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   100篇
  免费   2篇
工业技术   102篇
  2023年   1篇
  2021年   2篇
  2020年   1篇
  2019年   5篇
  2018年   2篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   4篇
  2013年   9篇
  2012年   3篇
  2011年   3篇
  2010年   2篇
  2009年   4篇
  2008年   5篇
  2007年   7篇
  2006年   1篇
  2005年   2篇
  2004年   7篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   8篇
  1997年   3篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1976年   2篇
  1975年   2篇
  1972年   1篇
  1971年   1篇
排序方式: 共有102条查询结果,搜索用时 93 毫秒
1.
An apparatus for investigating pulsed turbulent liquid flow in a 2 in. diameter, 80 ft. pipeline is described. The pulsation unit was powered by compressed air with a consumption of up to 2.7 std. cu.ft./min. at 35 lb/in2 gauge. The pressure drop for water flowing at mean velocities of 7.66 to 12.28 ft./sec. has been measured, both for steady flow and for pulsed flow, at frequencies between 0.48 and 0.82 Hz. The experimentally measured pressure versus time curves for pulsed flow can be matched fairly closely by a solution of Euler's equation employing the friction factors measured under steady flow conditions.  相似文献   
2.
3.
The database structure and data manipulation capabilities of a generalized PICture Database Management System (PICDMS) are presented. They are based on a dynamic, stacked-image, logical database structure that uses gridded, rather than topological, data representation. A prototype PICDMS has been designed and implemented. A commercial version is being used as a generator of image processing programs. The system has novel capabilities for nonprogrammer users: it is able to 1) build multiple-variable databases from photographs and other two-dimensional data sources such as maps, drawings, etc., and 2) manipulate such data using simple logical commands. Physical organization and accessing strategies are outlined. A summary of the PICDMS data manipulation capabilities is presented and a subset of operations is illustrated with brief examples. A comprehensive example displays PICDMS capabilities and the programming advantages it possesses over other approaches.  相似文献   
4.
The increasing prevalence of inflammatory diseases and the adverse effects associated with the long-term use of current anti-inflammatory therapies prompt the identification of alternative approaches to reestablish immune balance. Apigenin, an abundant dietary flavonoid, is emerging as a potential regulator of inflammation. Here, we show that apigenin has immune-regulatory activity in vivo. Apigenin conferred survival to mice treated with a lethal dose of Lipopolysaccharide (LPS) restoring normal cardiac function and heart mitochondrial Complex I activity. Despite the adverse effects associated with high levels of splenocyte apoptosis in septic models, apigenin had no effect on reducing cell death. However, we found that apigenin decreased LPS-induced apoptosis in lungs, infiltration of inflammatory cells and chemotactic factors’ accumulation, re-establishing normal lung architecture. Using NF-κB luciferase transgenic mice, we found that apigenin effectively modulated NF-κB activity in the lungs, suggesting the ability of dietary compounds to exert immune-regulatory activity in an organ-specific manner. Collectively, these findings provide novel insights into the underlying immune-regulatory mechanisms of dietary nutraceuticals in vivo.  相似文献   
5.
Most of today’s business processes are based solely on digital data. Input, output, and intermediate results are pure digital objects. Keeping such data accessible and meaningful but even more importantly keeping the business processes functional is challenging. With regards to complex electronic business processes traditional archiving does not provide satisfactory results. Due to the fast technical life-cycle the time gap between archiving and re-enactment or reuse of a process poses risks and increases the uncertainty on achievable results. We propose a novel strategy bridging this specific time gap. For this we present a scalable and cost-effective infrastructure with associated workflows focusing on a process’ execution context. Most importantly the process’ developers are able to assess the preserved results in a timely manner, and thus, reduce the uncertainty on future re-enactment results.  相似文献   
6.
In order to activate the polymers for electroless copper deposition, an alternative way of sample preparation is demonstrated. The samples are prepared by incorporation of a small amount (<1 wt %) of palladium, nickel, or copper acetate into the molten Liquid Crystal Polymer (LCP) in a blender. Since the blending temperature is kept higher than the decomposition temperature of acetates, the acetates are thermally decomposed during blending, leading to the metallic Pd, Ni, or Cu which are used as activators for electroless deposition. After preparing the samples, electroless copper deposition is successfully realized. The influence of different acetates (Pd, Ni, or Cu acetates) on the deposition is investigated. The copper amount is higher and the deposition kinetics is faster on LCP samples with 0.15 wt % Pd and 0.4 wt % Ni than that with 0.4 wt % Cu. The deposited copper layers are uniform and oxide‐free. Moreover, the possibility to substitute expensive Pd activator by cheaper Ni or Cu is shown. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44397.  相似文献   
7.
8.
A knowledge-based approach to retrieve medical images by feature and content with spatial and temporal constructs is developed. Selected objects of interest in an image are segmented and contours are generated. Features and content are extracted and stored in a database. Knowledge about image features can be expressed as a type abstraction hierarchy (TAH), the high-level nodes of which represent the most general concepts. Traversing TAH nodes allows approximate matching by feature and content if an exact match is not available. TAHs can be generated automatically by clustering algorithms based on feature values in the databases and hence are scalable to large collections of image features. Since TAHs are generated based on user classes and applications, they are context- and user-sensitive. A knowledge-based semantic image model is proposed to represent the various aspects of an image object's characteristics. The model provides a mechanism for accessing and processing spatial, evolutionary and temporal queries. A knowledge-based spatial temporal query language (KSTL) has been developed that extends ODMG's OQL and supports approximate matching of features and content, conceptual terms and temporal logic predicates. Further, a visual query language has been developed that accepts point-click-and-drag visual iconic input on the screen that is then translated into KSTL. User models are introduced to provide default parameter values for specifying query conditions. We have implemented the KMeD (Knowledge-based Medical Database) system using these concepts  相似文献   
9.
Accumulating evidence suggests that anxiety sensitivity (fear of arousal-related sensations) plays an important role in many clinical conditions, particularly anxiety disorders. Research has increasingly focused on how the basic dimensions of anxiety sensitivity are related to various forms of psychopathology. Such work has been hampered because the original measure--the Anxiety Sensitivity Index (ASI)--was not designed to be multidimensional. Subsequently developed multidimensional measures have unstable factor structures or measure only a subset of the most widely replicated factors. Therefore, the authors developed, via factor analysis of responses from U.S. and Canadian nonclinical participants (n = 2,361), an 18-item measure, the ASI-3, which assesses the 3 factors best replicated in previous research: Physical, Cognitive, and Social Concerns. Factorial validity of the ASI-3 was supported by confirmatory factor analyses of 6 replication samples, including nonclinical samples from the United States and Canada, France, Mexico, the Netherlands, and Spain (n = 4,494) and a clinical sample from the United States and Canada (n = 390). The ASI-3 displayed generally good performance on other indices of reliability and validity, along with evidence of improved psychometric properties over the original ASI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
Optical community has expressed a wide consensus over the idea that 1 mm poly-methil-meta-acrilate step-index fibres (PMMA SI-POF) can be a good candidate in future domotic networks and in edge networks, that is in the last part of access networks, due to their better mechanical behaviour and lower installation and handling costs with respect to conventional 50/125 or 62.5/125 multi-mode glass fibres. Current applications are anyway limited by relatively low transmission performances: up to now, the best performing commercial Ethernet transceivers using PMMA SI-POF are able to reach at the most 200 m at 10 Mb/s or 70 m at 100 Mb/s, thereby keeping these fibres in the niche of very-short reach applications, such as in the automotive market. A Prototype of a media converter for fully compliant 10 Mb/s Ethernet transmissions over PMMA SI-POF experimentally demonstrated the feasibility of >400 m long link, this length may open new applications to PMMA SI-POF. The 425-m record distance presented here has been achieved by both introducing a proprietary protocol implemented over a field programmable gate array platform and by a careful selection of (commercial) optoelectronic components. The prototype is to be considered as a proof-of-concept that PMMA SI-POF can be introduced in new areas such as the last part of access/edge networks or datacom applications in industrial automation or aircrafts/ships cabling. The 400-m distance is, for instance, the specification of an Italian fibre to the home operator for the last part of its access network architecture  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