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   17385篇
  免费   583篇
  国内免费   5篇
各国政治   686篇
工人农民   876篇
世界政治   1136篇
外交国际关系   575篇
法律   11127篇
中国共产党   7篇
中国政治   172篇
政治理论   3219篇
综合类   175篇
  2020年   250篇
  2019年   301篇
  2018年   384篇
  2017年   446篇
  2016年   443篇
  2015年   346篇
  2014年   356篇
  2013年   1639篇
  2012年   492篇
  2011年   549篇
  2010年   429篇
  2009年   455篇
  2008年   545篇
  2007年   569篇
  2006年   555篇
  2005年   499篇
  2004年   484篇
  2003年   515篇
  2002年   448篇
  2001年   690篇
  2000年   550篇
  1999年   486篇
  1998年   258篇
  1997年   178篇
  1996年   207篇
  1995年   176篇
  1994年   203篇
  1993年   197篇
  1992年   325篇
  1991年   356篇
  1990年   342篇
  1989年   281篇
  1988年   324篇
  1987年   275篇
  1986年   322篇
  1985年   284篇
  1984年   233篇
  1983年   229篇
  1982年   180篇
  1981年   193篇
  1980年   128篇
  1979年   172篇
  1978年   122篇
  1977年   109篇
  1976年   98篇
  1975年   123篇
  1974年   132篇
  1973年   105篇
  1972年   100篇
  1969年   98篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
964.
The first aim of this study was to examine the structure of externalizing and internalizing problem behavior during early adolescence. Our second aim was to determine the stability of these problems for boys and for girls over time. A total of 650, 13–14-year-olds filled out (an expanded version of) the Youth Self-Report [YSR; Manual for the Youth Self-Report and 1991 Profile. Department of Psychiatry, University of Vermont, Burlington] 2 times with a 1-year interval. By using confirmatory factor analyses (CFA) to test a series of competing models, a hierarchical model provided the best representation of the structure of problem behavior at both Time 1 and Time 2: externalizing and internalizing problem behavior represent distinct aspects but the model also demonstrates the existence of comorbidity at a higher level. This model appeared to be stable over time for both boys and girls. The relative stability of problem behavior was found to be high for boys and girls. Absolute stability for both externalizing and internalizing problems appeared to be higher for boys scoring in the lower range of problem behavior. Senior Researcher, Utrecht University, The Netherlands. Received PhD in social sciences, University of Amsterdam. Major research interests include problem behavior, family relations, and peer relations during adolescence. Full Professor, Utrecht University, The Netherlands. Received PhD in social sciences: child and family studies, from University of Nijmegen. Major research interests include adolescent social development, problem behavior, and family relations during adolescence. Assistant Professor, University of Amsterdam, The Netherlands. Received PhD in psychology, University of Amsterdam. Major research interests include family influence on childhood illness and problem behavior.  相似文献   
965.
966.
967.
The human teeth are a valuable source of information concerning identification and age calculation in forensic sciences. Dental treatment often causes permanent alteration of the teeth, which is visible on radiographs. The correlation of prosthetic restorations, root canal fillings and periodontal bone loss with chronological age has not yet been used for determining the completed 18th year of life in teenagers and young adults, e. g. for legal and anthropological purposes. The aim of this study was to determine whether the evaluation of such findings on radiographs correlates with the chronological age in teenagers and young adults. MATERIAL AND METHODS: The dental X-rays (orthopantomogram, OPG) of 1053 outpatients (age: 14 to 24 years) were avaluated. The values "prosthetically restored", "filled dental root", or "periodontal bone loss" were recorded for each tooth present. The data were then evaluated using statistical tools. RESULTS: The correlation between the number of prosthetically restored teeth and the chronological age is high. The positive predictive value of determining an age of at least 18 years proved to be very high. However, these findings are rarely present in this age group. The number of endodontically treated teeth correlated less exactly with age. On the other hand, the determination of periodontal bone loss gave reasonable positive predictive values for the threshold value "chronological age of 18 years or more". DISCUSSION: This study provides for the first time predictive values for the estimation whether a person is 18 years of age, based on the evaluation of teeth with prosthetic restorations, root canal fillings or periodontal bone loss on OPGs only. Whereas the number of patients with such findings is generally low in this age group, some of the positive findings can be used for age estimation as an adjunct to other sources of age calculation. The sole application of these criteria is not recommended, as sanitary conditions of the teeth depend on both social and individual circumstances. Therefore, the calculated values also reflect the culture of the sample studied. Finally, they are time-dependent and have to be compared to data from other populations. These results have some bearing on the field of forensic odontology.  相似文献   
968.
969.
Ehlers-Danlos Syndrome Type IV is an illness that often leads to premature death due to arterial rupture or dissection and is characterized by very fragile connective tissue. This report documents the death of a 30-year-old man with Ehlers-Danlos Syndrome Type IV from myocardial rupture and cardiac tamponade following a myocardial infarction. We believe that Ehlers-Danlos Syndrome Type IV contributed to the coronary atherosclerosis and myocardial rupture in this young man and that this disease led indirectly to his death by myocardial infarction, an unusual cause of death in this syndrome.  相似文献   
970.
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