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   327篇
  免费   10篇
  国内免费   1篇
电工技术   5篇
化学工业   75篇
金属工艺   4篇
机械仪表   2篇
建筑科学   9篇
能源动力   46篇
轻工业   38篇
石油天然气   2篇
无线电   17篇
一般工业技术   35篇
冶金工业   35篇
原子能技术   6篇
自动化技术   64篇
  2024年   1篇
  2023年   4篇
  2022年   9篇
  2021年   16篇
  2020年   5篇
  2019年   4篇
  2018年   9篇
  2017年   15篇
  2016年   10篇
  2015年   5篇
  2014年   13篇
  2013年   11篇
  2012年   13篇
  2011年   22篇
  2010年   26篇
  2009年   13篇
  2008年   16篇
  2007年   22篇
  2006年   10篇
  2005年   8篇
  2004年   6篇
  2003年   12篇
  2002年   11篇
  2001年   8篇
  2000年   5篇
  1999年   5篇
  1998年   12篇
  1997年   10篇
  1996年   6篇
  1995年   3篇
  1994年   4篇
  1993年   5篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
  1977年   1篇
  1976年   1篇
排序方式: 共有338条查询结果,搜索用时 78 毫秒
41.
42.
43.
Two studies examined sex differences in responsiveness of the hypothalamic-pituitary-adrenal cortical axis, a major component of the stress response. The first measured pituitary-adrenal responses to ovine corticotropin-releasing hormone (oCRH) in 24 healthy men and 19 healthy women. Plasma adrenocorticotropin hormone responses to oCRH were significantly greater among women than among men. In contrast, cortisol concentrations were similar in both groups, though elevations were more prolonged in women. Differences in corticotropin-releasing activity between men and women may help account for these findings; such differences in central components of the stress response might play a role in the known epidemiological differences in diseases of stress system dysregulation between men and women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
44.
Evaluated the effectiveness of the F and F-K indices of the MMPI in detecting dissimulation with 4 female and 80 male VA psychiatric patients applying for disability benefits. Four groups of Ss were identified that differed in terms of inferred motivation to exaggerate psychopathology so as to obtain benefits at desired levels. When psychopathology level and age were controlled, elevations of F and F-K indices coincided monotonically with conditions predicted to correspond with increasing motivation to dissimulate. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
45.
Cellular Non Linear Networks can be useful applied for the solution of several types of Partial Differential Equations (PDEs). This paper will describe an analogue circuit implementation for the simulation of one-dimensional Reaction-Diffusion PDE with the possibility to set different boundary conditions as well as to select different discretization methodologies. Fausto Sargeni was born in Riano (ROMA) in 1961. He received the Dipl. Eng. degree in Electronic Engineering at the University of Rome “La Sapienza" in 1987. In 1989 he jointed the Dept. of Electronic Engineering at the University of Rome “Tor Vergata" as Assistant Professor. In 1998 he became Associate Professor. His research interests include analog VLSI circuits for non linear circuits and high-speed interconnections. Vincenzo Bonaiuto was born in Rome, Italy, in 1962. He received the Dipl. Eng. degree in Electronic Engineering at the University of Rome “La Sapienza". In 1997 he received the the Ph.D. in Telecommunication and Microelectronics. In 1996 he jointed the Electronic Engineering Dept. as Assistant Professor at the University of Rome “Tor Vergata” and, in 2002, he became Associate Professor. His main research interests are in the area of non linear circuits, Artificial Neural Networks analogue/digital VLSI circuits implementation.  相似文献   
46.
Onshore and offshore wind farms require a high level of advanced maintenance. Supervisory control and data acquisition (SCADA) and condition monitoring systems are now being employed, generating large amounts of data. They require robust and flexible approaches to convert dataset into useful information. This paper presents a novel approach based on the correlations of SCADA variables to detect and identify faults and false alarms in wind turbines. A correlation matrix between all the SCADA variables is used for pattern recognition. A new method based on curve fittings is employed for detecting false alarms and abnormal behaviours or faults in the components. The study is done in a real case study, validated with false alarms.  相似文献   
47.
In this work, the ethanol steam reforming (ESR) reaction has been studied by using a dense Pd–Ag membrane reactor (MR) by varying the water/ethanol molar ratio between 3:1 and 9:1 in a temperature range of 300–400 °C and at 1.3 bar as reaction pressure. The MR was packed with a commercial Ru‐based catalyst and a constant sweep gas flow rate in counter current mode was used. The influence of the temperature and the feed molar ratio on different parameters such as the ethanol conversion, the hydrogen production, the hydrogen yield and the CO‐free hydrogen recovery has been evaluated.  相似文献   
48.
In the literature on logics of imperfect information it is often stated, incorrectly, that the Game-Theoretical Semantics of Independence-Friendly (IF) quantifiers captures the idea that the players of semantical games are forced to make some moves without knowledge of the moves of other players. We survey here the alternative semantics for IF logic that have been suggested in order to enforce this “epistemic reading” of sentences. We introduce some new proposals, and a more general logical language which distinguishes between “independence from actions” and “independence from strategies”. New semantics for IF logic can be obtained by choosing embeddings of the set of IF sentences into this larger language. We compare all the semantics proposed and their purported game-theoretical justifications, and disprove a few claims that have been made in the literature.  相似文献   
49.
The microhardness–nanostructure correlation of a series of silica/silicon oxycarbide porous composites has been investigated, as a function of pyrolysis temperature, T p. The pyrolyzed products have been studied by means of scanning electron microscopy, mercury porosimetry, chemical analysis, solid-state 29Si-NMR, X-ray diffraction, Raman spectroscopy, and microindentation hardness. Two distinct regimes are found for the microhardness behavior with T p. In the low-temperature regime (1000°C ≤ T p < 1300°C), the material response to indentation seems to be dominated by the large amount of pores present in the samples. In this T p range, low microhardness values, H , are found (<110 MPa). Above T p= 1300°C, a conspicuous H increase is observed. In this high-temperature regime ( T p= 1300–1500°C), microhardness values are shown to notably increase with increasing pyrolysis temperature. The H behavior at T p= 1300–1500°C is discussed in terms of (i) the volume fraction of pores and the average pore size, (ii) the bond density of the oxycarbide network, and (iii) the occurrence of a nanocrystalline SiC phase.  相似文献   
50.
Auto-thermal reforming (ATR), a combination of exothermic partial oxidation and endothermic steam reforming of methane, is an important process to produce syngas for petrochemical industries. In a commercial ATR unit, tubular fixed bed reactors are typically used. Pressure drop across the tube, high manufacturing costs, and low production capacity are some disadvantages of these reactors. The main propose of this study is to offer an optimized radial flow, spherical packed bed reactor as a promising alternative for overcoming the drawbacks of conventional tubular reactors. In the current research, a one dimensional pseudo-homogeneous model based on mass, energy, and momentum balances is applied to simulate the performance of packed-bed reactors for the production of syngas in both tubular and spherical reactors. In the optimization section, the proposed work explores optimal values of various decision variables that simultaneously maximize outlet molar flow rate of H2, CO and minimize molar flow rate of CO2 from novel spherical reactor. The multi-objective model is transformed to a single objective optimization problem by weighted sum method and the single optimum point is found by using genetic algorithm. The optimization results show that the pressure drop in the spherical reactor is negligible in comparison to that of the conventional tubular reactor. Therefore, it is inferred that the spherical reactor can operate with much higher feed flow rate, more catalyst loading, and smaller catalyst particles.  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