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排序方式: 共有21条查询结果,搜索用时 31 毫秒
1.
This paper describes the implementation and evaluation of a nonsanction seat belt law enforcement program in two experimental communities of contrasting size in a state with a mandatory belt law. The main ingredients of the program were seat belt "salutes," public information and education, and limited use of inexpensive economic incentives. Driver shoulder belt use data collected before, during, and after the experimental programs, compared to similar data collected in a comparison community, showed the approach to be effective. While standard seat belt enforcement activities without incentives have been shown to be effective, many police departments, especially in smaller communities, are reluctant to make wholesale increases in seat belt citations. Although requiring some additional level of manpower and resources, a nonsanction approach to seat belt law enforcement can provide an alternate way of increasing belt use in these communities.  相似文献   
2.
A single-element tuning fork piezoelectric linear actuator   总被引:1,自引:0,他引:1  
This paper describes the design of a piezoelectric tuning-fork, dual-mode motor. The motor uses a single multilayer piezoelectric element in combination with tuning fork and shearing motion to form an actuator using a single drive signal. Finite-element analysis was used in the design of the motor, and the process is described along with the selection of the device's materials and its performance. Swaging was used to mount the multilayer piezoelectric element within the stator. Prototypes of the 25-mm long bidirectional actuator achieved a maximum linear no-load speed of 16.5 cm/s, a maximum linear force of 1.86 N, and maximum efficiency of 18.9%.  相似文献   
3.
The spatial and temporal aspects of immune cell signaling are key parameters in defining the magnitude of an immune response. Toll‐like receptors (TLRs) on innate immune cells are important in the early detection of pathogens and initiation of an immune response. Controlling the spatial and temporal signaling of TLRs would enable further study of immune synergies and assist in the development of new vaccines. Here, we show a light‐based method for the spatial control of TLR4 signaling. A TLR4 agonist, pyrimido[5,4‐b]indole, was protected with a cage at a position critical for receptor binding. This afforded a photocontrollable agonist that was inactive while caged, yet effected NF‐κB activity in cells following UV photocontrolled deprotection. We demonstrated spatial control of NF‐κB activation within a population of cells by treating all cells with the caged TLR4 agonist and constraining light exposure and consequent activation to a region of interest.  相似文献   
4.
Bicycle accident and injury data collected by two different samples of North Carolina hospital emergency rooms during the summers of 1985 and 1986 are examined and compared with state police-reported bicycle accident data for the same time periods. Of the 649 emergency room treated bicyclists, 62% were children aged 5-14 and 70% were male. Nineteen percent of the riders suffered moderate or worse injuries (AIS greater than or equal to 2), and 6% were hospitalized. In contrast, less than half of the police-reported accidents involved riders under 15 years of age, 85% of the riders were male, and two-thirds suffered moderate or worse injury. Whereas virtually all of the police-reported accidents involved a motor vehicle, less than a fifth of the emergency room cases did. Only 10% of the emergency room cases were duplicated on the state accident files. It is estimated that 800 children ages 0-19 are hospitalized annually in North Carolina for bicycle-related injuries, and an additional 13,300 children receive emergency room treatment.  相似文献   
5.
OBJECTIVE: To determine whether older drivers with poorer cognitive and/or visual function drive fewer miles or avoid driving in situations that pose higher crash risks, such as at nighttime, in rush hour traffic, or when weather conditions are bad. DESIGN: A cross-sectional data analysis conducted as part of a larger prospective study. SUBJECTS: A total of 3238 drivers aged 65 and older applying for renewal of their driver's license at one of eight participating North Carolina driver's license offices. MEASUREMENTS: Subjects were administered a battery of brief tests of cognitive and visual function, which included the Trail Making Test Parts A and B, the Short Blessed Orientation-Memory-Concentration test, and measures of high and low contrast visual acuity, contrast sensitivity, and peripheral vision. Participants were also asked to complete a brief driving survey containing questions about the number of miles they drove and whether they avoided driving under certain conditions, such as after dark or on busy, multi-lane roadways. Driver age and gender were covariates in the analyses. RESULTS: Results of multivariate logistic regression models show a clear pattern of reduced driving exposure--lower annual miles and greater avoidance of high-risk driving situations--associated with lower levels of cognitive and visual function. In general, the prevalence odds of reduced driving exposure were higher for the cognitive function variables than for the visual function variables, and higher for males than for females. Men who scored in the lowest quartile of performance on one of the cognitive tests were six to seven times more likely to report driving fewer than 3000 miles a year than were men scoring in the highest quartile, and women with low scores were one-and-one-half to two times more likely to report driving less than 3000 miles than women with higher scores. CONCLUSIONS: While the findings of this study are reassuring, they do not guarantee that all drivers with cognitive and visual impairments are limiting their driving exposure appropriately, and geriatricians and other health professionals should be encouraged to evaluate their patients' cognitive and visual fitness for driving and provide counsel where indicated.  相似文献   
6.
A sensor to measure the stator torsional vibration due to torque ripple produced by a surface mount permanent magnet machine is first described. The sensor is relatively inexpensive and is straight forward to incorporate into a drive system. Experiments are performed to validate that the voltage produced by the sensor is linearly related to torque ripple amplitude. Closed-loop controllers are then described that adjust the stator current harmonics applied to the machine to achieve a commanded average torque while mitigating measured torsional vibration. Simulation and experimental results are used to demonstrate the effectiveness of the control techniques.  相似文献   
7.
Unobtrusive video camera units were installed in the vehicles of 70 volunteer drivers over 1-week time periods to study drivers’ exposure to distractions. The video data were coded based on a detailed taxonomy of driver distractions along with important contextual variables and driving performance measures. Results show distractions to be a common component of everyday driving. In terms of overall event durations, the most common distractions were eating and drinking (including preparations to eat or drink), distractions inside the vehicle (reaching or looking for an object, manipulating vehicle controls, etc.), and distractions outside the vehicle (often unidentified). Distractions were frequently associated with decreased driving performance, as measured by higher levels of no hands on the steering wheel, eyes directed inside rather than outside the vehicle, and lane wanderings or encroachments. Naturalistic driving studies can provide a useful supplement to more controlled laboratory and field studies to further our understanding of the effects of all types of distractions on driving safety.  相似文献   
8.
During the summer of 1987, 10,000 color-coded mailback questionnaires that identified belted and unbelted North Carolina drivers were handed out at the 72 sites that constitute the probability sample for determining the statewide belt use rate in North Carolina. By obtaining identifying information to determine the winner of a $500 prize from among the 5,074 respondents, police-reported traffic accident and conviction records from the North Carolina driver history file were linked to the belted and unbelted respondents. Analyses found that drivers who had been observed not wearing seat belts had 35% more accidents and 69% more convictions than did belted drivers in the previous four-year period. Similar findings were obtained from self-reported belt use.  相似文献   
9.
The electrochemical reduction of 3-nitro-4-hydroxybenzoic acid (1) in basic medium at a copper cathode is a facile process and has been scaled to produce over 35 kg of the corresponding aniline (2) isolated as the HCl salt. The trifunctional compound is an important intermediate for the synthesis of polybenzoxazoles and can be self-polymerized to produce an a-b type polymer.  相似文献   
10.
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