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   50717篇
  免费   1956篇
  国内免费   28篇
  52701篇
  2019年   638篇
  2018年   887篇
  2017年   953篇
  2016年   951篇
  2015年   714篇
  2014年   795篇
  2013年   3992篇
  2012年   1404篇
  2011年   1538篇
  2010年   974篇
  2009年   955篇
  2008年   1321篇
  2007年   1307篇
  2006年   1183篇
  2005年   1041篇
  2004年   960篇
  2003年   1001篇
  2002年   973篇
  2001年   1798篇
  2000年   1744篇
  1999年   1272篇
  1998年   560篇
  1997年   475篇
  1996年   488篇
  1992年   1077篇
  1991年   1044篇
  1990年   996篇
  1989年   939篇
  1988年   928篇
  1987年   892篇
  1986年   870篇
  1985年   939篇
  1984年   742篇
  1983年   614篇
  1982年   472篇
  1981年   478篇
  1979年   769篇
  1978年   563篇
  1977年   508篇
  1976年   486篇
  1975年   651篇
  1974年   737篇
  1973年   793篇
  1972年   637篇
  1971年   577篇
  1970年   553篇
  1969年   548篇
  1968年   691篇
  1967年   616篇
  1966年   636篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
944.
DETERMINANTS OF R AND D COMPENSATION STRATEGIES IN THE HIGH TECH INDUSTRY   总被引:1,自引:0,他引:1  
This study indicates that sales volume, stage in the product life cycle, profitability and turnover are all important predictors of the method and magnitude of financial rewards provided by high tech firms to R and D employees. The most favorable situational factors for R and D incentive compensation are a low sales volume high tech company, operating in the growth stage of the product life cycle, with high turnover rates, and capable of linking profitability to incentive rewards such as bonuses.  相似文献   
945.
The intention of this study was to improve behavioral modeling's effectiveness by substituting managers for professional trainers and to evaluate the effect on 44 male supervisors using Kirkpatrick's four levels of evaluation: reaction, learning, behavior on the job, and performance. Twenty-two supervisors were trained with six behavior modeling modules and the effect was compared to a control group consisting of 22 supervisors. The research also examined the effects of trainees’ self-esteem and the perceived power of the trainers. The results showed that behavior modeling resulted in favorable reactions and an increase in learning, but did not produce behavior change on the job, or improved performance results. Power and self-esteem did not moderate the training effectiveness. The findings are compared with previous behavior modeling research. The discussion concludes with a recommendation for researchers to identify more complete theoretical models which explain behavioral change on the job (e.g., Maltz's theory of psycho-cybernetics) as opposed to relying solely on Bandura's social learning theory.  相似文献   
946.
The peak amplitude of EMG activity was measured from the orbicularis oris superior (OOS), orbicularis oris inferior (OOI) and masseter muscles for 3 normal 4-yr.-old children and compared to past data gathered on a group of articulatory disordered children, normal children, and adults. The 4-yr.-olds evidenced greater average peak EMG activity than the other groups, suggesting that speech-sound production becomes more efficient with maturation. Also, levels of variability obtained for the younger children were considerably smaller than for the normal speakers across the three muscles, showing that motor equivalence changes with age whereby the flexibility in the control of articulators increases. The coefficient of variation for the OOI muscle for the disordered children, however, was similar to that for the 4-yr.-olds, while the corresponding data for the other two muscles paralleled those for normal ones. These findings were interpreted as reflecting a delay in the development of speech-motor equivalence that affects certain muscles while sparing others.  相似文献   
947.
Golden hamsters are able to detect differences in the height of a platform from which they jump, as measured by their increasing latencies prior to jumping from increased elevations. This ability is very effective when optical information is available, but it is also present when hamsters jump in total darkness. A second experiment shows that, when hamsters are placed on a real physical cliff, they preferentially use tactile information over visual information to guide their choice of the side from which to descend. In a nonvisual setting, tactile stimulation is used in conjunction with other types of cues. Evidence is provided to suggest that these cues are of an acoustical nature.  相似文献   
948.
This experiment concerned the contribution of polydipsia on the temporal discrimination of rats during a fixed-interval 60-sec. schedule. In this study, the timing accuracy of 12 rats which had access to water during training was compared to that of 12 rats which had no water during training. The rats were trained for 25 sessions on an FI 60-sec. schedule. In early sessions before polydipsia was fully developed, no differences existed between the timing accuracy of the water group and no-water group. As the amount of water drunk by the water group increased as the number of sessions increased, a parallel increase was noted in the timing accuracy of the water group. In the final sessions, a significant difference was found between the timing accuracy of rats in the water group and that of those in the no-water group. It was concluded that polydipsia facilitated the development of the temporal discrimination which is characteristic of a fixed-interval 60-sec. schedule.  相似文献   
949.
This study was designed to determine possible differences in the cognitive, perceptual, and personal-social development of prematurely and maturely born 3-yr.-olds which might foreshadow later learning problems. The subjects were 40 prematurely born graduates of a neonatal intensive care unit (birth weight less than 2,500 gm, less than 37 wk. gestation) matched on the pair-level with full-term controls on sex, race, post-conceptual age, and socioeconomic background. All subjects were singletons and parity was matched at the group level. No differences were found between the groups on tests of higher mental processes including the General Cognitive, Verbal, Quantitative, and Memory Scales of the McCarthy Scales of Children's Abilities, and researcher-devised measures of problem-solving competence. No differences in parental reports of personal-social development were noted. Prematures did not perform as well as controls on perceptual performance tasks, and this difference was interpreted as reflecting relatively impaired visual-motor coordination.  相似文献   
950.
40 schizophrenic subjects, divided into paranoid/non-paranoid categories and 14 normal controls were presented a task which involved making "same-different" judgments during random presentations of a series of visual comparison stimuli with a standard which represented the midpoint of the stimulus continuum. Using Sternberg's Choice RT paradigm for studying the locus of cognitive deficit, difficulty at the response-selection stage was manipulated while holding other stages constant. It was predicted that paranoids would have shorter RTs at easy decision points and longer RTs at difficult decision points relative to non-paranoids. The directions of the differences were as predicted but did not attain statistical significance. Both schizophrenic groups, compared to normals, made significantly fewer "same" responses on those trials where the comparison and standard were most similar.  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