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   38163篇
  免费   659篇
  国内免费   4篇
  38826篇
  2020年   457篇
  2019年   498篇
  2018年   617篇
  2017年   639篇
  2016年   749篇
  2015年   548篇
  2014年   664篇
  2013年   3090篇
  2012年   1165篇
  2011年   1169篇
  2010年   811篇
  2009年   822篇
  2008年   1151篇
  2007年   1069篇
  2006年   966篇
  2005年   889篇
  2004年   888篇
  2003年   855篇
  2002年   861篇
  2001年   853篇
  2000年   869篇
  1999年   640篇
  1998年   426篇
  1997年   379篇
  1992年   580篇
  1991年   566篇
  1990年   564篇
  1989年   556篇
  1988年   522篇
  1987年   524篇
  1986年   531篇
  1985年   580篇
  1984年   518篇
  1983年   464篇
  1982年   372篇
  1981年   426篇
  1979年   539篇
  1978年   422篇
  1977年   369篇
  1976年   365篇
  1975年   470篇
  1974年   532篇
  1973年   541篇
  1972年   441篇
  1971年   440篇
  1970年   395篇
  1969年   414篇
  1968年   510篇
  1967年   486篇
  1966年   455篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
Continuous causation, in which incremental changes in one variable cause incremental changes in another, has received little attention in the causal judgment literature. A video game was adapted for the study of continuous causality in order to examine the novel cues to causality that are present in these paradigms. The spatial proximity of an object to an "enemy detector" produced auditory responses as a function of the object's proximity. Participants' behavior was a function of the range of the effect's auditory sensitivity and the moment-to-moment likelihood of detection. This new paradigm provides a rich platform for examining the cues to causation encountered in the learning of continuous causal relations.  相似文献   
922.
Contemporary models of ADHD hypothesize that hyperactivity reflects a byproduct of inhibition deficits. The current study investigated the relationship between children's motor activity and behavioral inhibition by experimentally manipulating demands placed on the limited-resource inhibition system. Twenty-two boys (ADHD = 11, TD = 11) between the ages of 8 and 12 years completed a conventional stop-signal task, two choice-task variants (no-tone, ignore-tone), and control tasks while their motor activity was measured objectively by actigraphs placed on their nondominant wrist and ankles. All children exhibited significantly higher activity rates under all three experimental tasks relative to control conditions, and children with ADHD moved significantly more than typically developing children across conditions. No differences in activity level were observed between the inhibition and noninhibition experimental tasks for either group, indicating that activity level was primarily associated with basic attentional rather than behavioral inhibition processes.  相似文献   
923.
924.
Webster MA  Kay P 《Cognition》2012,122(3):375-392
We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary were perceptually exaggerated. This task did not require overt judgments of the perceived colors, and the tendency to group showed only a weak and inconsistent categorical bias. In a second case, we analyzed results from two prior studies of hue scaling of chromatic stimuli (De Valois, De Valois, Switkes, & Mahon, 1997; Malkoc, Kay, & Webster, 2005), to test whether color appearance changed more rapidly around the blue-green boundary. In this task observers directly judge the perceived color of the stimuli and these judgments tended to show much stronger categorical effects. The differences between these tasks could arise either because different signals mediate color grouping and color appearance, or because linguistic categories might differentially intrude on the response to color and/or on the perception of color. Our results suggest that the interaction between language and color processing may be highly dependent on the specific task and cognitive demands and strategies of the observer, and also highlight pronounced individual differences in the tendency to exhibit categorical responses.  相似文献   
925.
The present study focuses on how patients diagnosed with psychosis deal with a conflicting situation. In the study, two groups of patients were assessed. One group consisted of patients diagnosed with psychosis (n = 41), while the comparison group (n = 135) consisted of inpatients diagnosed either with anorexia nervosa or with bulimia nervosa. The groups were assessed using the Serial Color Word Test (S-CWT), designed for studying an individual's successive adaptation over time to a conflicting situation. The S-CWT differentiated the two groups regarding both reading time and adaptive styles. Patients diagnosed with psychosis had longer reading times and an adaptive style that was deviant throughout the test, indicating poorer cognitive functioning and more serious psychopathology. These problems may in turn influence functioning in work or study and daily living, all of which are important in treatment planning.  相似文献   
926.
Effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity [0 degrees (isometric)], 50 degrees, 100 degrees, 200 degrees, and 400 degrees/sec. [isovelocities]) on root mean square amplitude (SEMG-RMS) and median frequency power spectrum (SEMG-MNF) of vastus lateralis (VL) surface electromyography was investigated with ten healthy female university students. Peak torque (PT), mean torque (MT), SEMG-MNF, and SEMG-RMS, analyzed using separate repeated-measures analyses of variance (p < or = .05), indicated: (1) an inverse relation between PT and MT and movement velocity, (2) greater SEMG-MNF values during all isovelocity conditions compared with isometric conditions, with highest values occurring at 50 degrees /sec. and at 100% and 75% MVC, and (3) at all contraction intensities SEMG-RMS values were higher during dynamic movements than isometric movements and highest at 200 degrees /sec. Isovelocity contractions were inferred to facilitate a greater recruitment of fast-twitch fibers (via increased SEMG-MNF), which was intensified at 50 degrees /sec., whereas greater overall muscle activation was found at 200 degrees /sec.  相似文献   
927.
Childhood characteristics are associated with life-course-persistent antisocial behavior in epidemiological studies in general population samples. The present study examines this association in an inpatient sample. The purpose is to identify easily measurable childhood characteristics that may guide choice of treatment for adolescent psychiatric inpatients with severe disruptive behavior. Patients (N?=?203) were divided into two groups with either early-onset (EO) or adolescent-onset (AO) disruptive behavior, based on ages at which professional care was used for disruptive behavior, referral to special education, and criminal offences. Both groups differed on several childhood characteristics. No gender differences in these characteristics were found. Logistic regression analysis indicated that individuals with grade retention in primary school, childhood impulsive behavior, and a history of physical abuse, had the highest probability of being member of the EO group. These characteristics are reasonably easy to identify, likely apply to other clinical samples as well, and may help clinicians to target their treatment.  相似文献   
928.
Tripping and falling is a serious health problem for older citizens due to the high medical costs incurred and the high mortality rates precipitated mostly by hip fractures that do not heal well. Current falls prevention technology encompasses a broad range of interventions; both passive (e.g., safer environments, hip protectors) and active (e.g., sensor-based fall detectors) which attempt to reduce the effects of tripping and falling. However the majority of these interventions minimizes the impact of falls and do not directly reduce the risk of falling. This paper investigates the prediction of gait parameters related to foot-to-ground clearance height during the leg swing phase which have been physically associated with tripping and falling risk in the elderly. The objective is to predict parameters of foot trajectory several walking cycles in advance so that anticipated low foot clearance could be addressed early with more volitional countermeasures, e.g., slowing down or stopping. In this primer study, foot kinematics was recorded with a highly accurate motion capture system for 10 healthy adults (25-32 years) and 11 older adults (65-82 years) with a history of falls who each performed treadmill walking for at least 10 min. Vertical foot displacement during the swing phase has three characteristic inflection points and we used these peak values and their normalized time as the target prediction values. These target variables were paired with features extracted from the corresponding foot acceleration signal (obtained through double differentiation). A generalized regression neural network (GRNN) was used to independently predict the gait variables over a prediction horizon (number of gait cycles ahead) of 1-10 gait cycles. It was found that the GRNN attained 0.32-1.10 cm prediction errors in the peak variables and 2-8% errors in the prediction of normalized peak times, with slightly better accuracies in the healthy group compared to elderly fallers. Prediction accuracy decreased linearly (best fit) at a slow rate with increasing prediction horizon ranging from 0.03 to 0.11 cm per step for peak displacement variables and 0.34 × 10(-3) - 1.81 × 10(-3)% per step for normalized peak time variables. Further time series analysis of the target gait variable revealed high autocorrelations in the faller group indicating the presence of cyclic patterns in elderly walking strategies compared to almost random walking patterns in the healthy group. The results are promising because the technique can be extended to portable sensor-based devices which measure foot accelerations to predict the onset of risky foot clearance, thus leading to a more effective falls prevention technology.  相似文献   
929.
This article analyses the recent changes in modern society (??second modernity??) and their importance for criminological questions. These changes increase the risk of biographical crises of individuals which can result in the committing of crimes. Therefore, a review of the diagnostic and prognostic system of ??applied criminology?? was necessary. As a result the ??applied criminology?? had to be adapted and a new biographical type of ??crime in crises?? was deduced from this review. The value orientation and individual relevant aspects, for example special places, persons or strong interests, play a key role in appraising the new biographical type of ??crime in crises??. This new type fits to the developments of the second modernity and completes the system of ??applied criminology??.  相似文献   
930.
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