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   311篇
  免费   14篇
  国内免费   2篇
电工技术   10篇
综合类   2篇
化学工业   71篇
金属工艺   9篇
机械仪表   14篇
建筑科学   17篇
能源动力   21篇
轻工业   23篇
水利工程   1篇
石油天然气   1篇
无线电   40篇
一般工业技术   49篇
冶金工业   20篇
原子能技术   1篇
自动化技术   48篇
  2023年   5篇
  2022年   8篇
  2021年   12篇
  2020年   6篇
  2019年   8篇
  2018年   7篇
  2017年   7篇
  2016年   13篇
  2015年   11篇
  2014年   19篇
  2013年   42篇
  2012年   19篇
  2011年   37篇
  2010年   22篇
  2009年   19篇
  2008年   16篇
  2007年   12篇
  2006年   10篇
  2005年   5篇
  2004年   9篇
  2003年   4篇
  2002年   3篇
  2001年   4篇
  2000年   2篇
  1999年   3篇
  1998年   4篇
  1997年   1篇
  1996年   4篇
  1995年   4篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1986年   1篇
  1985年   3篇
  1983年   1篇
  1980年   1篇
排序方式: 共有327条查询结果,搜索用时 15 毫秒
71.
Frontiers of Information Technology & Electronic Engineering - Parameter estimation of the 2R-1C model is usually performed using iterative methods that require high-performance processing...  相似文献   
72.
Wireless Personal Communications - Medium access control protocols with common active period (AP MACs) are frequently used in wireless sensor networks (WSNs) with medium-load traffic requirements....  相似文献   
73.
The complete structure of an AGV control system is described in the first part of this paper. The AGV control system is hierarchical and consists of five levels. The structure of one level does not depend on the structures of the other levels. This means that the control system depends on the design of the AGV at the lowest level only, at the actuator servo-control level and its coordination in realizing AGV primitive functions.The second part of the paper describes rules applicable to AGV steering. The structure of these rules depends on two groups of factors. The first group is dependent on information groups fed to the AGV processor by the position sensor. The second group of factors represents aims and conditions and AGV steering such as positioning accuracy, positioning time, allowed room for maneuver, the shape of the given trajectory, etc. The AGV steering rules contain sequences of primitive functions. These primitive functions are of such types as “turn left”, “straighten” (correct), “go straight on”, etc. Trajectory, as one of the basic factors, is defined at the level of controlling an elementary movement. The term “to control an elementary movement” means to select a transport road throughout the transport network and to code it using “elementary movement” such as “go straight” (relating to road section), “turn left” (relating to turning at a crossroad) etc.The results of the AGV steering simulation are presented in the third part of the paper. An exact kinematic AGV model used for stimulating control models is also presented.  相似文献   
74.
This paper presents a cost-effective, non-intrusive technique of partially self-checking combinational circuits design. The proposed technique is similar to duplication with comparison, wherein duplicated function module and comparator act as a function checker that detects any erroneous response of the original function module. However, instead of realizing checker with full error-detection capability, we select a subset of erroneous responses to implement partial, but simplified function checker. A heuristic procedure that tries to find the optimal sum-of-product expression for partial function checker that minimizes its area while providing specified error coverage is described here. Effectiveness of the technique is evaluated on a set of MCNC 91 benchmark combinational circuits.  相似文献   
75.
The purpose of this study was to examine the effects of a total body strength-training program on changes in total and regional body composition, in particular intra-abdominal adipose tissue (IAAT), in older women. Fourteen healthy older women (mean age 67 +/- 1 yr) exercised 3 times/wk for 16 wk. Strength was assessed by one-repetition maximum tests, with training intensity gradually increased to approximately 67% of one repetition maximum. Body composition was measured by hydrodensitometry and regional body composition was measured by computed tomography. Strength was significantly increased in the upper (51%) and lower body (65%). There was no significant change in body weight (64.4 +/- 2.7 vs. 64.2 +/- 2.7 kg), total body fat (38.7 +/- 1.4 vs. 38.0 +/- 1.6%) or fat-free mass (39.7 +/- 1.0 vs. 40.0 +/- 0.9 kg). However, after ST, there were significant reductions in IAAT (143.9 +/- 13.3 vs. 130.0 +/- 12.4 cm2), the IAAT-to-subcutaneous adipose tissue ratio (0.48 +/- 0.04 vs. 0.44 +/- 0.04), and midthigh subcutaneous adipose tissue (141.7 +/- 11.5 vs. 133.6 +/- 10.8 cm2) and an increase in midthigh muscle (52.9 +/- 2.6 vs. 58.0 +/- 2.0 cm2) (all P < 0.05). In conclusion, significant reductions in IAAT and an increase in strength and muscle area were observed after a strength-training program in healthy older women. These changes may be important in preventing the negative health outcomes associated with the age-related increase in intra-abdominal obesity.  相似文献   
76.
A new technique to produce perfect bonding between GaAs dice and alumina substrates is reported. Utilizing this technique, void-free bondings have been achieved consistently. The quality of the bonded devices is confirmed by a Scanning Acoustic Microscope (SAM) having a spatial resolution of 25 μm. Thermal cycling between -25° C and 125° C, and thermal shock between -196° C and 135° C, have been used to assess the reliability of the specimens. The SAM was used to study the variation of the bonds in the tests. After the tests, the bonds show no sign of degradation and the GaAs dice did not crack. Shear test has also been performed. All the well bonded specimens passed the shear test. The shear strength correlated very well with the SAM images of the specimens taken before the test.  相似文献   
77.
Relatives of 88 clients enrolled in a postacute rehabilitation program for the treatment of traumatic brain injury completed Section 1 of the Katz Adjustment Scale (KAS-R1). The items were subjected to a principal component analysis, which yielded 10 statistically significant component groups. Internal consistency as determined by Cronbach alpha ranged from 0.78 to 0.94. Moderate correlations were observed between several component groups, suggesting some overlap in components derived. Results suggest that the 127 items of the KAS-R1 form component groups that may represent categorically differentiated behavioral symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
78.
Leptin has been hypothesized to play an important role in energy balance by affecting both energy intake and energy expenditure. The purpose of our study was to determine the relationship between fasting serum leptin concentrations and measures of energy expenditure in prepubertal children. We measured total energy expenditure (TEE; by the doubly labeled water technique), resting energy expenditure (REE; after an overnight fast), activity energy expenditure (AEE; TEE-REE), body composition (by dual energy x-ray absorptiometry), and fasting serum leptin concentration (by RIA) in 76 children. Simple correlations showed that all measures of energy expenditure (TEE, REE, and AEE) were positively related to the serum leptin concentration (r = 0.50, P < 0.001; r = 0.45, P < 0.001; and r = 0.30, P < 0.01, respectively). However, after adjusting for body composition (fat-free mass and fat mass), gender, and ethnicity, serum leptin concentrations were not related to any measure of energy expenditure (TEE, P = 0.61; REE, P = 0.97; AEE, P = 0.65). These latter findings were further confirmed using structural equation models with leptin and energy expenditure as dependent variables, and fat-free mass and fat mass as independent variables. Results from these models showed no direct effect of leptin and no indirect effect of fat mass (through leptin) on any measure of energy expenditure, when a path between fat mass and energy expenditure was present in the model. Thus, our data do not support the hypothesis that the serum leptin concentration (independent of fat mass) is related to measures of energy expenditure in children.  相似文献   
79.
Wireless Networks - Integrated process planning and scheduling in networked manufacturing systems plays a crucial role nowadays and in the forthcoming context of Industry 4.0 to enable effective...  相似文献   
80.
Support vector machines are arguably one of the most successful methods for data classification, but when using them in regression problems, literature suggests that their performance is no longer state-of-the-art. This paper compares performances of three machine learning methods for the prediction of independent output cutting parameters in a high speed turning process. Observed parameters were the surface roughness (Ra), cutting force \((F_{c})\), and tool lifetime (T). For the modelling, support vector regression (SVR), polynomial (quadratic) regression, and artificial neural network (ANN) were used. In this research, polynomial regression has outperformed SVR and ANN in the case of \(F_{c}\) and Ra prediction, while ANN had the best performance in the case of T, but also the worst performance in the case of \(F_{c}\) and Ra. The study has also shown that in SVR, the polynomial kernel has outperformed linear kernel and RBF kernel. In addition, there was no significant difference in performance between SVR and polynomial regression for prediction of all three output machining parameters.  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