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   11992篇
  免费   319篇
  国内免费   3篇
  2021年   92篇
  2020年   136篇
  2019年   120篇
  2018年   301篇
  2017年   269篇
  2016年   397篇
  2015年   255篇
  2014年   223篇
  2013年   790篇
  2012年   588篇
  2011年   599篇
  2010年   242篇
  2009年   234篇
  2008年   343篇
  2007年   353篇
  2006年   303篇
  2005年   1557篇
  2004年   899篇
  2003年   695篇
  2002年   391篇
  2001年   166篇
  2000年   118篇
  1999年   152篇
  1998年   116篇
  1997年   113篇
  1996年   97篇
  1995年   90篇
  1994年   89篇
  1993年   86篇
  1992年   120篇
  1991年   132篇
  1990年   132篇
  1989年   98篇
  1988年   86篇
  1987年   104篇
  1986年   106篇
  1985年   106篇
  1984年   95篇
  1983年   94篇
  1982年   68篇
  1981年   81篇
  1980年   71篇
  1979年   108篇
  1978年   84篇
  1977年   81篇
  1976年   79篇
  1975年   87篇
  1974年   104篇
  1973年   82篇
  1966年   62篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Twenty six clinically healthy smokers were studied with transient pattern visual-evoked potentials. In comparison with a sample of "normal" subjects we found a difference of some parameters (P less than 0.05): the P2-latency and the interocular difference of latency on average were 6-7 ms respectively 2 ms larger. Thirteen subjects have had a prolonged P2-latency (P less than 0.05) and/or a difference in interocular latencies larger than 5 ms. These findings may suggest on subclinical disturbances of visual system and indicators of an special sensitivity of that person. The findings are possibly related to tobacco-alcohol amblyopia.  相似文献   
112.
In this paper, we shall confine ourselves to the study of sentential constants in the system R of relevant implication.In dealing with the behaviour of the sentential constants in R, we shall think of R itself as presented in three stages, depending on the level of truth-functional involvement.  相似文献   
113.
114.
Mothers' and fathers' responses on the Personality Inventory for Children (PIC) were compared for 360 clinic-referred children and adolescents. Interparent agreement was measured by several different indices. Correlations between parental pairs of scale T-scores derived from each parent averaged .66 for 13 of the profile scales; 9 of the scales exceeded this value. In contrast, mothers and fathers agreed in the classification of the presence of clinical significance an average of 77% of the time across these 13 scales, and pairs of parental PIC profiles contained an average of 3 scales in disagreement. The type of index used to measure interparent agreement was found to affect the results. The discussion examines the nature of interparent disagreement and addresses the implications regarding the use of fathers as informants on this instrument.This article is based on Thomas A. Hulbert's master's thesis. The authors extend their appreciation to James Orisell and Dena Mussaff for their assistance in data preparation and analysis.  相似文献   
115.
Pupillary responses have proven to be reliable physiological correlates of cognitive effort in a variety of tasks, including language processing. To investigate the relation between psychological and syntactic complexity 20 syntactically ambiguous sentences, balanced for bias, were presented to 16 subjects, while their pupil size was continuously measured. These sentences could be read as verb oriented (syntactically more complex) or object oriented (syntactically less complex). Principal components analysis of pupillary movements revealed that verb-oriented readings, resulted in greater pupillary dilations than object-oriented readings, indicating that syntactically more complex sentences, as determined via a formal grammar, require greater cognitive effort in processing. This is viewed as further evidence for the notion that syntactic and psychological complexity are related. High- and low-bias sentences did not induce comparable differences in pupillary movements, indicating that the "multiple meaning theory" may have to be modified.  相似文献   
116.
Aged rats with extensive prior training on the radial maze retain the capacity for accurate spatial working memory (WM) for at least 3 months without practice. To investigate the temporal limits of this influence of prior experience we compared the reacquisition of spatial WM by a group of experienced 21.5-month-old rats to the original acquisition by naive 3-month-old rats. The aged rats had received 225 radial maze tests between 3 and 11 months of age. Despite 10 months without practice the old rats rapidly reacquired critical performance. Their reacquisition was markedly superior to original learning by the young rats, even when delays as long as 5 h were imposed between the rats' fourth and fifth choices during the daily tests in the eight-arm maze. Additional tests showed that neither young nor old rats employed a response strategy to maintain accurate spatial WM performance. Experience clearly confers long-lived protection against the otherwise deleterious effects of aging on spatial WM, but the mechanism by which this influence arises is unknown.  相似文献   
117.
Children receiving 1 year or 1/2 year of a preventive social problem solving program in elementary school were compared with each other and with a no-treatment group upon entry into middle school. One year of training was significantly related to reductions in the severity of a variety of middle-school stressors. Most importantly, a clear mediating role for social problem solving (SPS) skills was found. Children lacking in SPS skills were more likely to experience intense stressors; however, possessing the skills was not necessarily predictive of adjustment to stressors. The results are discussed in terms of the implications of this asymmetry and the strong support given to the value of social problem solving as a preventive intervention for children.  相似文献   
118.
The ability to think of a previously studied item has often been shown to be impaired when, in one way or another, the extraitem context is changed from study to test. In a series of five experiments, such impairment is induced in a somewhat different way. A fragment (e.g. r-i--rop) of a just-studied word (raindrop) is shown to be less readily completed if it is presented bit by bit (r------p, r----r-p, r-i--r-p, r-i--rop) rather than all at once (Experiments 1, 3, 4, and 5). No such effect is found if the word has not been studied beforehand (Experiments 2, 3, 4, and 5). This pattern of results occurs even when fragments of studied and nonstudied words occur in the same test and under conditions in which subjects cannot tell whether a given fragment is of a studied or nonstudied word (Experiments 4 and 5). In addition, for words that have been studied beforehand, the impairment is shown to increase systematically with the number of steps involved in the presentation of the word fragment (Experiment 3) and also to persist when the time allowed for completion of the final version of the fragment is increased from 4 s to a full minute (Experiment 5).  相似文献   
119.
This clinical and theoretical overview of the right to refuse treatment will address some of the themes that have dominated this area of interface between psychiatry and the law, and have, perhaps, obscured the real concern of the right to refuse treatment question; i.e., the issue of quality of care. Central themes include factors present in the medicolegal context and recent events, origin of the concept of the right to treatment, the separation of confinement from treatment, and the changing models of vicarious decision making. This review also addresses judicial conceptualizations of treatment, including the concept of quarantine, judicial risk-aversiveness, and judicial fantasies of drug action. Some possible directions for the future are also examined.  相似文献   
120.
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