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   52235篇
  免费   1003篇
  国内免费   5篇
  53243篇
  2020年   484篇
  2019年   657篇
  2018年   892篇
  2017年   961篇
  2016年   961篇
  2015年   729篇
  2014年   804篇
  2013年   4010篇
  2012年   1418篇
  2011年   1554篇
  2010年   993篇
  2009年   967篇
  2008年   1332篇
  2007年   1315篇
  2006年   1187篇
  2005年   1048篇
  2004年   973篇
  2003年   1006篇
  2002年   981篇
  2001年   1804篇
  2000年   1752篇
  1999年   1279篇
  1998年   572篇
  1997年   481篇
  1996年   490篇
  1992年   1080篇
  1991年   1049篇
  1990年   998篇
  1989年   941篇
  1988年   935篇
  1987年   896篇
  1986年   872篇
  1985年   943篇
  1984年   747篇
  1983年   620篇
  1981年   484篇
  1979年   772篇
  1978年   565篇
  1977年   509篇
  1976年   486篇
  1975年   656篇
  1974年   742篇
  1973年   796篇
  1972年   638篇
  1971年   577篇
  1970年   554篇
  1969年   550篇
  1968年   692篇
  1967年   618篇
  1966年   638篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
Three-way metric unfolding via alternating weighted least squares   总被引:6,自引:3,他引:3  
Three-way unfolding was developed by DeSarbo (1978) and reported in DeSarbo and Carroll (1980, 1981) as a new model to accommodate the analysis of two-mode three-way data (e.g., nonsymmetric proximities for stimulus objects collected over time) and three-mode, three-way data (e.g., subjects rendering preference judgments for various stimuli in different usage occasions or situations). This paper presents a revised objective function and new algorithm which attempt to prevent the common type of degenerate solutions encountered in typical unfolding analysis. We begin with an introduction of the problem and a review of three-way unfolding. The three-way unfolding model, weighted objective function, and new algorithm are presented. Monte Carlo work via a fractional factorial experimental design is described investigating the effect of several data and model factors on overall algorithm performance. Finally, three applications of the methodology are reported illustrating the flexibility and robustness of the procedure.We wish to thank the editor and reviewers for their insightful comments.  相似文献   
222.
223.
224.
Fear of death and the concept of extended self   总被引:1,自引:0,他引:1  
  相似文献   
225.
Plasma concentrations of imipramine and amitriptyline and their desmethylated metabolites were measured in 20 children being treated for major depressive illness 2 wk. and 5 to 10 wk. after achieving drug dosages of 2.25 mg/kg body weight. At 2 wk. all children had exhibited clinical improvement, but by 10 wk. 4 of the 10 children treated with imipramine and 5 of the 10 children treated with amitriptyline had experienced clinical relapse of depressive symptoms. Tricyclic antidepressant plasma concentrations and ratios were comparable in the subgroups of children who maintained their clinical improvement and those who relapsed. There was no evidence of a systematic decline in plasma tricyclic antidepressant concentrations in those children who relapsed.  相似文献   
226.
Tympanic thermometers were used to measure fluctuations in the temperature of the left and right hemispheres of 22 normal high school students while performing verbal and nonverbal visual discrimination tasks. The nonverbal task involving face recognition demonstrated the predicted effect of hemispheric bias on performance: The subjects performed better when they showed a relative rise in right-hemisphere temperature. No significant relationship between hemispheric temperature and level of performance was observed during the verbal task, perhaps owing to the opportunity to treat effectively the nonwords as either linguistic strings or visual patterns. It is concluded that tympanic temperature effectively measures hemispheric activity during cognitive processing.  相似文献   
227.
228.
The authors present a short review of the pertinent literature and report on their own neuropsychiatric findings following internal craniocerebral injuries, at the same time drawing attention to the necessity of psychological examination. Statistical comparisons with the international literature are complicated owing to the different classifications used for craniocerebral injuries.  相似文献   
229.
Microcomputer-assisted relaxation   总被引:1,自引:0,他引:1  
The present pilot study was designed to test the effectiveness of a microcomputer program developed by the authors to induce relaxation and focused attention, which are common to most clinical stress-reduction and hypnotic procedures. A nonclinical sample of 20 adults used the program on an APPLE IIc computer in two 30-min. sessions in a within-subjects design. Repeated measures analyses of variance showed significant decreases in the Spielberger State Anxiety Scale and on a visual analog anxiety scale. Limitations and implications of the study are discussed.  相似文献   
230.
This project studied the effects of weather variables and size of the population on minor and major violence rates within six prisons in the Kingston, Ontario, Canada area from January, 1980 through December, 1983. While weather variables have been studied in relation to mood changes within the general population, this study was the first to analyze the impact of weather variables on rates of violence within the prison setting using forward inclusion multiple regression. Analysis showed that population size consistently appeared positively correlated with assaults on other inmates among the male medium-security prisoners during the summer months. In the summer months, temperature tended to be positively related to some minor kinds of offenses, but in the winter months the relationship was negative. Humidity, rain, sunshine hours, snow, and snow on the ground were not consistently related to incidences of minor and major violence. Indices of geomagnetic disturbances had statistically significant inverse relationships with attempted suicide/self-inflicted injury rates among the male prisoners during the summer months. Over 12 months, wind was generally negatively correlated with incidences of major and minor violence among the male inmates. For 6-mo. periods, wind was generally positively correlated with violence rates during the winter months and negatively correlated during the summer months among the male inmates. The findings relating weather variables to violence rates in the women's prison were consistently in opposition to those found for male prisoners during the 4-yr. period.  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