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   48篇
  免费   3篇
  国内免费   1篇
化学工业   15篇
金属工艺   1篇
能源动力   1篇
轻工业   3篇
水利工程   2篇
石油天然气   1篇
无线电   3篇
一般工业技术   8篇
冶金工业   8篇
原子能技术   1篇
自动化技术   9篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2015年   2篇
  2014年   1篇
  2013年   3篇
  2012年   2篇
  2011年   3篇
  2010年   4篇
  2009年   4篇
  2008年   3篇
  2007年   2篇
  2006年   6篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2001年   1篇
  1999年   1篇
  1997年   1篇
  1993年   3篇
  1992年   3篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1982年   1篇
排序方式: 共有52条查询结果,搜索用时 109 毫秒
1.
This study adopted a systemic approach to studying intervention efforts with delinquent youth, examining the association between several youth corrections programs and adult criminal outcomes. Two studies were designed to use juvenile and adult court records to evaluate the effectiveness of treatment programs provided to delinquent youth in state custody. The results of Study 1 suggested that court-recorded delinquent charges can be used to estimate delinquency severity. The results of Study 2 presented a discouraging but not entirely unexpected illustration of the effectiveness of intervention efforts among delinquent youth. It was found that time spent in juvenile detention facilities, work programs, and group homes was associated with negative adult criminal outcomes. No links between time spent in youth corrections programs and positive outcomes were identified. Implications for future program evaluation efforts are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
2.
Nestor is a real-time recognition and camera pose estimation system for planar shapes. The system allows shapes that carry contextual meanings for humans to be used as Augmented Reality (AR) tracking targets. The user can teach the system new shapes in real time. New shapes can be shown to the system frontally, or they can be automatically rectified according to previously learned shapes. Shapes can be automatically assigned virtual content by classification according to a shape class library. Nestor performs shape recognition by analyzing contour structures and generating projective-invariant signatures from their concavities. The concavities are further used to extract features for pose estimation and tracking. Pose refinement is carried out by minimizing the reprojection error between sample points on each image contour and its library counterpart. Sample points are matched by evolving an active contour in real time. Our experiments show that the system provides stable and accurate registration, and runs at interactive frame rates on a Nokia N95 mobile phone.  相似文献   
3.
Instructors in higher education are disseminating instructional content via podcasting, as many rally behind the technology’s potential benefits. Others have expressed concern about the risks of deleterious effects that might accompany the adoption of podcasting, such as lower class attendance. Yet, relatively few studies have investigated students’ perceptions of podcasting for educational purposes, especially in relation to different podcasting forms: repetitive and supplemental. The present study explored students’ readiness and attitudes towards these two forms of podcasting to provide fundamental information for future researchers and educators. The results indicated that students may not be as ready or eager to use podcasting for repetitive or supplemental educational purposes as much as we think they are, but they could be persuaded.  相似文献   
4.
Taking tests enhances learning. But what happens when one cannot answer a test question—does an unsuccessful retrieval attempt impede future learning or enhance it? The authors examined this question using materials that ensured that retrieval attempts would be unsuccessful. In Experiments 1 and 2, participants were asked fictional general-knowledge questions (e.g., “What peace treaty ended the Calumet War?”). In Experiments 3–6, participants were shown a cue word (e.g., whale) and were asked to guess a weak associate (e.g., mammal); the rare trials on which participants guessed the correct response were excluded from the analyses. In the test condition, participants attempted to answer the question before being shown the answer; in the read-only condition, the question and answer were presented together. Unsuccessful retrieval attempts enhanced learning with both types of materials. These results demonstrate that retrieval attempts enhance future learning; they also suggest that taking challenging tests—instead of avoiding errors—may be one key to effective learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
Hexavalent chromium (Cr6+) emission from stainless steel welding operations poses a serious threat to worker safety and ambient air quality. In this study, tetraethyloxysilane (TEOS) was used as a silica precursor additive to welding shield gas during gas tungsten arc welding (GTAW) operations to determine the feasibility of using these chemicals for Cr6+ exposure reduction. Fume aerosol samples were analyzed for Cr6+ concentration using ion chromatography (IC) and for total Cr by inductively coupled plasma with atomic emission spectroscopy (ICP-AES).At high temperature, silica precursors are pyrolyzed to form amorphous silica (SiO2) which can condense on the existing metal aerosols. The inert silica layer surrounding the aerosols can prevent further chromium oxidation by insulating chromium aerosols. Experimental results showed approximately 45% Cr6+ reductions when 3.0% TEOS was added to the shield gas. Nitrate concentration also decreased by 53%, indicating that reactive oxygen species were also reduced. Transmission electron microscopy (TEM) images of collected fume aerosols showed SiO2 coating on metal particles, verifying the proposed mechanism.  相似文献   
6.
Polarization-sensitive optical coherence tomography provides high-resolution cross-sectional characterization of birefringence in turbid media. Weakly birefringent biological tissues such as the retinal nerve fiber layer (RNFL) require advanced speckle noise reduction for high-sensitivity measurement of form birefringence. We present a novel method for high-sensitivity birefringence quantification by using enhanced polarization-sensitive optical coherence tomography (EPS-OCT) and introduce the polarimetric signal-to-noise ratio, a mathematical tool for analyzing speckle noise in polarimetry. Multiple incident polarization states and non-linear fitting of normalized Stokes vectors allow determination of retardation with +/-1 degrees uncertainty with invariance to unknown unitary polarization transformations. Results from a weakly birefringent turbid film and in vivo primate RNFL are presented. In addition, we discuss the potential of EPS-OCT for noninvasive quantification of intracellular filamentous nanostructures, such as neurotubules in the RNFL that are lost during the progression of glaucoma.  相似文献   
7.
Summary We investigate the extent to which it may be possible to carry out a regression analysis using graphics alone, an idea that we refer to asgraphical regression. The limitations of this idea are explored. It is shown that graphical regression is theoretically possible with essentially no constraints on the conditional distribution of the response given the predictors, but with some conditions on marginal distribution of the predictors. Dimension reduction subspaces and added variable plots play a central role in the development. The possibility of useful methodology is explored through two examples. Read before the Spanish Statistical Society at a meeting organized by the Carlos III University of Madrid on Wednesday, April 21, 1993  相似文献   
8.
This study examined the factors influencing water-based recreationists' perceptions of support and opposition towards off-shore wind energy development (OWD) on Lake Erie. Much of the proposed or future Lake Erie OWD infrastructure may either be within or adjacent to public lands, waters, and protected areas, raising concerns about the potential environmental and social impacts upon recreation stakeholders. The limited body of OWD research within the United States has suggested there are numerous factors that may influence overall perceptions of support and opposition such as political orientation and beliefs in climate change. Moreover, recent research has proposed that the perceived recreation impact of OWD may be the most important predictor of support and opposition. This study confirmed this premise and found the perceived recreation impact of OWD to be the strongest predictor of support. Results of a multiple linear regression suggested that political orientation (β?=?0.135), beliefs in the anthropogenic causation of climate change (β?=?0.207), beliefs in the occurrence of climate change (β?=?0.213), and the perceived recreation impact of OWD among water-based recreationists (β?=?0.439) were significant predictors of support for OWD on Lake Erie (R2?=?0.46). Study findings corroborated previous research which suggested that regional climate change beliefs and political attitudes may influence support for OWD. From a policy and management standpoint, study results highlight the importance of assessing and communicating recreation experience and use impacts when planning, developing, and managing OWD and related decisions in the United States.  相似文献   
9.
Techniques for three-dimensional (3D) light microscopy of a wide variety of biological specimens are rapidly maturing. The next advances are to improve image contrast, make image resolution as isotropic as possible, and perform quantitative analysis. This article discusses methods of automatic image analysis and blind deconvolution to compensate for the microscope's point-spread function (impulse response). Special emphasis is given to quantitative analysis based on adaptive segmentation, the results of which can be used to quantify and trace individual structures, and to montage high-resolution fields as well as the results of image analysis on these fields into a wide-area view with an associated computer database representation. We exploit the specific advantages accruing from the 3D nature of the data to achieve new capabilities not possible with 2D imaging. Fundamental and practical challenges in this area and our progress to date including automated segmentation, cell counting, neuron tracing, mosaic synthesis, “blind” deconvolution of large 3D images, and high-speed computation are presented. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 240–254, 1997  相似文献   
10.
The dynamic behavior of sandwich composites made of E-Glass Vinyl-Ester (EVE) facesheets and graded Corecell™ A-series foam was studied using a shock tube apparatus. The foam core was monotonically graded based on increasing acoustic wave impedance, with the foam core layer of lowest wave impedance facing the blast. The specimen dimensions were held constant for all core configurations, while the number of core layers varied, resulting in specimens with one layer, two layer, three layer, and four layers of foam core gradation. Prior to shock tube testing, the quasi-static and dynamic constitutive behavior (compressive) of each type of foam was evaluated. During the shock tube testing, high-speed photography coupled with the optical technique of Digital Image Correlation (DIC) was utilized to capture the real-time deformation process as well as mechanisms of failure. Post-mortem analysis was also carried out to evaluate the overall blast performance of these configurations. The results indicated that increasing the number of monotonically graded foam core layers, thus reducing the acoustic wave impedance mismatch between successive layers, helped maintain structural integrity and increased the blast performance of the sandwich composite.  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