alcalase-prepared hydrolysate at 15 min reaction time. Overall, the Alcalase-prepared hydrolysates had better solubility characteristics, whereas the Flavourzyme-prepared hydrolysates had better film properties (maximum emulsifying capacity and the highest foam formation values). This is probably because of the greater ease of movement toward the interface as shown by their high surface hydrophobicity values. The Alcalase-prepared hydrolysates had generally low or nonexistent film properties.  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