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   179510篇
  免费   7994篇
  国内免费   156篇
  187660篇
  2020年   2794篇
  2019年   3449篇
  2018年   3527篇
  2017年   3982篇
  2016年   4614篇
  2015年   3933篇
  2014年   4808篇
  2013年   23466篇
  2012年   4660篇
  2011年   3734篇
  2010年   3894篇
  2009年   4784篇
  2008年   3961篇
  2007年   3489篇
  2006年   4076篇
  2005年   4083篇
  2004年   3562篇
  2003年   3183篇
  2002年   3006篇
  2001年   3551篇
  2000年   3397篇
  1999年   3310篇
  1998年   2849篇
  1997年   2679篇
  1996年   2602篇
  1995年   2432篇
  1994年   2402篇
  1993年   2363篇
  1992年   2810篇
  1991年   2648篇
  1990年   2524篇
  1989年   2389篇
  1988年   2352篇
  1987年   2384篇
  1986年   2372篇
  1985年   2634篇
  1984年   2641篇
  1983年   2420篇
  1982年   2403篇
  1981年   2380篇
  1980年   2200篇
  1979年   2369篇
  1978年   2234篇
  1977年   2196篇
  1976年   2016篇
  1975年   2166篇
  1974年   2247篇
  1973年   2156篇
  1972年   1734篇
  1971年   1659篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
It is known that speed and accuracy in recognizing words are constrained by the frequency of occurrence of these words ("frequency effect"). This study examines the relationship between educational level and the word frequency effect. We postulated that individual exposure to words that are rated lower in frequency tables should be greater among subjects with higher education and therefore hypothesized that the magnitude of the frequency effect should not be as marked within such a population as among subjects with a lesser educational level. A total of 40 neurologically healthy adults, half with an average of 18 years of formal education and the other half with an average of 11 years, participated in a lexical decision experiment. Results confirmed our hypothesis; that is, significant frequency effects on reaction times were obtained in both groups but this effect was of greater magnitude for the less educated as opposed to the more educated subgroup. The significance of this finding is discussed by reference to current models of word recognition.  相似文献   
912.
This study was undertaken to confirm previous findings that Long-Evans rats exhibit age-related changes in the diurnal/nocturnal distribution of water intake and to examine the circadian pattern of these age-related changes. Twenty-one aged and 10 young pathogen-free rats were continuously monitored for water consumption over 12:12 h light/dark cycles. ANOVA, profile analysis, and cosinor analysis each demonstrated that aged rats differed from young rats. The age-related changes in circadian pattern can be described as a blunted rhythm (decreased amplitude) and an altered timing of peak activity (advanced acrophase). These differences, however, were only apparent in a subset of aged rats with the remaining aged rats exhibiting a circadian pattern indistinguishable from that of the young group.  相似文献   
913.
Norway rat fetuses (Rattus norvegicus) exhibit a stereotypic behavioral response when the umbilical cord is experimentally compressed with a vascular clamp. In this study, the development of the fetal behavioral response to cord compression was compared in altricial and precocial rodents, which differ markedly in neural and motor maturity at the time of birth. Both altricial and precocial species showed some form of behavioral response to umbilical cord compression. Fetuses of two altricial species, Norway rats and Mongolian gerbils (Meriones unguiculatus), expressed hyperactivity in response to cord compression throughout the last third of gestation. In contrast, precocial cotton rats (Sigmodon hispidus) and spiny mice (Acomys cahirinus) did not respond to cord compression until relatively late in gestation. Thus, altricial and precocial species do not express the cord compression response during comparable periods of neural development: precocial species are much more mature at the earliest expression of this behavior than altricial species. These findings are consistent with the interpretation that the cord compression response is a behavioral adaptation that can promote survival of the fetus in utero.  相似文献   
914.
Reports that the dihydropyridine Ca2+ channel antagonists may facilitate memory led to the present study of the behavioral effects of nifedipine. Ninety-two 4-day-old male chicks received 0, 100 nM, 100 microM, or 10 mM nifedipine. Drugs were administered in volumes of 2 microliters into the fourth cerebral ventricle 5 min before training on a visual discrimination task. Nifedipine did not produce any detectable changes in behavior during acquisition trials. Retention, however, was impaired 24 h after training in the 100 nM and 100 microM nifedipine-treated chicks, which made significantly more errors than controls. Nifedipine did not affect the amount of time required to complete the task. No effects on body weight gain were detected, suggesting that the memory impairment was not due to a change in feeding behavior. These data are discussed in terms of the role of calcium-dependent processes in memory.  相似文献   
915.
916.
A multivariate hierarchical model of specific cognitive abilities was fitted to data from 7-year-old adopted and nonadopted sibling pairs in the Colorado Adoption Project in order to assess differential genetic influence on specific mental abilities. Model fitting results and Schmid-Leiman (Schmid & Leiman, 1957) transformations reveal significant heritable variation for verbal, spatial, and memory factors independent of general cognitive ability for the eight ability tests examined. In contrast, environmental influences are primarily measure-specific. The results suggest genetic effects in middle childhood that differentially influence mental ability scores.  相似文献   
917.
A feminist psychospiritual model of therapy that can be used in working with clients who value the spiritual dimension in their lives is offered. The history, philosophy, and work of Women for a New World, a multidisciplinary team of women representing the areas of psychology, religious education, and the arts is presented. Using examples drawn from the developmental history of our retreat-workshop paradigm and from some of our programs, including a weekend retreat for women and a day of reflection for persons affected by AIDS (including family and friends of those with AIDS), the metaphor of therapy as soul healing is developed.  相似文献   
918.
Surprisingly little has been written in the counseling journals on the topic of lying: that is, why some clients consciously choose to be either dishonest with their counselors or deliberately hold back (i.e., keep secrets) important information from their counselors. This article discusses the dynamics of lying and offers suggestions to counselors on how to work with clients who lie.  相似文献   
919.
920.
Wistar rats (n = 95) were trained in a pole-jumping apparatus (10 trials/session/day) to investigate the involvement of centrally and peripherally released endogenous AVP in their acquisition rate and to examine the feasibility of the microdialysis technique for the administration of peptides during a behavioral test. After session 1, a microdialysis probe was implanted into the septum; during sessions 2 and 3 the probe was perfused with artificial cerebrospinal fluid (aCSF) alone or containing either AVP (delivered amount via the probe: 0.2 ng) or the V1 (d(CH2)5Tyr(Me)AVP, 5.0 ng) or the V2/V1 (d(CH2)5-D-Tyr(Et)VAVP, 5.0 ng) antagonist. Administration of AVP via microdialysis into the septum failed to alter the acquisition rate of pole jumping. Also, ip application of both hypertonic saline and the AVP V1 antagonist (10 micrograms) in another experiment failed to show a significant effect upon behavior. Septal administration of the V1 or the V2/V1 antagonist via microdialysis, however, produced a significantly impaired performance. The results indicate that AVP release within the septum is involved in the acquisition of pole-jumping behavior probably mediated by the V1 receptor subtype. An additional involvement of the V2 receptor subtype, however, cannot be entirely excluded. The microdialysis technique proved to be a potent tool to administer substances concomitantly with behavioral tests.  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