全文获取类型
收费全文 | 4236篇 |
免费 | 527篇 |
国内免费 | 915篇 |
专业分类
5678篇 |
出版年
2024年 | 14篇 |
2023年 | 107篇 |
2022年 | 133篇 |
2021年 | 148篇 |
2020年 | 279篇 |
2019年 | 260篇 |
2018年 | 259篇 |
2017年 | 269篇 |
2016年 | 306篇 |
2015年 | 184篇 |
2014年 | 258篇 |
2013年 | 766篇 |
2012年 | 197篇 |
2011年 | 258篇 |
2010年 | 147篇 |
2009年 | 222篇 |
2008年 | 195篇 |
2007年 | 208篇 |
2006年 | 190篇 |
2005年 | 186篇 |
2004年 | 161篇 |
2003年 | 140篇 |
2002年 | 108篇 |
2001年 | 89篇 |
2000年 | 79篇 |
1999年 | 56篇 |
1998年 | 51篇 |
1997年 | 49篇 |
1996年 | 37篇 |
1995年 | 54篇 |
1994年 | 33篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 19篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 8篇 |
排序方式: 共有5678条查询结果,搜索用时 15 毫秒
121.
《Médecine & Droit》2020,2020(160):1-5
While the Conseil d’État once again confirmed the legality of the medical decision to stop treatment of Vincent Lambert, the Cour de Cassation held that the French State is not required to suspend the execution of the said decision pending the opinion of the Committee on the Rights of Persons with Disabilities, a United Nations’ body. Nevertheless, the High jurisdiction does not directly pronounce itself on the question of the binding force of the provisions of the Convention on the Rights of Persons with Disabilities and its additional protocol, nor on the scope of these texts. 相似文献
122.
This research study focused on the evaluation of an emulated in-vehicle Active Traffic and Demand Management (ATDM) system on Interstate 66 in Northern Virginia. Traditional ATDM systems rely on infrastructure-mounted variable message signs (VMS) to provide information (speed limits, lane availability, etc.) to the traveling public. By providing information about dynamic roadway conditions on an in-vehicle device, the ATDM may improve driving safety and performance by allowing drivers to remain consistently aware of forthcoming traffic conditions and roadway requirements; even when external signage is inaccessible. This study represents an initial investigation of an emulated in-vehicle ATDM to provide developers with design guidance and ensure that unintended consequences, such as distraction, do not undermine the potential benefits.Twenty younger and 20 older participants, accompanied by a member of the research team, experienced the following ATDM features on an in-vehicle device (IVD) mounted to the dashboard: (1) dynamic speed limits, (2) dynamic lane use/shoulder control, (3) High Occupancy Vehicle (HOV) restrictions, and (4) roadway information from variable message signs. The IVD was equipped with auditory and visual alerts notifying the driver when relevant visual information was updated. Research questions addressed distraction and driver behavior associated with use of the system. Qualitative and quantitative participant data was acquired from the instrumented vehicle, various questionnaires, and researcher observation.Several key findings were uncovered: (1) The IVD, as tested, did not warrant classification as a source of distraction according to the NHTSA guidelines; v2) There was a significant difference in eye-glance durations to the IVD when comparing the VMS alerts to both the speed limit and lane management alerts; and (3) The speed limit alert motivated participants to alter their speed (per survey results and participant speed data). 相似文献
123.
Motor vehicle collisions involving older drivers have increased and become an important social issue. It is known that the decline of cognitive function, including dementia, affects driving performance. A series of studies using the Mini-Mental State Examination (MMSE) and other tests of dementia have attempted to prevent motor vehicle collisions by identifying as early as possible older drivers who may be unable to maintain their driving performance. Further, the performance of older drivers may deteriorate even if they do not have a diagnosis of dementia. Therefore we focused on the relationship between cognitive functioning assessed by the MMSE and diagnosis of leukoaraiosis (LA), or changes in the cerebral white matter, with different aspects of driving behavior resulting from aging. Qualified driving instructors evaluated participants’ driving behaviors on an outdoor driving course at a driving school. Visual search duration and angle at intersections were obtained by wearable wireless sensors. Vehicle speed and minimum vehicle speed were recorded from vehicle speed pulse signals. Duration of signaling and visual searches at unsignalized intersections were recorded using an in-vehicle camera. We assessed instructors’ evaluations and the scores on two instruments to evaluate the effects of MMSE scores and the grade of LA on driving performance were verified. The results suggest that lower MMSE scores and higher LA grade can predict some aspects of poor driving performance in older drivers before they experience dementia or an evident decline in cognitive functioning. Based on these results, we discuss countermeasures that may prevent motor vehicle collisions involving older drivers. 相似文献
124.
Post-delineated express lanes represent a combination of driving complexities that are particularly difficult for older drivers to navigate. The narrow geometry and high speeds that are common to this treatment reflect a critical test for drivers whose depth perception, contrast sensitivity, and visual processing speed are reduced. The present study was designed to empirically examine the effects of age and color of express lane delineators on driver behavior. Three groups of participants (aged 18–39, 40–64, and 65 + years old) were required to complete a series of simulated driving scenarios consisting of combinations of single and dual lane configurations, with speed and lane position measured at the beginning and midpoint of each express lane. All drivers were pre-screened on various visual functioning abilities. Drivers in the 65 and older group show significant age-related declines in depth perception, contrast sensitivity, and phoria which were subsequently correlated with a wide range of driving measures including deceleration rate, brake time, jerk, speed, and lane position. Age related perceptual declines were statistically correlated with slower driving speed and wider lane deviations, including a statistically significant increase in the number of excursions beyond the typical 12-foot lane width. Based on these findings, the behavior of senior drivers was identified as a distinct design condition that should govern the design of high-speed, narrow geometric conditions. This age group requires wider lane widths, particularly at the beginning of single-lane post delimited sections, wider buffer areas around the post markers, and dual lane configurations wherever possible. 相似文献
125.
126.
127.
老年人的视听觉整合能力强于还是弱于年轻人, 目前尚存在很大争议。对老年人视听觉整合脑机制的研究, 将为老年人脑保健提供一种科学的跨通道整合方案。基于已有研究成果从两方面进行论述:1)影响老年人视听觉整合的因素, 包括刺激的物理属性、刺激呈现的时空关系以及刺激得到的注意资源。2)老年人视听觉整合效应。研究表明, 一方面, 老年人表现出更高的功能连接性、网络效率和较强的视听觉整合效应, 如:老年人在后顶叶、内侧前额叶和左前额叶等脑区有较强的激活, 额中央区的P2振幅表现出超加性; 老年人比年轻人的视听觉整合发生较早并有较长的延伸。另一方面, 老年人有较长的反应时和较弱的整合促进, 以及对视听觉刺激进行反应时颞上回脑区的振幅弱于年轻人。简单刺激诱发的老年人视听觉整合为进一步揭示整合机制提供了可靠的基础, 但是对于复杂情景下的视听觉信息整合加工机制仍待探究。 相似文献
128.
消极身体意象是青少年健康成长所面临的重要问题之一。了解消极身体意象对青少年的危害以及其形成的影响因素, 对于青少年群体身心健康发展具有重要意义。消极身体意象对青少年的负面影响主要包括自我概念、情绪体验、体重控制策略、饮食失调和社会生活五个方面; 并且青少年消极身体意象形成的影响因素主要有生物因素(BMI)、社会文化因素(父母、同伴和大众媒体)和心理因素(人格因素、认知方式)。未来可从以下几个方面进一步深入研究:(1) 基于生物-心理-社会模型的视角完善青少年身体意象发展的理论模型; (2) 考察社交媒体等新兴因素的作用; (3) 阐明青少年在加工身体相关信息时的认知特点; (4) 推进中国青少年消极身体意象本土化研究。 相似文献
129.
注意捕获是指与任务无关的刺激能够不自觉地吸引注意的现象。实验一采用视觉搜索任务,考察与主任务无关的情绪面孔的注意捕获水平及其机制,实验二进一步探究时间任务需求对无关情绪面孔注意捕获的影响。结果发现:与其他情绪面孔相比,愤怒的情绪面孔捕获了更多的注意,且受到整体情绪加工的影响;时间任务需求影响了目标刺激的注意选择,但愤怒优势效应不受到时间任务需求的影响,因此可能是一种较为自动化的加工过程。 相似文献
130.
人们喜欢关注道德事件并表达自己的立场。以往研究发现回忆自己(而非他人)的道德行为能影响个体的道德自我知觉和道德行为。本研究关注参与道德评价是否会对个体的道德自我和道德行为产生影响。2个研究共同发现:(1)存在道德“沾光”效应:评价支持他人的道德事件,或反对他人的不道德事件,能提升个体的道德自我知觉;(2)道德评价通过提升道德自我知觉,进一步增加个体的道德行为。 相似文献