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   1200篇
  免费   46篇
  2023年   9篇
  2021年   14篇
  2020年   17篇
  2019年   26篇
  2018年   34篇
  2017年   26篇
  2016年   42篇
  2015年   26篇
  2014年   20篇
  2013年   107篇
  2012年   48篇
  2011年   52篇
  2010年   22篇
  2009年   25篇
  2008年   35篇
  2007年   38篇
  2006年   32篇
  2005年   36篇
  2004年   33篇
  2003年   43篇
  2002年   29篇
  2001年   18篇
  2000年   34篇
  1999年   27篇
  1998年   12篇
  1997年   16篇
  1996年   20篇
  1995年   19篇
  1994年   10篇
  1993年   9篇
  1992年   21篇
  1990年   18篇
  1989年   17篇
  1988年   16篇
  1987年   24篇
  1986年   15篇
  1985年   13篇
  1984年   17篇
  1982年   8篇
  1981年   11篇
  1980年   17篇
  1978年   21篇
  1977年   15篇
  1976年   13篇
  1975年   19篇
  1974年   17篇
  1973年   15篇
  1972年   9篇
  1971年   10篇
  1966年   13篇
排序方式: 共有1246条查询结果,搜索用时 15 毫秒
191.
As the older adult population continues to grow, the prevalence of chronic diseases is also increasing, leading to the need for novel ways of managing this large population of patients. One solution is to focus on informal caregivers. These informal caregivers already make a substantial contribution to our nation’s healthcare finances and patient health outcomes. Caregivers also derive benefits from caring for their family member or friend; however, it is not uncommon for these individuals to experience negative health consequences, or what is often called “burden of care.” Those called to care are not without their own burdens, and they must frequently make significant lifestyle adjustments that impact their own health. Therefore, for caregivers to be effective, caring for the caregivers must be a focus of medicine in the twenty-first century.  相似文献   
192.
The defense of offspring, termed maternal aggression, is a highly conserved behavior in mammals, including rodents. This study examined relative levels of maternal aggression in two closely related dwarf hamster species, Phodopus campbelli and P. sungorus, that normally inhabit high latitude, boreal environments. When tested with first litters and with the breeder male remaining with the female (for P. campbelli the male is necessary for successful rearing of offspring), both species exhibited high levels of maternal aggression with average duration of aggressive behavior>80 sec for a 10 min test. For P. sungorus, males are not required to rear offspring. P. sungorus females with either one or multiple litters (singly housed after impregnation) exhibited significantly higher levels of aggression (>300 sec) relative to females co‐housed with the sires. In terms of species differences in attack style, P. campbelli exhibited a boxing or clawing strategy for ~50% of total attack time, but for P. sungorus, this form of attack occurred<5% of the time. For P. sungorus, attacks to the vulnerable belly and flank constituted>90% of all attacks, but these regions were attacked ~50% of the time for P. campbelli. A survey of levels of maternal aggression of rodents in other genera suggests that maternal aggression in Phodopus is at the high end of the spectrum. Results of this study suggest that the presence of the breeder male may actually suppress aggression in P. sungorus. This fact, as well as its high level of aggression and its distant relationship to mice and rats, suggest P. sungorus as a possible model for future studies on the neurobiological basis of maternal aggression. The relationship between the high rates of maternal aggression and life history strategy in Phodopus is discussed. Aggr. Behav. 00:000–000, 2005. © 2005 Wiley‐Liss, Inc.  相似文献   
193.
194.
195.
Building collaborative multidisciplinary mental health teams to boost student achievement has been a growing initiative in American schools since the 1970s. Marriage and Family Therapists (MFTs)joined those teams in 2008, when Connecticut became the first state to certify MFTs for schoolbased practice. This article chronicles the history of that collaboration and reports initial research into MFT school-based participation on those teams.  相似文献   
196.
Although the measurement of working memory capacity is crucial to understanding working memory and its interaction with other cognitive faculties, there are inconsistencies in the literature on how to measure capacity. We address the measurement in the change detection paradigm, popularized by Luck and Vogel (Nature, 390, 279-281, 1997). Two measures for this task-from Pashler (Perception & Psychophysics, 44, 369-378, 1988) and Cowan (The Behavioral and Brain Sciences, 24, 87-114, 2001), respectively-have been used interchangeably, even though they may yield qualitatively different conclusions. We show that the choice between these two measures is not arbitrary. Although they are motivated by the same underlying discrete-slots working memory model, each is applicable only to a specific task; the two are never interchangeable. In the course of deriving these measures, we discuss subtle but consequential flaws in the underlying discrete-slots model. These flaws motivate revision in the modal model and capacity measures.  相似文献   
197.
The role of epigenetic mechanisms in control of gene expression during mammalian development is well established. Associations between specific DNA or histone modifications and numerous neurodevelopmental and neurodegenerative disorders implies significant consequences of epigenetic dysregulation in both the developing and mature brain, the latter of which is the general focus of this review. Accumulating evidence suggests that epigenetic changes are involved in normal cognitive processes in addition to neurological and psychiatric disorders. Recent investigations into the regulation of epigenetic modifications in the adult brain have revealed novel and surprisingly dynamic mechanisms for controlling learning and memory-related behaviors as well as long-term synaptic plasticity. DNA methylation and histone acetylation have also been implicated in the modulation of basal synaptic transmission and the balance between excitation and inhibition in various brain regions. Studies have begun to uncover some of the alterations in gene expression that appear to mediate many of these effects, but an understanding of the precise mechanisms involved is still lacking. Nevertheless, the fundamental importance of epigenetic processes in influencing neuronal activity is becoming increasingly evident.  相似文献   
198.
Studies have demonstrated that maternal stress and perceptions of self-efficacy influence a mother's performance, affecting her ability to interact with her child and to understand and answer his needs. The purpose of this study was to evaluate maternal stress and the perception of self-efficacy in the mothers of infants who are cared for in child-care centers and belong to the poorest segment of the Chilean population. To this end, these aspects were studied in 121 low-income, high-social-risk mothers with children between the ages of 4 and 9 months. The final goal was to generate an explicative model of self-efficacy and maternal stress that considered characteristics of the family and the child. The results revealed that family characteristics - especially household size, per capita incomes and mother age - are more relevant for explaining maternal self-efficacy and stress. The findings and implications for practice are discussed.  相似文献   
199.
At the time of this writing, a widely publicized, waived-consent trial is underway. Sponsored by Northfield Laboratories, Inc. (Evanston, IL) the trial is intended to evaluate the emergency use of PolyHeme?, an oxygen-carrying resuscitative fluid that might prevent deaths from uncontrolled bleeding. The protocol allows patients in hemorrhagic shock to be randomized between PolyHeme? and saline in the field and, still without consent, randomized between PolyHeme? and blood after arrival at an emergency department. The Federal regulations that govern the waiver of consent restrict its applicability to circumstances where proven, satisfactory treatments are unavailable. Blood-the standard treatment for hemorrhagic shock-is not available in ambulances but is available in hospitals. The authors argue that the in-hospital stage of the study fails to meet ethical and regulatory standards.  相似文献   
200.
The present study sought to explore how women's life experiences influenced their beliefs, and how those beliefs in turn influenced feminist self-identification. Additionally, we sought to determine whether feminist self-identification led to increased collective action on behalf of women. Female participants (N?=?282) from two US college campuses and online listservs completed an online survey assessing feminist self-identification, collective action, and life experiences. Conservative, liberal, and radical beliefs were assessed as were evaluations of feminists. A structural equation model was used to explore these relationships; life experiences were found to influence women's beliefs, which in turn influenced feminist self-identification, which influenced collective action. We found that life experiences may serve as a catalyst for both feminist self-identification and collective action.  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