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排序方式: 共有1459条查询结果,搜索用时 15 毫秒
81.
Enhancing the effectiveness of tobacco package warning labels: a social psychological perspective 总被引:5,自引:0,他引:5
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OBJECTIVE: To outline social psychological principles that could influence the psychosocial and behavioural effects of tobacco warning labels, and to inform the development of more effective tobacco warning labels. DATA SOURCES: PsycInfo and Medline literature searches and expert guided selection of principles and theories in social psychology and of tobacco warning labels, including articles, books, and reports. CONCLUSIONS: Tobacco warning labels represent a potentially effective method of influencing attitudes and behaviours. This review describes social psychological principles that could be used to guide the creation of more effective warning labels. The potential value of incorporating warning labels into a broader public health education campaign is discussed, and directions for future research are suggested. 相似文献
82.
Web-based e-commerce software is typically real-time, responsive, and distributed software that must meet high quality requirements.
Moreover, because of its Internet-based operating environment, e-commerce software must deal with concurrency, synchronization,
and non-deterministic issues (such as delays) primarily caused by the heavy usage load and underlying network conditions.
In this paper, we introduce a generic, cost-effective approach to optimize requirements capture (and subsequent development
and testing) with respect to functional coverage and customer perception of quality. This high-yield approach is presented
and illustrated by application to an e-commerce online shopping system and used to explain the principles of use-case requirements
captured in the unified modeling language.
Published online: 25 July 2001 相似文献
83.
Li W Gu C Zhang H Awang DV Fitzloff JF Fong HH van Breemen RB 《Analytical chemistry》2000,72(21):5417-5422
A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed to distinguish Asian ginseng (Panax ginseng C. A. Meyer) and North American ginseng (Panax quinquefolius L.). The method is based on the baseline chromatographic separation of ginsenoside Rf and 24(R)-pseudoginsenoside F11, two potential chemical markers present in ginseng root methanolic extracts, and their unambiguous on-line identification using tandem mass spectrometry. Consistent with the literature, 24(R)-pseudoginsenoside F11 was detected in abundance in North American ginseng roots in excess of 0.1% (w/w) of the dried root. In contrast to some reports, 24(R)-pseudoginsenoside F11 was also identified in Asian ginseng roots at trace levels using LC-MS-MS but at less than 0.0001% (w/w). Besides showing identical tandem mass spectra to authentic 24(R)-pseudoginsenoside F11, the corresponding compound in Asian ginseng root coeluted with standard under different HPLC conditions, thus confirming this compound as 24(R)-pseudoginsenoside F11. Another ginsenoside often used to distinguish Asian and North American ginseng, ginsenoside Rf, was found in abundance in Asian ginseng roots at more than 0.021% (w/w). In Asian ginseng roots, the ratio of ginsenoside Rf to 24(R)-pseudoginsenoside F11 exceeded 700:1. The limit of detection of ginsenoside Rf or 24(R)-pseudoginsenoside F11 was 120 pg injected on-column, and the limit of quantification was 240 pg on-column. In summary, LC-MS-MS analysis of ginseng products for the presence and ratio of ginsenoside Rf and 24(R)-pseudoginsenoside F11 may be used for the unambiguous identification of Asian and North American ginsengs. 相似文献
84.
分析了最大匹配法中匹配字段选取长度及匹配结束问题,提出了首字词最大匹配法,在此基础上计算时间复杂性。 相似文献
85.
华东500kV电网谐波问题初探 总被引:1,自引:0,他引:1
针对华东500kV电网电压谐波率较大的现状,分析了谐波源主要来自500kV变压器和高压电抗器。这些谐波源的谐波电流数值并不大,但由于500kV电网自身阻抗可能使谐波分量起了放大作用,本文对此作了分析探讨。本文还就谐波电压的测量方法、减小测量附加误差、谐波电压限值和控制对策作了叙述。 相似文献
86.
Kirby W. Fong 《Software》1985,15(1):87-103
The National Magnetic Fusion Energy Computer Center (NMFECC) at the Lawrence Livermore National Laboratory (LLNL) has implemented a simple, yet powerful interactive operating system, the Cray Time-Sharing System (CTSS), on a Cray-1 supercomputer. CTSS augments the multi-programming batch facilities normally found in supercomputer systems with many of the interactive services typical of interactive minicomputer systems. This paper gives some of the historical background leading to CTSS and gives an overview of the system that emphasizes the strong points or unusual features such as multiple channels, decentralized control of resources, priorities and program scheduling, system recovery, and on-line documentation. 相似文献
87.
88.
An increasing number of hepatic resections are being performed as potentially curative surgery for malignant liver neoplasms. Hepatectomy and subsequent liver regeneration produce a local environment that enhances growth of microscopic residual tumor. To determine if pretreatment with murine interferon gamma (IFN-gamma) can protect against such enhanced tumor growth, Buffalo rats were randomized to receive a 3-day treatment of IFN-gamma (50,000 U/qD intraperitoneally) or saline. Groups then underwent intrasplenic injection of 10(6) Morris hepatoma cells, followed 1 hour later by sham (control) or partial hepatectomy (PH) of 70%. PH significantly enhanced tumor growth within the liver (control, 8 +/- 3 nodules per liver; PH, 73 +/- 12 nodules per liver; P < .001). This enhancement was attenuated by prior administration of IFN-gamma IFN-gamma/PH, 16 +/- 3; P < .001 vs. PH). Growth factor release and liver regeneration were not affected significantly by pretreatment with IFN-gamma. The effect of IFN-gamma on tumor growth is associated with a significant enhancement of Kupffer cell (KC)-mediated tumoricidal activity (percentage of specific lysis, 55 +/- 10% control, 78 +/- 11% IFN-gamma, P < .01) but not lymphocyte-mediated tumoricidal activity. Because microscopic residual disease may be present after hepatectomies for cancer, IFN-gamma may be useful agent in retarding growth of residual tumors. 相似文献
89.
粉煤旋风燃烧器颗粒运动轨迹数学模拟实验研究 总被引:3,自引:0,他引:3
在粉煤燃烧规律研究中,有些物性及工况参数的影响,目前还很难完全利用物理模型进行直接准确的测定。本文是在对四种不同结构的粉煤旋风燃烧器模型的多温三维流场测试的基础上,对流场测试结果进行优化处理,得出四种情况下的流场速度分布规律的拟合函数式;而后分析了颗粒在气相场内的受力情况,建立了粉煤颗粒在三维流场内运动轨迹的数学模型;把测试结果与数学模拟结合起来,籍助计算机,计算并考察了不同粒度和密度的粉煤颗粒在某些初始条件下的运动轨迹;研究了四种结构燃烧器在不同物理条件和初始条件下的粒子运动变化规律及其着壁条件。 相似文献
90.
RH Bartlett AB Gazzaniga SW Fong MR Jefferies HV Roohk N Haiduc 《Canadian Metallurgical Quarterly》1977,73(3):375-386
We have used extracorporeal membrane oxygenation (ECMO) for 28 patients (14 children and 14 adults) over a 5 year period. Nine patients improved on ECMO and 5 were long-term survivors. ECMO was used for pulmonary insufficiency in 24 patients. Initially, only moribund patients were treated, but recently the combination of open lung biopsy and pulmonary insufficiency index (PII) has been used to select patients. The best results have been obtained in newborn cases and the adult capillary leak syndromes; the major problem has been progression to fibrosis despite ECMO support. ECMO was used for cardiac failure in 4 patients. Children with postoperative cardiac failure did the best; profound shock was not reversed with venoarterial bypass. ECMO support is lifesaving in selected cases of pulmonary insufficiency. Initial trials in cardiac failure and the infant age group in this series suggest that ECMO will have an even greater role in those applications. 相似文献