首页 | 本学科首页   官方微博 | 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   174642篇
  免费   7853篇
  国内免费   158篇
  182653篇
  2021年   1491篇
  2020年   2775篇
  2019年   3427篇
  2018年   3543篇
  2017年   3984篇
  2016年   4616篇
  2015年   3917篇
  2014年   4791篇
  2013年   23456篇
  2012年   4605篇
  2011年   3763篇
  2010年   3901篇
  2009年   4774篇
  2008年   3908篇
  2007年   3496篇
  2006年   4113篇
  2005年   4083篇
  2004年   3570篇
  2003年   3178篇
  2002年   3033篇
  2001年   3305篇
  2000年   3106篇
  1999年   3114篇
  1998年   2837篇
  1997年   2664篇
  1996年   2584篇
  1995年   2414篇
  1994年   2387篇
  1993年   2335篇
  1992年   2579篇
  1991年   2438篇
  1990年   2273篇
  1989年   2226篇
  1988年   2197篇
  1987年   2233篇
  1986年   2193篇
  1985年   2451篇
  1984年   2527篇
  1983年   2337篇
  1982年   2396篇
  1981年   2362篇
  1980年   2189篇
  1979年   2228篇
  1978年   2195篇
  1977年   2153篇
  1976年   1968篇
  1975年   2020篇
  1974年   2065篇
  1973年   1972篇
  1972年   1541篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Two experiments are reported which investigated how subject gender and time-of-day influenced the estimation of duration and the perception of task-related mental workload. In the first experiment, 24 subjects performed a filled time-estimation task in a constant blacked-out, noise-reduced environment at 0800h, 1200h, 1600h, and 2000h, respectively. In the second experiment, 12 different subjects performed an unfilled time estimation task in similar conditions at 0900h, 1400h, and 1900h. At the termination of all experimental sessions, participants completed the NASA Task Load Index workload assessment questionnaire as a measure of perceived mental workload. Results indicated that physiological response, reflected in body temperature change, followed an expected pattern of sequential increase with time-of-day. However, estimates of duration and the perception of mental workload showed no significant effects for time-of-day. In each of the experiments there were significant differences in time estimation and mental workload response contingent on the gender of the participant. These results are interpreted in light of the previous positive findings for circadian fluctuation in performance efficiency and the equivocal findings of a gender difference in time estimation. A unifying account of these collective results is given based on gender by time-of-day interactional effects. An earlier version of this paper was presented at the 32nd Annual Meeting of the Human Factors Society, Anaheim, CA, October, 1988.  相似文献   
972.
973.
This exploratory study sought to determine whether selected religion-related factors differentiated between 86 patients with obsessive compulsive disorder (OCD), 73 patients with panic disorder, and 292 patients with other psychiatric (non-anxiety) disorders. A standard history questionnaire was used to obtain information from patients concerning religion of origin, involvement in religious activities, religious conflict, and perceived religiousness of parents. It was found that the percentage of patients who reported experiencing religious conflict was significantly higher for the OCD group than for the other two groups. Other findings suggested associations between Catholicism and OCD and between Protestantism and panic disorder, but further research is needed to clarify these relationships. This article is based on a paper presented at the 98th annual convention of the American Psychological Association, Boston, August 1990.  相似文献   
974.
975.
Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.  相似文献   
976.
Despite considerable experimental work on Alzheimer's disease (AD), the underlying cognitive mechanisms as well as the precise localization of neuropathological changes critical for memory loss remains undefined. A review of the neuropsychological literature on long-term memory deficits in AD patients suggests that AD patients display (a) a pervasive deficit of explicit memory, (b) a partial deficiency of implicit memory for verbal and visuoperceptual material (as measured by repetition priming procedures), and (c) a substantial sparing of implicit memory for visuomotor skills. The explicit memory loss is likely a result of encoding as well as consolidation difficulties. A faulty lexical-semantic knowledge structure appears responsible for deficient repetition priming effects. Since neuropathological changes diffusely affect the brain of AD patients, establishing a clear relationship between localization of cerebral lesions and memory deficits is particularly difficult. Nevertheless, data suggest that extensive involvement of the hippocampal-amygdala complex plays a major role in explicit memory loss. Damage to associative cortical areas likely is involved in repetition priming deficits. The relative integrity of primary motor and sensory cortical areas and of the basal ganglia likely subsume, by contrast, the normal learning of visuomotor skills.  相似文献   
977.
This article contains detailed reviews of 13 computerized neuropsychological and performance test batteries and six stand-alone computer tests. Tasks found on these instruments are described and tables illustrate which batteries employ which measures. In addition to issues of reliability and validity, special considerations apply to computerized assessment. These issues are discussed and readers are provided information to help them assess computerized tests in relation to their particular clinical and research needs. Since many computerized tests were developed as performance assessment tools, the relationship between performance and neuropsychological assessment is examined.  相似文献   
978.
979.
Recently, debate about the distribution of scarce organs for transplantation has focused on whether patients should have the right to place themselves on waiting lists at several transplant centers, thereby gaining an advantage over other potential recipients. This article explores the social and ethical issues raised by multiple listing, contrasting policies adopted at the national level with those implemented in New York State. It concludes by examining the implications of the debate for broader questions about entitlement and access to health care.  相似文献   
980.
With increasing momentum for health care reform, attention is shifting to finance reform that will provide for direct methods for controlling health care spending. This article outlines the two principal paths to direct cost control and outlines a national plan that retains our multiple sources of payment, yet also contains a powerful direct cost control technique: a single fund to finance all health care.  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