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排序方式: 共有139条查询结果,搜索用时 15 毫秒
1.
SA Syed KS Zahir JR Zink O Saglaam RJ Restifo JG Thomson 《Canadian Metallurgical Quarterly》1997,38(4):396-403
Reinstatement and spontaneous recovery of previously extinguished nicotine-taking behavior were examined in rats. Male subjects were trained to self-administer nicotine (30 microg/kg per infusion, IV; one 60-min session per day for 3 weeks). Extinction sessions were then given for 5-10 days during which saline was substituted for nicotine. Subsequently, in the first set of tests for nicotine seeking, the reinstatement of lever presses that previously delivered nicotine was examined after priming injections of saline and nicotine (75, 150 and 300 microg/kg, SC; and 30 and 60 microg/kg, IV). In the second set of tests for nicotine-seeking, rats were tested after an additional 21-day drug-free period during which they were not exposed to the self-administration chambers (a test for the spontaneous recovery of drug seeking), and after priming injections of nicotine (150 and 300 microg/kg, SC). Reinstatement of extinguished food-reinforced behavior after exposure to nicotine was also determined. Priming injections of nicotine reinstated nicotine seeking regardless of the route of administration. In addition, previously extinguished nicotine seeking recovered spontaneously after a 21-day period during which rats were not exposed to the drug-taking environment. Nicotine also reinstated extinguished food-reinforced behavior in rats with a history of nicotine self-administration, but not in drug-naive rats. The present results extend previous work with opioid and stimulant drugs on reinstatement of drug seeking by the self-administered drug. It also appears that, as with other positive reinforcers, the mere passage of time is a sufficient condition for the spontaneous recovery of extinguished nicotine seeking. 相似文献
2.
The content and positional distribution of CLA in TAG fractions of lamb tissues was examined with either preformed CLA or
the linoleic acid precursor of CLA in the diet as experimental treatments. The CLA content of phospholipid (PL) from these
tissues was also examined. Thirteen lambs were randomized to the following dietary treatments: (i) control diet (no supplement);
(ii) CLA supplementation (0.33 g d−1 for 21 d prior to weaning) to milk-replacer of pre-ruminating lambs, or (iii) feeding linoleic acid-rich oil (6% safflower
oil on a dry matter basis) to weaned ruminating lambs. At slaughter, tissue samples were procured from diaphragm, rib muscle,
and subcutaneous (SC) adipose tissue. Safflower oil supplementation in the diet resulted in an increase in CLA content of
the TAG from diaphragm, rib muscle, and SC adipose tissue by about threefold (P<0.05) on a mol% basis. CLA was localized to the sn-1/3 positions of TAG. Animals that received pre-formed CLA, however, had increased proportions of CLA at the sn-2 position of TAG from SC adipose tissue, suggesting that there were tissue-specific dietary effects and possible age-related
effects on the mode of FA incorporation into TAG. Safflower oil supplementation in the diet had no effect on the CLA content
of PL from diaphragm, rib muscle, and SC adipose tissue, suggesting that CLA was preferentially incorporated into the TAG
of these tissues. 相似文献
3.
Mohammad Mizanur Rahman Md. Hasan Zahir Md. Eyasin Arafat Mohammad Abu Jafar Mazumder Rami Suleiman A. Madhan Kumar 《应用聚合物科学杂志》2021,138(9):49904
A waste material called oil fly ash (OFA) was acid-functionalized, yielding f-OFA-COOH, which was then reacted with cerium oxide (CeO2) to make CeO2-functionalized OFA, or f-OFA-CeO2. Pristine OFA and f-OFA-CeO2 were used to make waterborne polyurethane (WBPU) dispersions, referred to as WBPU/OFA and WBPU/f-OFA-CeO2, respectively, with defined OFA and f-OFA-CeO2 content. All the dispersions were applied to mild steel as organic coatings to evaluate their protective properties, such as their hydrophobicity, adhesive strength and UV-shielding resistance. These protective properties varied based on the OFA and f-OFA-CeO2 content. The highest water contact angle, minimum water swelling and maximum adhesive strength were found using WBPU/f-OFA-CeO2-20 coating (using 2.00 wt% f-OFA-CeO2), which also showed the maximum ultraviolet (UV) absorption via UV–vis spectroscopy analysis. This UV shielding result also matched field test results, as that coating was found to exhibit the lowest UV degradation near a marine atmosphere, as shown by X-ray photoelectron spectroscopy (XPS) analysis. The least affected hydrophobicity was also recorded for the sample with the WBPU/f-OFA-CeO2-20 coating. 相似文献
4.
Vishanth Weerakkody Zahir Irani Habin Lee Nitham Hindi Ibrahim Osman 《Information Systems Management》2016,33(4):331-343
Citizens’ satisfaction is acknowledged as one of the most significant influences for e-government adoption and diffusion. This study examines the impact of information quality, system quality, trust, and cost on user satisfaction of e-government services. Using a survey, this study collected 1518 valid responses from e-government service adopters across the United Kingdom. Our empirical outcomes show the five factors identified in this study have a significant impact on U.K. citizens’ satisfaction with e-government services. 相似文献
5.
Adil Fahad Zahir Tari Ibrahim Khalil Ibrahim Habib Hussein Alnuweiri 《Computer Networks》2013,57(9):2040-2057
There is significant interest in the network management and industrial security community about the need to identify the “best” and most relevant features for network traffic in order to properly characterize user behaviour and predict future traffic. The ability to eliminate redundant features is an important Machine Learning (ML) task because it helps to identify the best features in order to improve the classification accuracy as well as to reduce the computational complexity related to the construction of the classifier. In practice, feature selection (FS) techniques can be used as a preprocessing step to eliminate irrelevant features and as a knowledge discovery tool to reveal the “best” features in many soft computing applications. In this paper, we investigate the advantages and disadvantages of such FS techniques with new proposed metrics (namely goodness, stability and similarity). We continue our efforts toward developing an integrated FS technique that is built on the key strengths of existing FS techniques. A novel way is proposed to identify efficiently and accurately the “best” features by first combining the results of some well-known FS techniques to find consistent features, and then use the proposed concept of support to select a smallest set of features and cover data optimality. The empirical study over ten high-dimensional network traffic data sets demonstrates significant gain in accuracy and improved run-time performance of a classifier compared to individual results produced by some well-known FS techniques. 相似文献
6.
Microprocessors continue on the relentless path to provide more performance. Every new innovation in computing-distributed computing on the Internet, data mining, Java programming, and multimedia data streams-requires more cycles and computing power. Even traditional applications such as databases and numerically intensive codes present increasing problem sizes that drive demand for higher performance. Design innovations, compiler technology, manufacturing process improvements, and integrated circuit advances have been driving exponential performance increases in microprocessors. To continue this growth in the future, Hewlett Packard and Intel architects examined barriers in contemporary designs and found that instruction-level parallelism (ILP) can be exploited for further performance increases. This article examines the motivation, operation, and benefits of the major features of IA-64. Intel's IA-64 manual provides a complete specification of the IA-64 architecture 相似文献
7.
Sofiane Guessasma Zahir Salhi Ghislain Montavon Patrick Gougeon Christian Coddet 《Materials Science and Engineering: B》2004,110(3):285-295
Thermal spray process is a technique of coating manufacturing implementing a wide variety of materials and processes. This technique is characterized by up to 150 processing parameters influencing the coating properties. The control of the coating quality is needed through the consideration of a robust methodology that takes into account the parameter interdependencies, the process variability and offers the ability to quantify the processing parameter-process response relationships. The aim of this work is to introduce a new approach based on artificial intelligence responding to these requirements. A detailed procedure is presented considering an artificial neural network (ANN) structure which encodes implicitly the physical phenomena governing the process. The implementation of such a structure was coupled to experimental results of an optic sensor controlling the powder particle fusion state before the coating formation. The optimization steps were discussed and the predicted results were compared to the experimental ones allowing the identification of the control factors. 相似文献
8.
In this work we considered the stability of a single-bit high-order sigma-delta modulator under dc input. A new approach for stability analysis is proposed. A nonlinear circle map is suggested to model the dynamics of the modulator. An analogy between the dynamics of the sigma-delta modulator and the sinusoidal digital phase-locked loop (DPLL) is studied and an approximate fixed point solution is presented with stability criteria. Suggestions for designing stabilized high-order systems are presented. 相似文献
9.
Three experiments provide evidence that 2 mechanisms, 1 automatic and 1 controlled, produce variations in the efficiency with which local and global forms are processed. Targets are identified faster if they appear at the same level (global or local) as the target on the previous trial. M. R. Lamb, B. London, H. M. Pond, and K. A. Whitt (see record 1997-39043-003) provided evidence that the beneficial effect of level repetition is due to an automatic process that is outside voluntary control. In the present experiments, pretrial cues informed participants as to the level of the upcoming target. Valid cues benefited performance, whereas invalid cues harmed performance relative to noninformative neutral cues. This was so even when the relation between the cue and the level it signaled was arbitrary, indicating that the cues initiated voluntary shifts of attention. The benefit associated with level repetition, however, was unaffected by the cues. These data suggest that the benefit of level repetition results from a process that is not subject to voluntary control. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Zahir Nikraftar Esmaeel Parizi Seiyed Mossa Hosseini Behzad Ataie-Ashtiani 《Journal of Great Lakes research》2021,47(4):955-969
Lake Urmia is the second-largest hypersaline lake in the world. There has been a drastic water level drop of 7.2 m from 1995 to 2016. Beginning in October 2013, the Lake Urmia Restoration Plan (LURP) launched a 10-year program. An increase in water level and a relative improvement in Lake Urmia condition has been observed since 2017. It is an undecided and controversial issue whether the recent positive trend of Lake Urmia has been due to the LURP activities or it is a natural contribution of climate factors variations. To shed some light on this issue, we examine three other lakes, adjacent to the Lake Urmia basin, with similar rainfall variability to investigate their status during the same period. Van (Turkey), Mosul, and Tharthar (both in Iraq), are evaluated as well as Lake Urmia. Three decades of remotely sensed data including precipitation (), water level (), and lake extent () were considered for the mentioned lakes. A significant correlation was observed between standardized , and over the long-term period, especially for the recent three years (2 = 0.63–0.87). We show that the cumulative precipitation in the antecedent months played a major role in the improvement of these lakes' situation but with different time lags (up to 6 months for Van and Mosul lakes and up to 36 months for Lake Urmia and Tharthar lake). These findings could inform the planners of LURP to adopt strategies for achieving a sustainable state of Lake Urmia based on a more realistic outlook. 相似文献