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   37318篇
  免费   1450篇
  国内免费   22篇
  2020年   398篇
  2019年   471篇
  2018年   658篇
  2017年   678篇
  2016年   712篇
  2015年   506篇
  2014年   649篇
  2013年   3184篇
  2012年   1147篇
  2011年   1220篇
  2010年   790篇
  2009年   767篇
  2008年   1133篇
  2007年   1074篇
  2006年   1057篇
  2005年   937篇
  2004年   898篇
  2003年   916篇
  2002年   925篇
  2001年   864篇
  2000年   845篇
  1999年   709篇
  1998年   440篇
  1997年   462篇
  1996年   447篇
  1995年   411篇
  1992年   618篇
  1991年   589篇
  1990年   569篇
  1989年   533篇
  1988年   514篇
  1987年   509篇
  1986年   570篇
  1985年   574篇
  1984年   525篇
  1983年   461篇
  1981年   399篇
  1979年   500篇
  1978年   429篇
  1977年   378篇
  1976年   389篇
  1975年   427篇
  1974年   522篇
  1973年   542篇
  1972年   391篇
  1971年   408篇
  1969年   399篇
  1968年   459篇
  1967年   424篇
  1966年   439篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The present study investigated the relationship between performance goal orientation and performance on a complex task. It was hypothesized that cognitive interference would mediate this relationship. In addition, it was hypothesized that cognitive ability would moderate the relationship between cognitive interference and task performance. A three-variable suppressor relationship indicated that, although the direct effect of performance goal orientation on performance was one that produced better performance, the indirect effect of performance goal orientation indicated that performance orientations were associated with increases in cognitive interference, and these increases in cognitive interference were associated with poorer performance. Thus, the beneficial aspect of performance goal orientation (i. e., the direct effect) was counterbalanced by the dysfunctional aspects of performance goal orientation (i. e., the associated increase in cognitive interference). Support was also found for the proposed moderation of ability on the cognitive interference-task performance relationship for final, but not initial performance. The results are interpreted in light of recent discussions regarding the influence of goal orientation on task performance and cognitive interference.  相似文献   
992.
The Family Factors Field Study of Operation Desert Shield/Storm (ODS) was designed to collect data on the impact of the Persian Gulf deployment on soldier/family well-being, and the effectiveness of Army and community resources in assisting and supporting families of deployed soldiers. In October 1990, a task force was assembled, and multi-agency research teams visited several Army installations. Informal individual and group interviews were conducted with spouses, unit family support leaders, unit rear detachment personnel, garrison leaders, and local Army program/service providers. The questions were aimed at identifying key stressors which spouses and children experienced in relation to the sudden deployment, as well a stress mediators such as social supports and personal coping skills. Anecdotal information collected during the site visits, combined with findings from previous research on Army families, was used to develop a questionnaire designed to quantify those variables which emerged as relevant to a study of stressors and stress mediators in the context of the ODS deployment.  相似文献   
993.
A proximal-distal theoretical framework was developed to examine the multivariate roots of homophobia. Using data from a sample of 288 undergraduates who had participated in a computer-assisted panel study over a three-year period, the effects on homophobia of distal and proximal family factors (e. g., parental education and family environment), distal and proximal individual factors (e. g., personality constructs and current beliefs), and proximal individual-situational factors (e. g., acquaintance with homosexuals) were tested in regression analyses. Both analyses employing sets of variables varying in proximity to the homophobic attitude and hierarchical regression employing variables contributing significantly in each set supported the proposed framework. All sets predicted significantly when regressed separately on homophobia; the sets containing the distal factors contributed most weakly, and the sets containing the proximal factors contributed most strongly. In hierarchical regression analysis, this pattern maintained such that the incremental increase in r2 decreased with the addition of each more distal set, with the most distal factors failing to contribute significantly to the prediction. The importance of study findings for attitude change efforts is discussed.  相似文献   
994.
Three mildly malnourished children with cystic fibrosis and their parents participated in a behavioral group-treatment program that focused on promoting and maintaining increased calorie consumption. Treatment included nutritional education, gradually increasing calorie goals, contingency management, and relaxation training, and was evaluated in a multiple baseline design across four meals. Children's calorie intake increased across meals, and total calorie intake was 32% to 60% above baseline at posttreatment. Increased calorie consumption was maintained at the 96-week follow-up (2 years posttreatment). The children's growth rates in weight and height were greater during the 2 years following treatment than the year prior to treatment. Increases in pace of eating and calories consumed per minute were also observed 1 year posttreatment. These findings replicated and extended earlier research supporting the efficacy of behavioral intervention in the treatment of malnutrition in children with cystic fibrosis.  相似文献   
995.
Child-to-parent transmission of cytomegalovirus may be reduced by increasing protective behaviors (handwashing and glove use) and decreasing risky behaviors (intimate contact between child and parent). This study showed that an educational intervention resulted in increases in reported and objective measures of protective behaviors and decreases in reported risky behaviors. Further study must determine if changes in protective and risky behavior are maintained and prevent cytomegalovirus transmission.  相似文献   
996.
An operant simulation of foraging through baited and empty patches was studied with 4 pigeons. On a three-key panel, side keys were designated as patches, and successive opportunities to complete 16 fixed-ratio 10 schedules on side keys were defined as encounters with feeders. In a random half of the patches in any session, some of the fixed-ratio 10 schedules yielded reinforcement (baited feeders) and the other schedules yielded nonreinforcement (empty feeders). In the other half of the patches, all feeders were empty. Pigeons could travel between patches at any time by completing a fixed-ratio schedule on the center key. An optimal foraging model was tested in Experiments 1 and 2 by varying center-key travel time and number of baited feeders in baited patches. The ordinal predictions that number of feeders visited in empty patches would increase with travel time and decrease as number of baited feeders increased were supported, but pigeons visited far more feeders in empty patches than the optimal number predicted by the model to maximize energy/time. In Experiment 3, evidence was found to suggest that the number of empty feeders encountered before the first baited feeder in baited patches is an important factor controlling leaving empty patches.  相似文献   
997.
998.
In this paper, we applied the behavioral-economic concept of unit price to the study of reinforcer magnitude in an attempt to provide a consistent account of the effects of reinforcer magnitude on behavior. Recent research in the experimental analysis of behavior and in behavioral pharmacology suggests that reinforcer magnitude interacts with the schedule of reinforcement to determine response rate and total consumption. The utility of the unit-price concept thus stems from its ability to quantify this interaction as a cost-benefit ratio (i.e., unit price = characteristics of the schedule of reinforcement divided by magnitude of reinforcement). Research employing the unit-price concept has shown that as unit price increases, a positively decelerating function exists for consumption (i.e., a function with an increasingly negative slope, when plotted on log coordinates) and a bitonic function exists for response rate. Based on these findings, the present analysis applied the unit-price concept to those studies of reinforcer magnitude and drug self-administration that examined the effects of reinforcer magnitude on response rate using simple schedules of reinforcement (e.g., fixed-ratio schedule). This resulted in three findings: (a) Reinforcer-magnitude manipulations and schedule manipulations interact in a manner that can be quantified in terms of unit price as benefit and cost factors, respectively; (b) different reinforcer-magnitude manipulations are functionally interchangeable as benefit factors in the unit-price ratio; and (c) these conclusions appear warranted despite the differences in reinforcers (food or drug), species (dogs, monkeys, or rats), and schedules (interval or ratio), and despite the fact that these studies were not designed for a unit-price analysis. In methodological terms, these results provide further evidence that employing the unit-price concept is a parsimonious method for examining the effects of reinforcer magnitude. In theoretical terms, these results suggest that a single process may underlie the effect of combined reinforcer-magnitude and schedule manipulations.  相似文献   
999.
It is shown that IRTs information function for an item is functionally related to local versions of classical test theories' signal/noise ratio and reliability coefficient.  相似文献   
1000.
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