首页 | 官方网站   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   398篇
  免费   29篇
  国内免费   2篇
工业技术   429篇
  2021年   5篇
  2020年   5篇
  2019年   10篇
  2018年   9篇
  2017年   13篇
  2016年   9篇
  2015年   17篇
  2014年   13篇
  2013年   18篇
  2012年   33篇
  2011年   20篇
  2010年   17篇
  2009年   16篇
  2008年   11篇
  2007年   18篇
  2006年   20篇
  2005年   12篇
  2004年   11篇
  2003年   7篇
  2002年   5篇
  2001年   12篇
  2000年   2篇
  1999年   3篇
  1998年   25篇
  1997年   16篇
  1996年   14篇
  1995年   8篇
  1994年   3篇
  1993年   7篇
  1992年   5篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1988年   7篇
  1987年   4篇
  1986年   2篇
  1984年   4篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1977年   6篇
  1974年   4篇
  1972年   2篇
  1971年   2篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1967年   3篇
排序方式: 共有429条查询结果,搜索用时 421 毫秒
21.
In this paper, we propose a novel decision fusion algorithm for target tracking in forward-looking infrared image sequences recorded from an airborne platform. An important part of this study is identifying the failure modes in this type of imagery. Our strategy is to prevent these failure modes from developing into tracking failures. The results furnished by competing ego-motion compensation and tracking algorithms are evaluated based on their similarity to a target model constructed using the weighted composite reference function.  相似文献   
22.
This paper discusses a generalized method to measure with the electron probe microanalyzer (EPMA) the oxygen in a material containing a surface oxide layer. The continuum background is the most difficult to measure, particularly for materials in which oxygen-free samples cannot be produced. The method depends on the preparation of either oxygen-free samples or well characterized oxygen-containing samples. Specific application of the method to the Ti-Si-O system is discussed. In addition, measurements of oxide surface-layer thickness of 3.6–8.0 nm on Ti and Ti-Si compounds were obtained using EPMA and a scanning Auger microprobe (SAM). The nature of the oxide surface layers was shown using x-ray photoelectron spectroscopy (XPS).  相似文献   
23.
This paper proposes a qualitative assessment methodology that is comprised of a cluster analysis and an autoregression analysis that assess the effects of various road safety strategies implemented in Hong Kong over the last 10 years. The cluster analysis is first used to group over a hundred road safety projects and programs into a smaller set of meaningful road safety policy strategy clusters. These strategies, together with the trend factor, seasonal pattern, car crashworthiness and meteorological data are then used in the autoregression analysis to relate to the fatality and casualty rates of drivers, passengers, motorcyclists, and pedestrians. This method allows the evaluation of the overall effects of the road safety strategies, and the effects and relative significance of each individual strategy. The evaluation method is described, and the main findings of the study are discussed.  相似文献   
24.
The paper stressed the study not only of the relationships involving personality dimensions with driver behavior and performance in driving-related tasks, but also of the need to study these relationships in terms of primary personality dimensions or factors. The roles of the primary dimensions of impulsivity, sensation seeking and decision time from Eysenck's extroversion dimension were examined in relation to driver behavior and to the ability to perceive traffic signs. Similarly, the role of decision time in relation to field dependence was examined.  相似文献   
25.
This paper investigates the efficacy of the implementation of the conventional Proportional-Derivative (PD) controller and different Active Force Control (AFC) strategies to a 5-link biped robot through a series of simulation studies. The performance of the biped system is evaluated by making the biped walk on a horizontal flat surface, in which the locomotion is constrained within the sagittal plane. Initially, a classical PD controller has been used to control the biped robot. Then, a disturbance elimination method called Active Force Control (AFC) schemes has been incorporated. The effectiveness and robustness of the AFC as disturbance rejecter has been examined when a conventional crude approximation (AFCCA), and an intelligent active force control scheme, which is known as Active Force Control and Iterative Learning (AFCAIL) are employed. It is found that for both of the AFC control schemes proposed, the system is robust and stable even under the influence of disturbances. An attractive feature of the AFCAIL scheme is that inertia matrix tuning becomes much easier and automatic without any degradation in the performance.  相似文献   
26.
Ever since the 9/11 terrorist attack, many countries are considering the use of smart national identity card (SNIC) which has the ability to identify terrorists due to its biometric verification function. However, there are many ergonomics issues in the use of SNIC, e.g. card credibility. This research presents a case study survey of Malaysian users. Although most citizens (>96%) own MyKad (Malaysia SNIC), many do not carry it around and use its applications. This defeats one of its main purposes, i.e. combating terrorism. Thus, the research investigates ergonomics issues affecting the citizens’ Intention to Use (ITU) MyKad for homeland security by using an extended technology acceptance model. Five hundred questionnaires were collected and analysed using structural equation modelling. Results show that perceived credibility and performance expectancy are the key issues. The findings provide many countries with insights into methods of addressing ergonomics issues and increasing adoption of SNIC for homeland security.  相似文献   
27.
In this work, we study a liner shipping operational problem which considers how to dynamically determine the vessel speed and refueling decisions, for a single vessel in one service route. Our model is a multi-stage dynamic model, where the stochastic nature of the bunker prices is represented by a scenario tree structure. Also, we explicitly incorporate the uncertainty of bunker consumption rates into our model. As the model is a large-scale mixed integer programming model, we adopt a modified rolling horizon method to tackle the problem. Numerical results show that our framework provides a lower overall cost and more reliable schedule compared with the stationary model of a related work.  相似文献   
28.
We describe a system for the automatic acquisition and processing of digital images in a high-resolution X-ray microscope, including the formation of large-field high-resolution image montages. A computer-controlled sample positioning stage provides approximate coordinates for each high-resolution subimage. Individual subimages are corrected to compensate for time-varying, non-uniform illumination and CCD-related artefacts. They are then automatically assembled into a montage. The montage assembly algorithm is designed to use the overlap between each subimage and multiple neighbours to improve the performance of the registration step and the fidelity of the result. This is accomplished by explicit use of recorded stage positions, optimized ordering of subimage insertion, and registration of subimages to the developing montage. Using this procedure registration errors are below the resolution limit of the microscope (43 nm). The image produced is a seamless, large-field montage at full resolution, assembled automatically without human intervention. Beyond this, it is also an accurate X-ray transmission map that allows the quantitative measurement of anatomical and chemical features of the sample. Applying these tools to a biological problem, we have conducted the largest X-ray microscopical study to date.  相似文献   
29.
Trends in finger pinch strength in children, adults, and the elderly   总被引:2,自引:0,他引:2  
S N Imrhan  C H Loo 《Human factors》1989,31(6):689-701
This study explores empirical relationships among different types of pinches in three age groups. Peak maximum voluntary forces of several pinches--lateral, chuck, and pulp pinches with digits 2, 3, 4, and 5-were tested in 182 subjects comprising 62 children (5-12 years), 70 adults (18-40 years), and 50 elderly (60-89 years). Analysis of the forces indicated four groups of strength magnitude: (1) lateral and chuck, (2) pulp 2 and 3, (3) pulp 4, and (4) pulp 5, in that order; the strength of each type of pinch bears a definite quantitative relationship to every other type, regardless of age group or gender. The female-to-male strength ratio was greatest in children (89%) and least in adults (69%). Comparison with other pinch strength studies established that although force magnitudes may be strongly influenced by specific experimental conditions, empirical relationships among different pinch forces are fairly stable and predictable.  相似文献   
30.
We analyze in detail the requirements for the detailed physical modeling of nanoscale MOSFETs and show that Schro/spl uml/dinger drift-diffusion per subband simulations are adequate for the inverse modeling of bulk-Si MOSFETs with gate length down to 40 nm (channel length down to 26 nm) from their dc electrical characterization. We show that a proper treatment of quantum effects both in the channel and in the polysilicon gate through the direct solution of Schro/spl uml/dinger equation, and a transport model based on two-dimensional subbands are required for accurate and-after calibration-predictive modeling. The model is included in the NANOTCAD2D code (Curatola and Iannaccone, 2003). We also evaluate the performance gap to ballistic transport, by comparing the experiments with simulations based on a fully ballistic transport model on the devices structures extracted with the inverse modeling procedure.  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-23

京公网安备 11010802026262号