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   3910篇
  免费   216篇
  国内免费   10篇
  2023年   47篇
  2022年   37篇
  2021年   45篇
  2020年   95篇
  2019年   100篇
  2018年   132篇
  2017年   132篇
  2016年   154篇
  2015年   73篇
  2014年   113篇
  2013年   447篇
  2012年   162篇
  2011年   195篇
  2010年   124篇
  2009年   114篇
  2008年   141篇
  2007年   168篇
  2006年   144篇
  2005年   125篇
  2004年   116篇
  2003年   113篇
  2002年   106篇
  2001年   75篇
  2000年   42篇
  1999年   48篇
  1998年   38篇
  1997年   38篇
  1996年   31篇
  1995年   48篇
  1994年   49篇
  1993年   35篇
  1992年   44篇
  1991年   44篇
  1989年   34篇
  1988年   37篇
  1987年   32篇
  1986年   35篇
  1985年   32篇
  1984年   28篇
  1983年   27篇
  1982年   28篇
  1981年   32篇
  1980年   27篇
  1979年   35篇
  1978年   48篇
  1977年   42篇
  1976年   27篇
  1975年   27篇
  1974年   29篇
  1973年   30篇
排序方式: 共有4136条查询结果,搜索用时 15 毫秒
61.
In matters of discontinuation of life-sustaining treatment, traditional role of the family to speak on behalf of the incompetent patient is questionable. We explore the reasons why physicians perceive patient autonomy to be transferrable to family members. Principle of patient autonomy may not suffice when futile treatment is demanded and may serve to erode the ethical integrity of medical profession. An enhanced role for bioethics committees is proposed when physicians propose to discontinue life-sustaining treatment against the wishes of the patient or their families.  相似文献   
62.
We examined the effects of a self-monitoring program on reducing the frequency of negative statements of a student with mild mental retardation who was enrolled in a self-contained classroom at a middle school. A changing criterion design was used within a multiple baseline design across two classroom periods. Additionally, the frequency of positive statements was reported. The results showed a decrease in the number of negative statements, and an increase in the number of positive statements. Maintenance data collected up to 8 weeks after the program ended indicated that the student continued to emit positive rather than negative statements. The use of this procedure to decelerate undesirable behavior is discussed.  相似文献   
63.
Tolbutamide has previously been shown to amplify the pressor effects of “exogenous” catecholamines in conscious dogs, possibly due to sensitization of the α1-adrenoreceptor-mediated vasoconstriction. The objective of this study was to examine if tolbutamide also amplifies the pressor effects of “endogenous” catecholamines released during psychological stress (classical Pavlovian aversive conditioning). Experiments were conducted in β-adrenoreceptor-blocked (propranolol, 1 mg/kg, i.v.) conscious dogs (n=4) trained in classical aversive conditioning. Conditioning was accomplished by following a tone (CS+) with a 1/2 second shock; another tone (CS-) was not followed by any shock and served as control. With saline pretreatment, aversive conditioning (i.e., CS+) increased mean arterial pressure (MAP) only by approximately 4.7% when compared to CS-, whereas with tolbutamide (45 mg/kg, i.v.) pretreatment, the increase in MAP induced by CS+ beyond what was induced by the CS- (approximately 6.2%) was significantly (p<0.05) larger than that with saline pretreatment. In isolated canine femoral arterial segments (n=4), the vasoconstrictor effect of phenylephrine (an α1-agonist) at 5×10?6M (which was the EC50 value) was amplified by 2×10?2M of tolbutamide from 54.0±2.0% to 66.9±2.1%. In conclusion, tolbutamide amplifies the pressor effects of “endogenous” catecholamines in conscious dogs, possibly by sensitization of the α1-adrenoreceptor-mediated vasoconstriction. This mechanism of action is novel and has not been reported with other agents.  相似文献   
64.
The substitutability of reinforcers   总被引:5,自引:3,他引:2       下载免费PDF全文
Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included.  相似文献   
65.
Previous research on popular images of women and of minority groups has looked almost solely at images of minority men and of white women. This article presents survey data on images of black women among 256 white non-Hispanic college undergraduates, using a modified Katz/Braly scale. The article explores the nature, distribution, correlates, and emotional evaluations of these images and the implications of these images for black women's lives. Images of black women differed substantially from those of American women in general. Most commonly, black women were characterized as loud, talkative, aggressive, intelligent, straightforward, and argumentative. In addition, students rated positive traits less positive and negative traits less negative when exhibited by black women than by American women in general, apparently because of their expectations for black women's behavior.This paper has benefited from the comments of Verna Keith, Wade Smith, and, most especially, Mary Benin. This research was partially supported by Arizona State University Women's Studies Summer Research Awards Program.  相似文献   
66.
67.
Some hypotheses concerning the evolution of polysemous words   总被引:1,自引:0,他引:1  
The evolution of polysemous words is examined in three studies. Study 1 indicates that older words are more polysemous than recent words, and that frequently used words are more polysemous than infrequently used words. These effects were replicated, controlling for word concreteness (Study 2) and evaluation (Study 3), using two other samples of words. If words evolve additional meanings through metaphor (MacCormac, 1985), then variables (such as concreteness and evaluation) that play a role in metaphor may mediate the evolution of polysemy. The correlation between concreteness and polysemy was negligible (Study 2). As hypothesized, evaluation is a significant predictor of polysemy: Negative words are more polysemous than positive words, and relatively neutral words are more polysemous than evaluatively extreme words. These findings are consistent with the notion that polysemous words evolve, in part, through metaphor.  相似文献   
68.
This study presents initial standardization data on the Sutter- Eyberg Student Behavior Inventory (SESBI), a teacher- completed measure of disruptive classroom behaviors. SESBIs were completed on 1116 children in kindergarten through fifth grade in a rural eastern Washington school district. Various analyses (Cronbach's alpha, corrected item- total correlations, average interitem correlations, principal components analyses) indicated that the SESBI provides a homogeneous measure of disruptive behaviors. Support was also found for three factors within the scale (e.g., overt aggression, oppositional behavior, and attentional difficulties). While the child's age did not have a significant effect on the SESBI, the child's gender did have a significant effect on scale scores as well as on most of the items, with males being rated more problematic than females. The SESBI was also able to discriminate between children in treatment for behavioral problems or learning disabilities and children not in treatment.The authors would like to acknowledge the support of the teachers in the Pullman School District, whose kind help and assistance made the study possible. Special thanks are also extended to Todd Sosna, Christine Ladish, and Lee Sternberger for their helpful comments on earlier versions of the paper. Preparation of this study was supported in part by funds provided to G. Leonard Burns by Washington State University.  相似文献   
69.
The study was part of an official project of the Women in Management Division of the Academy of Management to examine the status of research in gender issues in organizations. It specifically looked at 22 major scholarly and trade journals plus the Proceedings of the Academy of Management for the six-year period of 1983–1988 to determine quantity, patterns, and trends in publication of research on issues of interest to the domain of the division. Results show a downward trend in gender-issue publication at a time when working women are becoming an ever-increasing percentage of the work force. This is particularly true of the so-called prestige journals. Psychology journals accounted for 64% of the total, management 13.4%, personnel 19%, and Proceedings 3.5%. Implications for research and careers are discussed.A shorter, less-complete version of this paper was presented in summary form at the annual meeting of The Academy of Management in Washington, DC, August 1989 as part of a symposium for the Women in Management Division.  相似文献   
70.
In this paper, we examine the termination of children's mental health services. Analyses were based on the 901 families in the Fort Bragg Evaluation Project who participated at Wave 1 and Wave 2 six months later. The project compared a full continuum of care provided at a demonstration site with traditional care at two comparison sites. The results showed that in most cases families and providers were partners in decisions to terminate treatment. About half of the clients self-terminated or were terminated solely at the discretion of the provider. Providers tended to play a more dominant role in terminating restrictive services; families played a more central role in terminating outpatient care. Regardless of initial psychopathology, children in single-headed households, whose parents were dissatisfied with services, did not expect their child to cooperate with treatment and did not expect treatment to help their child, were more likely to terminate care than others. While the Demonstration site had significantly fewer terminations, the sites did not differ with regard to the reasons for termination, who participated in termination decisions, or the factors that affected the likelihood to terminate care. Of most interest, mental health outcomes among children who had terminated all care did not vary by reasons for termination or by who participated in the termination decision.  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