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   32524篇
  免费   1225篇
  国内免费   19篇
  33768篇
  2020年   313篇
  2019年   435篇
  2018年   581篇
  2017年   634篇
  2016年   594篇
  2015年   451篇
  2014年   503篇
  2013年   2560篇
  2012年   869篇
  2011年   995篇
  2010年   650篇
  2009年   646篇
  2008年   903篇
  2007年   840篇
  2006年   798篇
  2005年   669篇
  2004年   622篇
  2003年   669篇
  2002年   609篇
  2001年   1206篇
  2000年   1184篇
  1999年   857篇
  1998年   382篇
  1997年   314篇
  1994年   315篇
  1992年   727篇
  1991年   702篇
  1990年   666篇
  1989年   621篇
  1988年   587篇
  1987年   592篇
  1986年   555篇
  1985年   614篇
  1984年   487篇
  1983年   372篇
  1981年   303篇
  1979年   466篇
  1978年   347篇
  1977年   338篇
  1976年   310篇
  1975年   422篇
  1974年   421篇
  1973年   479篇
  1972年   386篇
  1971年   323篇
  1970年   307篇
  1969年   330篇
  1968年   380篇
  1967年   335篇
  1966年   385篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
The cellular expression of S-100β protein is upregulated in Alzheimer's disease and in Down's syndrome, and this protein has been implicated in memory-related processes in laboratory animals. However, the possibility that the α subunit of S-100 is also involved in memory has not yet been examined. In the present study, day-old black Australorp white Leghorn cockerel chicks (Gallus domesticus) received injections of monoclonal antisera to S-100α (1:50) or S-100β (1:500) into each hemisphere immediately after training on a one-trial passive avoidance task. The chicks displayed significantly lower retention levels than control birds that had been injected with antisera to carbonic anhydrase, or with saline (p< .01). S-100α antisera had an amnestic effect when injected between 0 and 20 min after training, with memory deficits occurring from 30 min postlearning, at the point of transition between the A and the B phases of the Gibbs-Ng intermediate memory stage. By contrast, the S-100β antisera needed to be injected either 5 min before or immediately after training and produced amnesia 10 min earlier, at the start of the A phase of the intermediate memory stage. We conclude that the two subunits of the S-100 protein are required at different points in the sequence of events leading to the consolidation of passive avoidance memory.  相似文献   
982.
983.
984.
Homographs and homophones have interesting linguistic properties that make them useful in many experiments involving language. To assist researchers in the elicitation of homophones, this paper presents a set of 93 line-drawn pictures of objects with homophonic names and a set of 108 questions with homophonic answers. Statistics are also included for each picture and question: Picture statistics include name-agreement percentages, dominance, and frequency statistics of depicted referents, and picture-naming latencies both with and without study of the picture names. For questions, statistics include answer-agreement percentages, difficulty ratings, dominance, frequency statistics, and naming latencies for 60 of the most consistently answered questions.  相似文献   
985.
The musical instrument digital interface (MIDI) offers a way for perception and behavior researchers to implement high-quality experiments using inexpensive, commercially available hardware and software. We describe the MIDI and illustrate its applicability to research using a replication of the oscillator signature finding reported recently by Collyer, Broadbent, and Church (1992, 1994).  相似文献   
986.
The integration of binocular stereopsis and kinetic depth was measured for two distinct aspects of 3-Dstructure: (1)shape index, which is a measure of scale-independent structure, and (2)curvedness, which is a measure of scale-dependent structure. We found that motion contributes significantly more to judged shape index than it does to judged curvedness, and stereo contributes significantly more to judged curvedness than it does to judged shape index. This suggests that the differences in the relative contribution of motion and stereo reported here occurred because these two sources do not equally specify the scale-dependent and scale-independent aspects of surface structure. Furthermore, these results seem to be inconsistent with integration models in which the different visual cues all initially contribute to the same single representation of 3-Dstructure.  相似文献   
987.
Several cases encountered in psychiatric practice are described in which herpetic involvement of the trigeminal nerve appeared to be crucial to the pathophysiology of the patients’s illness. A brief history of herpes is discussed in terms of the anatomy and physiology of the trigeminal nerve. Particular attention is given to the effects of intraneuronal herpes on gasserian ganglion and spinal nuclei discharge threshoolds, as well as viral pathways directly impacting the substantia nigra. Evidence characterizing Parkinson’s disease as one of several important manifestations of CNS herpes is covered. This article will be presented, by invitation, at the Neuroscience Seminar, Department of Medicine, University of Otago, Dunedin, New Zealand, on 19 August 1997.  相似文献   
988.
A total of 229 late adolescents (a large majority 15 to 19 years of age) completed a questionnaire that assesses a broad range of videogame-relevant experiences, preferences, and attitudes. Videogame playing was found to be a more popular, and a more highly regarded, activity among males than females. Gender differences were also found in participants' ratings of their motivations for playing videogames, their evaluations of particular characteristics of videogames, and their selection of their “most favorite” videogame. The differences between frequent and infrequent videogame players appeared to be limited to differences in the extent to which videogame playing is pursued and evaluated as a positive leisure activity, rather than reflecting broad differences in interest or personality. Some relations were found between participants' self-reported personality characteristics (i.e., self-esteem, empathy, conscientiousness, and introversion) and their attitudes toward videogames.  相似文献   
989.
990.
ABSTRACT College students who had yet to marry and begin a family were asked about their desire to have children and their beliefs and expectations about themselves as parents (Study 1) and the characteristics of their prospective children (Study 2). Persons with more avoidant and anxious-ambivalent models of close adult relationships harbored more negative models of parent-hood and parent-child relationships. These findings indicate that working models of parenting and parent-child relationships form well before marriage and the birth of children and that these models are systematically associated with attachment styles in adult relationships. The findings also suggest ways in which insecure attachments between child and parent may be influenced by the caregiver's models of parenting and parent-child relationships.  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