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   4081篇
  免费   1539篇
  国内免费   305篇
  2024年   5篇
  2023年   28篇
  2022年   50篇
  2021年   136篇
  2020年   146篇
  2019年   427篇
  2018年   318篇
  2017年   427篇
  2016年   414篇
  2015年   391篇
  2014年   341篇
  2013年   582篇
  2012年   336篇
  2011年   283篇
  2010年   301篇
  2009年   278篇
  2008年   255篇
  2007年   191篇
  2006年   174篇
  2005年   166篇
  2004年   129篇
  2003年   121篇
  2002年   117篇
  2001年   93篇
  2000年   80篇
  1999年   47篇
  1998年   13篇
  1997年   6篇
  1996年   7篇
  1995年   6篇
  1994年   8篇
  1993年   3篇
  1992年   9篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   1篇
  1987年   3篇
  1986年   5篇
  1985年   6篇
  1984年   1篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1976年   1篇
排序方式: 共有5925条查询结果,搜索用时 31 毫秒
81.
Humans conduct visual search more efficiently when the same display is presented for a second time, showing learning of repeated spatial contexts. In this study, we investigate spatial context learning in two tasks: visual search and change detection. In both tasks, we ask whether subjects learn to associate the target with the entire spatial layout of a repeated display (configural learning) or with individual distractor locations (nonconfigural learning). We show that nonconfigural learning results from visual search tasks, but not from change detection tasks. Furthermore, a spatial layout acquired in visual search tasks does not enhance change detection on the same display, whereas a spatial layout acquired in change detection tasks moderately enhances visual search. We suggest that although spatial context learning occurs in multiple tasks, the content of learning is, in part, task specific.  相似文献   
82.
In this paper, we discuss the weakness of current action languages for sensing actions with respect to modeling domains with multi-valued fluents. To address this problem, we propose a language with sensing actions and multi-valued fluents, called AMK, provide a transition function based semantics for the language, and demonstrate its use through several examples from the literature. We then define the entailment relationship between action theories and queries in AMK, denoted by ⊧AMK, and discuss some properties about AMK.  相似文献   
83.
Fear-related processing in the amygdala has been well documented, but its role in signaling other emotions remains controversial. The authors recovered signal loss in the amygdala at high-field strength using an inward spiral pulse sequence and probed its response to pictures varying in their degree of portrayed sadness. These pictures were presented as intermittent task-irrelevant distractors during a concurrent visual oddball task. Relative to neutral distractors, sad distractors elicited greater activation along ventral brain regions, including the amygdala, fusiform gyrus, and inferior frontal gyrus. In contrast, oddball targets engaged dorsal sectors of frontal, parietal, and cingulate cortices. The amygdala's role in emotional evaluation thus extends to images of grief and despair as well as to those depicting violence and threat.  相似文献   
84.
助推爱心:利用默认选项促进捐赠行为   总被引:10,自引:1,他引:9  
宋官东 《心理科学》2005,28(5):1174-1179
本研究采用实验室和现场实验的方法检验了默认选项的助推策略是否能够促进慈善捐赠行为。结果发现:(1)相较于把被试费的“保留选项”设置为默认,把“捐献选项”设置为默认时,被试捐献的概率和金额更高;(2)在多个捐款选项情景中,默认选项的设置总体上提高了默认选项被选择的概率;将最大金额选项设置为默认选项有助于提高被试平均捐赠额。这些发现表明,应用默认选项的助推策略能够有效促进人们的捐赠行为。本研究结果对减少募捐成本、提高募捐效率有所启示。  相似文献   
85.
Omega (n)-3 and n-6 fatty acids are important membrane components of neurons and immune cells, and related to psychiatric and inflammatory diseases. Increased ratio of n-6/n-3 in the blood has been reported in depressed patients and in students following stress exposure. The n-3 fatty acid, eicosapentaenoic acid (ethyl-EPA) suppresses inflammation and has antidepressant properties. Interleukin (IL)-1beta can stimulate corticosterone secretion, induce anxiety and stress-like behavior and inflammatory responses. This study was to evaluate the effect of diets enriched with coconut oil, ethyl-EPA and soybean oil on central IL-1beta induced stress and anxiety-like behavior, induced changes in the concentration of prostaglandin (PG) E2 and corticosterone and the release of IL-10. Groups of rats were fed with either 5% coconut oil (as control diet), 0.2% EPA with 4.8% coconut oil or 1% EPA with 4% coconut oil and 5% soybean oil for 7 weeks. The central administration of IL-1beta induced sickness, stress and anxiety-like behavior as indicated by a reduction in body weight, decreased time spent, and the number of entries, into the open arms of the elevated plus maze and decreased exploration and entry into the central zone of the "open field" apparatus. IL-1beta also increased PGE2 and corticosterone concentrations and decreased the release of IL-10 from leucocytes. Food enriched with ethyl-EPA but not soybean oil, significantly attenuated most of these changes. These results demonstrate that ethyl-EPA has anti-inflammatory, anti-stress and anti-anxiety effects in rats.  相似文献   
86.
Synapses formed by the olfactory nerve (ON) provide the source of excitatory synaptic input onto mitral cells (MC) in the olfactory bulb. These synapses, which relay odor-specific inputs, are confined to the distally tufted single primary dendrites of MCs, the first stage of central olfactory processing. beta-adrenergic modulation of electrical and chemical signaling at these synapses may be involved in early odor preference learning. To investigate this possibility, we combined electrophysiological recordings with calcium imaging in olfactory bulb slices prepared from neonatal rats and mice. Activation of ON-MC synapses induced postsynaptic potentials, which were associated with large postsynaptic calcium transients. Neither electrical nor calcium responses were affected by beta-adrenergic agonists or antagonist. Immunocytochemical analysis of MCs and their tufted dendrites revealed clear immunoreactivity with antibodies against alpha1A (Cav2.1, P/Q-type) and alpha1B (Cav2.2, N-type), but not against alpha1C (Cav1.2, L-type) or alpha1D (Cav1.3, L-type) calcium channel subunits. Moreover, nimodipine, a blocker of L-type calcium channels, had no effect on either electrical or calcium signaling at ON-MC synapses. In contrast to previous evidence, we concluded that in neonatal rats and mice (P5-P8), mitral cells do not express significant amounts of L-type calcium channels, the calcium channel type that is often targeted by beta-adrenergic modulation. The absence of beta-adrenergic modulation on either electrical or calcium signaling at ON-MC synapses of neonatal rats and mice excludes the involvement of this mechanism in early odor preference learning.  相似文献   
87.
Twenty-five newborn infants were tested for auditory-oral matching behavior when presented with the consonant sound /m/ and the vowel sound /a/ - a precursor behavior to vocal imitation. Auditory-oral matching behavior by the infant was operationally defined as showing the mouth movement appropriate for producing the model sound just heard (mouth opening for /a/ and mouth clutching for /m/), even when the infant produced no sound herself. With this new dependent measure, the current study is the first to show matching behavior to consonant sounds in newborns: infants showed significantly more instances of mouth opening after /a/ models than after /m/ models, and more instances of mouth clutching after /m/ models than after /a/ models. The results are discussed in the context of theories of active intermodal mapping and innate releasing mechanisms.  相似文献   
88.
Witte‐Townsend and DiGiulio explore some of the dimensions of knowing that children, teachers and parents may engage together during story‐time. They reflect on some of their own long‐term relationships with children and children's books, especially Phoebe Gilman's Gilman P 1992 Something from nothing (New York, NY, Scholastic Inc)  [Google Scholar] Something from nothing (published in 1992) and Simms Taback's Taback S 1999 Joseph had a little overcoat (New York, NY, Viking‐Penguin)  [Google Scholar] Joseph had a little overcoat, published in 1999. The authors probe issues such as why children ask to hear a favourite story over and over and why they suddenly abandon all interest and move on to a new book. They explore the meaning of the silences that sometimes arise during story‐time, pooling around the young listeners as the last words of the book are read. Witte‐Townsend and DiGiulio remind us of the value of literature in the lives of children and they affirm that the reading and re‐reading of favourite stories enables the understanding of complex human issues and contributes significantly to social, emotional and spiritual growth.  相似文献   
89.
Quality of life of first-degree relatives living in the same household with patients having schizophrenia has not been sufficiently explored. 30 patients with schizophrenia (16 women, 14 men), diagnosed using DSM-IV criteria, 31 of their relatives (15 women, 16 men), and 34 control subjects (21 women, 13 men) were included in the study. The mean age of the patients, their relatives, and the control subects were 39.8 +/- 10.9, 58.1 +/- 12.5 and 37.3 +/- 17.0, respectively. The World Health Oranization Quality of Life-Brief Form was administered to all subjects. Quality of life was worse for the patient group than for their relatives and control subjects, but relatives of the patients and control subjects were not significantly different on Quality of life. Quality of life was negatively correlated with the severity of psychopathology and extrapyramidal side effects induced by antipsychotic drugs in the patients.  相似文献   
90.
Rules of thumb for power in multiple regression research abound. Most such rules dictate the necessary sample size, but they are based only upon the number of predictor variables, usually ignoring other critical factors necessary to compute power accurately. Other guides to power in multiple regression typically use approximate rather than precise equations for the underlying distribution; entail complex preparatory computations; require interpolation with tabular presentation formats; run only under software such as Mathmatica or SAS that may not be immediately available to the user; or are sold to the user as parts of power computation packages. In contrast, the program we offer herein is immediately downloadable at no charge, runs under Windows, is interactive, self-explanatory, flexible to fit the user’s own regression problems, and is as accurate as single precision computation ordinarily permits.  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