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1.
企业并购申报制度诞生至今已经三十多年,但是关于其政策效应和制度设计的研究还非常缺乏。运用对53个国家或地区并购申报制度的调查数据,本文首次采用实证方法研究了并购申报制度的政策效应和机制选择问题。我们发现,并购申报制度的存在的确有助于促进市场竞争和提高经济绩效。而从不同申报机制的对比看,本文的一个重要发现是,目前采取自愿申报机制的国家或地区无论是从竞争效应还是经济效应来说,都优于采用强制申报机制的国家或地区。制度设计层面,无论是一国或地区的经济发展特征,还是政府执政效率,以及并购申报制度结构,都会影响到不同申报机制的选择概率。最后,综合实证研究结论,借鉴国际经验,我们提出了中国企业并购申报标准的设计方案,该方案已被国务院法制办采纳,成为《国务院关于经营者集中申报的规定(征求意见稿)》第三条对申报标准规定的主要内容。  相似文献   
2.
基于CT图像的人体股骨逆向工程研究   总被引:2,自引:1,他引:1  
股骨作为人体重要的组成骨骼有着重要的研究价值,应用逆向工程原理,通过阈值方法对采集于活人的股骨CT图像数据进行选取和边界识别,建立股骨不同扫描层的边界曲线并最终拟合成人体股骨模型.对该模型选取光滑系数进行后处理,得到较理想的三维模型,可以将模型导入后续有限元分析软件进行分析.  相似文献   
3.
阎永  王伟 《计算机仿真》2006,23(8):70-72,231
传统的小波收缩去噪算法采用单一的阈值,它没有考虑到小波系数的类聚性,图像中重要小波系数类聚的局部具有重要的奇异特性,应降低阈值以保留图像的边缘;反之含有不重要小波系数的局部应提高阈值以消除更多的噪声,因此该文提出了一种基于图像局域特性的小波收缩自适应阈值去噪算法,这种算法根据图像局部的奇异性大小,选择适当的阈值进行去噪。实验结果表明,相对于传统的单一阈值去噪算法来说,新的算法可使滤波后图像的峰值信噪比有所提高,在一定程度上克服了单一阈值去噪算法无法滤除高质量图像中噪声的缺陷。  相似文献   
4.
A test program was conducted to generate threshold and near-threshold data on two aluminum alloys: 2324-T39 and 7075-T7351, using compression pre-cracking constant-amplitude (CPCA) threshold testing procedures. Compact tension specimens were tested under stress ratios (R) of 0.1, 0.4, 0.7 or 0.8. Results were compared with either existing load-reduction data from the literature or with data that were generated using the load-reduction procedures. On the 2324 alloy, very little difference was observed between the load-reduction and CPCA test methods, although the CPCA test method consistently produced slightly lower thresholds or slightly faster crack-growth rates. But on the 2324 alloy, most of the load-reduction tests used extremely low initial ΔK values to grow the cracks under load reduction, which may explain the reason for the agreement. These low ΔK values were achieved by using compression pre-cracking to initiate a crack at the crack-starter notch. In contrast, the 7075 alloy showed very large differences between the CPCA and load-reduction results in the near-threshold and threshold regimes for R=0.1 and 0.4. Results under high R conditions (R=0.7) agreed very well between the two threshold test methods. An expression was also developed to generate fatigue-crack-growth-rate data using the CPCA threshold test method that would be unaffected by compressive yielding at the crack-starter notch and produce ‘steady-state’ constant-amplitude data in the near threshold regime.  相似文献   
5.
分割决策函数   总被引:1,自引:1,他引:0  
范策  陈意云 《计算机工程》2000,26(10):132-133
四叉树分解常常用在分形图象压缩中以获得变化的位比率。该文就可以改善图象质量和加速编码过程的分解决策函数而提出了熵(平均信息量)的概念。同时也讨论了其他分解决策函数,以及适宜的门限值所带来的优势。  相似文献   
6.
《Ergonomics》2012,55(13):1167-1199
A number of human—centred methodologies subjective, objective, and combined are used for slipperiness measurement. They comprise a variety of approaches from biomechanically-oriented experiments to psychophysical tests and subjective evaluations. The objective of this paper is to review some of the research done in the field, including such topics as awareness and perception of slipperiness, postural and balance control, rating scales for balance, adaptation to slippery conditions, measurement of unexpected movements, kinematics of slipping, and protective movements during falling. The role of human factors in slips and falls will be discussed. Strengths and weaknesses of human-centred approaches in relation to mechanical slip test methodologies are considered. Current friction-based criteria and thresholds for walking without slipping are reviewed for a number of work tasks. These include activities such as walking on a level or an inclined surface, running, stopping and jumping, as well as stair ascent and descent, manual exertion (pushing and pulling, load carrying, lifting) and particular concerns of the elderly and mobility disabled persons. Some future directions for slipperiness measurement and research in the field of slips and falls are outlined. Human-centred approaches for slipperiness measurement do have many applications. First, they are utilized to develop research hypotheses and models to predict workplace risks caused by slipping. Second, they are important alternatives to apparatus-based friction measurements and are used to validate such methodologies. Third, they are used as practical tools for evaluating and monitoring slip resistance properties of footwear, anti-skid devices and floor surfaces.  相似文献   
7.
一种新的自动多阈值图像分割方法   总被引:5,自引:0,他引:5  
王敏  骆惠  黄心汉 《信号处理》2000,16(1):90-94
本文提出了一种新的自动阈值图像分割方法.该方法选择二维灰度直方图的最佳一维投影作为输入信息,并利用了小波变换的多尺度特征分析此投影.在大尺度下抑制噪声并自动确定分割类数,在小尺度下精确定位阈值.实验表明新方法能够自动而快速地对图像进行分割而且有较强的抗干扰能力.  相似文献   
8.
针对355nm激光作用于熔石英光学元件后其损伤阈值容易变差的问题,提出使用1.7%纯HF溶液和0.4%HF与1.2%NH4F混合的BOE溶液对样品进行处理来提高它们的激光诱导损伤阈值(LIDT)。在相同的条件下将熔石英光学元件浸没到上述两种不同的刻蚀溶液中进行处理,通过测量刻蚀过程中元件重量变化来计算刻蚀速率,利用Zygo轮廓仪测试元件表面粗糙度,然后对355nm激光照射下熔石英元件的损伤阈值情况进行研究。损伤测试表明,LIDT与元件的材料去除深度有关系,用两种刻蚀液刻蚀去除一定深度后,LIDT均有增加,但是进一步去除会显著地降低元件的LIDT。在处理过程中,这两种刻蚀液的去除速率都很稳定,分别为85.9nm/min和58.6nm/min左右。另外,元件表面的粗糙度会随着刻蚀时间的增加而变大。在刻蚀过程中还通过纳米技术测量了熔石英元件表面的硬度及杨氏系数,不过没有证据表明其与激光诱导损伤有明确的关系。  相似文献   
9.
Medical image analysis is one of the major research areas in the last four decades. Many researchers have contributed quite good algorithms and reported results. In this paper, real coded genetic algorithm with Simulated Binary Crossover (SBX) based multilevel thresholding is used for the segmentation of medical brain images. The T2 weighted Magnetic Resonance Imaging (MRI) brain images are considered for image segmentation. The optimum multilevel thresholding is found by maximizing the entropy. The results are compared with the results of the existing algorithms like Nelder–Mead simplex, PSO, BF and ABF. The statistical performances of the 100 independent runs are reported. The results reveal that the performance of real coded genetic algorithm with SBX crossover based optimal multilevel thresholding for medical image is better and has consistent performance than already reported methods.  相似文献   
10.
Salt is commonly used in food processing and as a flavour enhancer. Dietary salt intake often exceeds the recommended levels and high intake is associated with several health concerns such as hypertension, cardiovascular disease and certain types of cancer. A systematic review of the literature was conducted to examine if individuals’ salt taste function and perception is associated with dietary intake. Interventional studies were excluded in order to investigate the taste-diet relationships of free-living individuals. The systematic literature search was conducted in five electronic databases and twenty articles that reported on salt taste function and perception, as well as dietary intake, were identified and included. Of these, eleven studies measured salt taste sensitivity as detection and/or recognition thresholds, seven measured salt taste intensity, and twelve assessed hedonic ratings (preference or liking). Based on the studies included in this review, salt taste sensitivity and intensity ratings were poorly associated with dietary intake. Hedonic ratings, on the other hand, were relatively more predictive of dietary intake. Considerable variations in the methods used in salt taste and dietary intake assessment were noted, which may explain the lack of taste-diet associations or inconsistent findings between studies. Although definitive conclusions cannot be drawn, this review suggests that a simple tool that assesses salt taste hedonic ratings may be a useful strategy to identify individuals who consume high levels of salt in a clinical setting and subsequently inform the selection of strategies to improve dietary salt intake in these individuals. Future studies investigating taste-diet relationship should emphasise high quality methodology and adequate statistical power for robust outcomes.  相似文献   
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