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   35697篇
  免费   1437篇
  国内免费   10篇
  37144篇
  2019年   468篇
  2018年   607篇
  2017年   635篇
  2016年   647篇
  2015年   457篇
  2014年   581篇
  2013年   2703篇
  2012年   1053篇
  2011年   1136篇
  2010年   679篇
  2009年   671篇
  2008年   1003篇
  2007年   971篇
  2006年   920篇
  2005年   836篇
  2004年   804篇
  2003年   752篇
  2002年   792篇
  2001年   1066篇
  2000年   970篇
  1999年   762篇
  1998年   412篇
  1997年   348篇
  1996年   344篇
  1992年   579篇
  1991年   589篇
  1990年   565篇
  1989年   564篇
  1988年   562篇
  1987年   534篇
  1986年   553篇
  1985年   605篇
  1984年   502篇
  1983年   467篇
  1982年   400篇
  1981年   388篇
  1979年   561篇
  1978年   414篇
  1977年   367篇
  1976年   402篇
  1975年   479篇
  1974年   532篇
  1973年   550篇
  1972年   432篇
  1971年   402篇
  1970年   397篇
  1969年   422篇
  1968年   507篇
  1967年   447篇
  1966年   448篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
Relationships of serum and saliva to personality were examined among 401 college students in four laboratory studies and 5,236 military veterans in one archival study. Among the students, there were few relationships between testosterone and traditional personality measures. Among the veterans, MMPI scores and DSM-III diagnoses showed testosterone related to drug and alcohol abuse, antisocial and generally intemperate behavior, and effective disorders. Consistent with social control theory, correlations were higher among veterans who were lower in socioeconomic status. It appears likely that testosterone has innate effects that are socially undesirable but can be attenuated by bonds between the individual and society. Effect sizes were small, suggesting that testosterone will have noticeable effects only in large populations or individuals who differ markedly from the population mean. Further research should focus upon antisocial correlates of testosterone and conditions that produce marked changes in testosterone levels.  相似文献   
983.
984.
Marked differences in detectability as a function of spatial location, a "detectability gradient," are observed when subjects are required to detect a briefly exposed target pattern of uncertain location in the presence of a number of nontarget patterns. Target detectability also is inversely related to the number of nontarget patterns which are present in this search paradigm. These previous findings provide strong evidence for a serial process in which increasing probability of error occurs during a scan of a rapidly degrading neural representation of the visual image following a brief exposure to the stimuli. It is not yet established whether this scan is attentional or perceptual in nature. The present experiments test the hypothesis of an attentional scan by presenting the target and nontarget patterns in spatially segregated groups. If the scan is attentional, then target detectability under these circumstances would be expected to exhibit the characteristic phenomenon of "group processing"--a close clustering of detection performance for targets located within a group and large differences in detectability across groups. As no evidence for group processing was observed, the results fail to support the view that the scan is attentional in nature but are fully consistent with a nonattentional scan.  相似文献   
985.
Previous experiments in this laboratory employing a search paradigm have found highly significant differences in the detectability of a briefly exposed target pattern as a function of the spatial location of the target when it is presented simultaneously with a number of discriminably different nontarget patterns. These detectability differences, at loci equidistant from the fovea, could not be accounted for by any known variation in retinal spatial resolution or by differential lateral masking effects of the target by nearby nontarget patterns. These observations led to the hypothesis that the target in these experiments was detected by a serial mechanism which "scanned" a persisting but rapidly degrading neural representation of the visual scene with increasing detection failures the later in time the scan processed the location occupied by the target. If this hypothesis is correct, then target detectability should vary inversely with the number of stimuli which must be examined. The present experiment confirmed this expectation. A mathematical model of such a serial scanning process also predicts other, less obvious, effects on target detectability which were observed when the number of nontarget patterns was changed.  相似文献   
986.
Summary The role of intention in guiding the behavior of goal-directed systems is a problem that continues to challenge behavioral science. While it is generally agreed that intentional systems must be consistent with the laws of physics, there are many obvious differences between inanimate, physical systems and sentient, intentional systems. This suggests that there must be constraints over and above those of physics that govern goal-directed behavior. In this paper it is suggested that generic properties of self-organizing mechanisms may play a central role in the origin and evolution of intentional constraints. The properties of self-organizing systems are first introduced in the context of simple physical systems and then extended to a complex (biological) system. Whereas behavior of an inanimate physical system is lawfully determined by force fields, behavior of an animate biological system is lawfully specified by information fields. Biological systems are distinguished from simple physical systems in terms of their ubiquitous use of information fields as special (biological and psychological, social, etc.) boundary conditions on classical laws. Unlike classical constraints (boundary conditions), informational constraints can vary with time and state of the system. Because of the nonstationarity of the boundary conditions, the dynamic of the system can follow a complex trajectory that is organized by a set of spatially and temporally distributed equilibrium points or regions. It is suggested that this equilibrium set and the laws that govern its transformation define a minimal requirement for an intentional system. One of the benefits of such an approach is that it suggests a realist account for the origin of semantic predicates, thereby providing a basis for the development of a theory of symbolic dynamics. Therefore, the principles of self-organization provide a comprehensive basis for investigating intentional systems by suggesting how it is that intentions arise, and by providing a lawful basis for intentional behavior that reveals how organisms become and remain lawfully informed in the pursuit of their goals.  相似文献   
987.
Are women in a female-dominated profession more successfully able to combine work and family obligations than women in a male-dominated profession? To explore this question, a comparison was made between the family status and careers of 747 women librarians (a female-dominated profession) and those of 449 women MBAs (a male-dominated profession). It was expected that the librarians would marry earlier and have more children. This general prediction was not supported. Over half of both groups of women were married, and after controlling for age, there were no differences in number of children. However, many women without children in both groups reported that they would like to be mothers. This disparity between wanting children and not having them was more common for women MBAs than women MLSs. MBAs and librarians were about equally likely to have had job interruptions, but librarians were more likely to have worked part-time. Reasons for an interruption to full-time work were as likely to be for problems finding (full-time) work as for family responsibilities. Librarians' salaries were much lower, but job interruptions and part-time work had a more negative effect on the salaries of women in business. In sum, the data suggest that many of the women surveyed have not combined motherhood with a professional career and that it is probably somewhat more difficult to combine a family with a career in business than with a career in library science.  相似文献   
988.
This study tested the applicability of Tajfel and Turner's (1986) Social Identity Theory (SIT) to cooperative behavior in a mixed-gender setting. SIT suggests that as a “socially subordinate” group in a male-dominated society, women, when their gender is in the numerical minority, will engage in social competition in an attempt to enhance social identity. However, gender-based socialization may encourage men toward competition and women toward cooperation, regardless of group gender composition. In this study, male and female subjects were assigned to a six-person mixed-gender group in which their gender was either in the numerical minority or majority, and performed an interactive task under either cooperative or competitive feedback. An interaction of sex and feedback showed males in the cooperative feedback condition responded more competitively than did males in the competitive feedback condition, while females were equally cooperative in both feedback conditions. Feedback also interacted with the numerical ingroup/outgroup gender balance. While competitive feedback elicited little variation in subjects' responses across the ingroup/outgroup balance variable, the cooperative condition elicited greater competition from subjects in the numerical minority and greater cooperation from those in the numerical majority. Results were interpreted as partial support for SIT, while stressing the need for further investigation into gender as a unique influence on intergroup behavior.  相似文献   
989.
990.
The relationship between program performance and outcome for patients in maximum security token economy programs has not been previously studied. We examined variables related to success in a token economy program and to postrelease failure for 92 men in a maximum security psychiatric hospital. Point earnings later in the program were best predicted by earlier point earnings. Variables that best predicted postrelease failure, defined in various ways, were similar to those found in other studies; youthfulness, having spent more time in institutions, a diagnosis of personality disorder or retardation rather than psychosis, not having been found not guilty by reason of insanity or unfit to stand trial, and having been referred from another psychiatric hospital. That program variables were generally unrelated to later outcome suggests that treatment programs for patients in maximum security settings must emphasize skills that are relevant to postrelease success.  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