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   22篇
  免费   0篇
工业技术   22篇
  2017年   1篇
  2016年   1篇
  2010年   1篇
  2006年   1篇
  2005年   1篇
  2002年   1篇
  2000年   2篇
  1999年   1篇
  1997年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1987年   1篇
  1986年   2篇
  1977年   2篇
  1976年   1篇
排序方式: 共有22条查询结果,搜索用时 0 毫秒
1.
We review research and evaluate the economics of short-rotation intensive culture (SRIC) for the production of wood energy feedstocks in six regions of the U.S. The economics of SRIC are evaluated for present conditions under two sets of assumptions about anticipated advances in technology. The results show that delivered SRIC feedstock costs using available technology are likely to range between $3.00 and $4.10/GJ. Based on estimates of technological advances in tree breeding and selection, cultural management, and harvesting, delivered costs could be lowered to under $2.00/GJ. Advances in genetics, cultural management, and harvesting needed to reduce SRIC costs are technically attainable by the year 2000.  相似文献   
2.
3.
Helmets significantly decrease morbidity and mortality from motorcycle crashes, but many areas of the world lack universal helmet laws. To educate motorcyclists in areas without helmet laws, more knowledge of motorcyclists’ helmet beliefs is needed.A web-based survey was therefore designed to assess motorcyclists’ attitudes, norms and behaviors towards helmets in a U.S. state with a limited helmet law. Of 445 survey respondents, 68.4% of respondents reported always wearing a helmet. The not-always-helmeted riders were more likely than the always-helmeted to be male; to bave less education; and to have a history of previous motorcycle crashes and injuries. Although both groups had taken rider training classes, fewer of the not-always-helmeted had learned how to ride in a class. The strongest correlates of being not-always-helmeted (vs. always-helmeted) were attitudes that helmets were not protective and impaired sight/hearing; and the normative belief that they would only wear helmets if forced by law. Because attitudes are often more easily changed than normative beliefs, education may increase helmet use. However, less than half of riders in this state with a mandatory education program learned how to ride from a rider education course, and 44% of non-helmeted said they would only wear a helmet if forced by law. Legislation may therefore be a more efficient and effective strategy than education to increase helmet use.  相似文献   
4.
Accident studies have identified nighttime conditions on rural roads as particular problems for alcohol-impaired drivers. Uneventful driving is hypothesized to result in progressive degradation of tracking performance and a reduced ability to handle the demands of hazardous locations, such as curves. To address these problems, four spot treatments (i.e. herringbone road marking, flashing beacon, chevron, and post delineator) were evaluated in a driving simulator. Twelve subjects drove a simulator under two conditions of task demand (with and without obstacles) and three levels of blood alcohol concentration (BAC): .00%, .07%, and .12%. The purpose of the study was to determine whether providing enhanced visual information about hazardous areas would improve the performance of subjects when sober or alcohol-dosed. Driver performance measures included speed, lateral position, and lateral acceleration on the approach and negotiation of horizontal curves of varying length and curvature. The results indicate that spot treatment effects were primarily curve-specific rather than uniform across curves. The effectiveness of spot treatments as alcohol countermeasures is discussed.  相似文献   
5.
J. J. Freyd et al (see record 1989-14372-001) provided considerable evidence for the proposition that people can represent underlying forces within static scenes. However, they explicitly assumed that their observed memory shifts were the result of perceptually modular information processing. For several reasons, I suggest herein that this assumption of cognitive impenetrability is a dubious one. The assumption is challenged by recent empirical findings, some theoretical considerations, and calculations that show that the observed effects are minute when compared with those expected by means of physical forces. Three explanations for the evidence are proposed, including the alternative hypothesis that although people do represent static physical forces, these representations can be almost completely overridden by the conscious intention to remember an object's precise location. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Models of driving behavior: A review of their evolution   总被引:3,自引:0,他引:3  
This paper reviews models that emphasize the cognitive components of driving behavior. Studies of individual differences have sought predictors of accident histories. Typically low correlations and reliance on post hoc explanations reflect theoretical deficiencies and problems with the use of accident measures. Motivational models emphasize transient, situation-specific factors rather than stable, individual predictors. However, neither testable hypotheses nor suitable methods have been developed to study situational factors and motives that influence driving. More recent models have incorporated a hierarchical control structure, which assumes concurrent activity at strategic, maneuvering, and operational levels of control. At the same time, automaticity has emerged as a central construct in cognitive psychology. All activities are assumed to combine fast, automatic components with slower, more deliberate, controlled processing. It is argued that identifying the situational factors that increase drivers' uncertainty and thus trigger a shift in attention from automatic to controlled processing will help integrate concepts of automaticity and motivational models. Finally, recent theorizing has suggested that errors associated with the inherent variability of human behavior may be more important to roadway crash causation than systematic errors, which are attributable to the known limits of the human information-processing system. Drivers' abilities to recover from errors may also be important to crash causation. It is concluded that the hierarchical control structure and theories of automaticity and errors provide the potential tools for defining alternative criterion measures, such as safety margins, and developing testable theories of driving behavior and crash causation. Two examples of models that integrate information-processing mechanisms within a motivational framework are described.  相似文献   
7.
A systematic approach for identifying and quantifying molecular components of complex organic aerosol mixtures is presented. The approach combines methods developed previously for derivatizing carbonyl, hydroxyl, carboxyl, and ester functional groups, which are commonly present in oxidized organic aerosol, with liquid chromatography, UV detection, and chemical ionization-ion trap mass spectrometry. The original derivatization-spectrophotometric methods were modified for compatibility with liquid chromatography and then evaluated by analyzing a variety of standard compounds that contain one or more functional groups. Detection limits for carbonyl, hydroxyl, carboxyl, and ester analysis are approximately 0.003, 0.02, 0.01, and 1 nmole, respectively. Mass spectral analysis of derivatives using isobutane and ammonia as reagent gases for chemical ionization can be used to determine compound molecular weight, and characteristic fragmentation patterns provide structural information for use in compound identification. The methods will be useful for analyzing the chemical composition of secondary organic aerosol (SOA) formed in laboratory studies to obtain information needed to develop quantitative reaction mechanisms that can be incorporated into atmospheric models to better predict the formation, composition, and fate of SOA.

Copyright © 2017 American Association for Aerosol Research  相似文献   

8.
A severe hemolytic crisis was observed in a 34-yr-old female of English-Irish extraction following a viral illness treated with acetaminophen. Heinz bodies and heat instability were present only during a transient hemolytic event. A challenge dose of acetaminophen caused no detectable hematologic abnormality. Structural studies of the hemoglobin during hemolysis and again after complete recovery localized the abnormality to tryptic peptide beta Tp-5, and automated sequencing of I 125-labeled beta chains indicated a replacement of phenylalanine (C7) beta 41 by tyrosine. Substitution of the next residue, phenylalanine (CD1) beta 42 by serine (Hb Hammersmith), has resulted in chronic severe Heinz body hemolytic anemia. The lack of chronic anemia in the present disorder may reflect the different relationships of beta41 and beta 42 and/or the similarities in volume and hydrophobicity of tyrosine and phenylalanine. It is suggested that substitution of tyrosine for phenylalanine in Hb Mequon may disturb the critical environment around the heme group and render it susceptible to oxidative denaturation in the presence of infections and/or drugs.  相似文献   
9.
One of the ways in which chlorine is thought to poison metal catalysts on oxide supports is by altering their dispersion. The effect of chlorine on Cu/ZnO(0001) model catalysts was studied by vapor‐depositing Cu onto Zn‐terminated ZnO(0001), both with and without preadsorbed Cl2, using XPS, ion scattering spectroscopy (ISS), temperature‐programmed desorption (TPD), work function, and band bending measurements. A disordered, but nearly close‐packed overlayer of Cl adatoms forms at saturation with ∼0.30 Cl adatoms per Zn site. Without Cl, vapor‐deposited Cu grows in two‐dimensional islands that cover ∼33% of the ZnO, after which these islands thicken (i.e., as 3D Cu particles) while the clean ZnO between these Cu islands gets covered with Cu only very slowly. Preadsorbed Cl decreases the fraction of the surface that is covered by Cu islands by a factor of three, so Cl(a) either decreases the number of 2D Cu islands or their critical area before thickening. Both are consistent with weaker binding of Cu to the Cl‐covered surface than to the clean ZnO. The TPD features for formate decomposition after HCOOH adsorption onto Cu/ZnO(0001) were suppressed with preadsorbed Cl, but the CO2 : CO selectivity increased. When Cu was deposited onto Cl‐presaturated ZnO, neither the Zn‐ nor Cu‐formate peaks were observed, showing that Cl covers both the Zn sites and the growing Cu islands, as suggested by ISS also. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
10.
This work compares the degradation in driving performance associated with secondary tasks performed with voice-based and visual/manual interfaces, including radio tuning, phone dialing, and more complex tasks involving a sequence of interactions with an in-vehicle computer system. Twenty-one participants drove an instrumented vehicle while performing a combination of car-following, peripheral target detection, and secondary tasks on a closed test track. Drivers compensated for increased task demands associated with secondary tasks by increasing their following distance. Performing secondary tasks also resulted in significant decrements to vehicle control, target detection, and car-following performance. The voice-based interface helped reduce the distracting effects of secondary task performance. Modest improvements were observed for measures of vehicle control and target detection but not for car following. The results indicated that performing in-vehicle tasks required diversion of both peripheral (visual and manual) and attentional (cognitive) resources from driving. The voice-based interface reduced the peripheral impairment but did not appreciably reduce the attentional impairment. Actual or potential applications of this research include improvements to the design of invehicle information systems and the development of evaluation protocols to assess their distraction potential.  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