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   178477篇
  免费   7830篇
  国内免费   163篇
  186470篇
  2021年   1529篇
  2020年   2803篇
  2019年   3468篇
  2018年   3653篇
  2017年   4081篇
  2016年   4724篇
  2015年   3947篇
  2014年   4831篇
  2013年   23660篇
  2012年   4914篇
  2011年   3988篇
  2010年   4062篇
  2009年   4864篇
  2008年   4198篇
  2007年   3816篇
  2006年   4315篇
  2005年   4249篇
  2004年   3728篇
  2003年   3395篇
  2002年   3184篇
  2001年   3399篇
  2000年   3236篇
  1999年   3255篇
  1998年   2836篇
  1997年   2693篇
  1996年   2592篇
  1995年   2454篇
  1994年   2398篇
  1993年   2357篇
  1992年   2706篇
  1991年   2498篇
  1990年   2393篇
  1989年   2271篇
  1988年   2271篇
  1987年   2280篇
  1986年   2242篇
  1985年   2432篇
  1984年   2553篇
  1983年   2359篇
  1982年   2395篇
  1981年   2360篇
  1980年   2216篇
  1979年   2289篇
  1978年   2226篇
  1977年   2180篇
  1976年   1995篇
  1975年   2050篇
  1974年   2106篇
  1973年   2000篇
  1972年   1539篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
901.
902.
Much of the methodology in stress research focuses on stress manifestation and organismic reactions to life’s crises. In contrast, the present study sought to identify the major sources of stress and the nature of those sources. The results revealed a consistent pattern in high and low stressors throughout the 3-year period of the study, and differences only of intensity between males and females, not type of stress. Except for individuals’ temporal variations in critical events, the highest stressors for the groups were external, primarily financial and time management. Internal sources, such as personal relationships and self-absorption, were typically the lowest concerns. Everyday problems arising from current life styles seem to be significant sources of stress.  相似文献   
903.
Postinstitutional arrests and state hospitalizations of 191 patients placed on conditional release (CONREP group) were compared to those of 44 patients released from the same California state hospital with no aftercare due to expiration of commitment terms (MAXOUT group). The two groups were not randomly determined but were comparable in demographic characteristics and rates of preprogram arrest. The CONREP group had a significantly lower community-period arrest rate than did the MAXOUT group (p <.001). Survival rate analyses, using time until arrest and time until revocation as dependent variables, suggested that revocations during the first 240 days of community re-entry reduced the potential arrest rate within the CONREP group. Results were discussed in terms of the “criminalization hypothesis” as well as the crime-preventive possibilities of the conditional release mechanism.  相似文献   
904.
Since the Supreme Court's decision in Faretta v. California (1975), courts have generally permitted defendants to represent themselves, as long as they are competent to do so. The problem lies in the definition of competency to waive counsel, which has been vaguely defined by the courts. Little is known about the frequency of, or reasons for, attempts to waive counsel, about the process of forensic evaluation of such competency, and about the success of such attempts. The authors briefly review the case law on competency to waive representation, report on a longitudinal prospective study of these issues in a population of defendants referred to an inpatient forensic facility for evaluation of all types of competency related to their criminal prosecutions, and discuss the significance of the issue for forensic clinicians. A key question for courts, lawyers, and clinicians is whether a competency evaluation can be invoked to overcome a defendant's constitutional rights to self-representation and bail.  相似文献   
905.
I examined preweanling rats' (Rattus norvegicus) expression of ultrasounds and secretion of ACTH when exposed to unfamiliar adult male rats or to their mothers. Pups at 7 days of age produced similar levels of ultrasonic vocalization near both unfamiliar males and mothers. However, these pups could discriminate familiar from unfamiliar adults because ACTH was significantly higher in pups near adult males than in those near mothers. At 14 days of age, pups avoided adult males but not their mothers; therefore, adult males represented a significant threat. Importantly, 14-day-old rats significantly reduced ultrasound production only when near adult males. Pups at 21 days of age no longer emitted ultrasounds when socially isolated or when near conspecific adults. In addition, 14- and 21-day-old rats produced similar elevated ACTH levels across stimulus conditions. Results show significant changes in preweanling rats' responses to conspecific adults.  相似文献   
906.
Francis O. Schmitt 《Zygon》1992,27(4):437-454
Abstract. Many centers are now active in the study of the interaction between science on the one hand and theology on the other. Suggestions are made as to how such study might be furthered. The central proposal in this paper is based on the author's experience in founding and, over many years, operating the Neurosciences Research Program (NRP). The "faculty" of this group were highly competent in many fields of science and were able to deal with many of the major issues. It is here further suggested that if an NRP-like organization were established, capable of productively interacting with both science and theology, it might well generate new concepts and possibly a new paradigm in this context.  相似文献   
907.
908.
Roger W. Sperry 《Zygon》1992,27(3):245-259
Abstract. My account of the recent turnabout in the treatment of mental states in science and its basis in a modified concept of causal determinism and my claim that this opens the way for beliefs and values consistent with science are here reaffirmed in response to perceived weaknesses and "inherent incompleteness." Contested issues are reviewed to better clarify the main thesis. An inherent weakness in respect to deep spiritual needs is recognized and tentative remedial measures explored.  相似文献   
909.
Two experiments are reported which investigated how subject gender and time-of-day influenced the estimation of duration and the perception of task-related mental workload. In the first experiment, 24 subjects performed a filled time-estimation task in a constant blacked-out, noise-reduced environment at 0800h, 1200h, 1600h, and 2000h, respectively. In the second experiment, 12 different subjects performed an unfilled time estimation task in similar conditions at 0900h, 1400h, and 1900h. At the termination of all experimental sessions, participants completed the NASA Task Load Index workload assessment questionnaire as a measure of perceived mental workload. Results indicated that physiological response, reflected in body temperature change, followed an expected pattern of sequential increase with time-of-day. However, estimates of duration and the perception of mental workload showed no significant effects for time-of-day. In each of the experiments there were significant differences in time estimation and mental workload response contingent on the gender of the participant. These results are interpreted in light of the previous positive findings for circadian fluctuation in performance efficiency and the equivocal findings of a gender difference in time estimation. A unifying account of these collective results is given based on gender by time-of-day interactional effects. An earlier version of this paper was presented at the 32nd Annual Meeting of the Human Factors Society, Anaheim, CA, October, 1988.  相似文献   
910.
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