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   2979篇
  免费   539篇
  国内免费   245篇
  2024年   7篇
  2023年   55篇
  2022年   66篇
  2021年   86篇
  2020年   179篇
  2019年   194篇
  2018年   186篇
  2017年   211篇
  2016年   209篇
  2015年   151篇
  2014年   155篇
  2013年   703篇
  2012年   104篇
  2011年   146篇
  2010年   85篇
  2009年   106篇
  2008年   114篇
  2007年   121篇
  2006年   103篇
  2005年   84篇
  2004年   76篇
  2003年   60篇
  2002年   52篇
  2001年   41篇
  2000年   40篇
  1999年   34篇
  1998年   21篇
  1997年   29篇
  1996年   20篇
  1995年   24篇
  1994年   18篇
  1993年   23篇
  1992年   16篇
  1991年   13篇
  1990年   9篇
  1989年   16篇
  1988年   10篇
  1987年   11篇
  1986年   14篇
  1985年   16篇
  1984年   13篇
  1983年   7篇
  1982年   10篇
  1981年   14篇
  1980年   16篇
  1979年   18篇
  1978年   17篇
  1977年   30篇
  1976年   18篇
  1975年   12篇
排序方式: 共有3763条查询结果,搜索用时 31 毫秒
81.
In this paper,we propose a random-access model for describing several wireless communication technologies. These networks have found application in the construction of wireless sensor networks, and the proposed model can be used for flows with different properties, considering the corresponding distribution functions. The model considers the technical features of the LoRa technology and subscriber traffic. We also address the management of random multiple wireless access in a Software-Defined Networking (SDN) like control architectures, and proposing a model for flows with different properties, considering the corresponding distribution functions. We develop a method for optimizing the parameters of an access network by the probability of data delivery. Then we describe the probability of bit error, frame loss, collision, and the choice of network parameters considering the heterogeneity of conditions for different users. Numerical results show the efficiency of our proposed scheme by maintaining the required network parameters in case of its function conditions changing.  相似文献   
82.
83.
如何揭示群体规范和公平价值在个体心理发展中的作用机理, 提升儿童-青少年在群际互动当中的公平感知与规范执行, 是教育心理领域的关键问题。公平规范执行中内群体偏爱现象是近年来的研究热点之一, 然而先前研究存在以下不足:1)大多采用问卷法, 易受社会赞许性的影响, 存在言行不一致的情况; 2)大多采用情景实验, 聚焦社会互动的最终行为输出端, 无法实时有效地把握社会决策的动态进程; 3)脑成像研究仍以fMRI技术为主, 侧重于评估认知加工潜在的脑区激活模式及各脑区间的功能连接, 缺乏对群际公平规范执行中大脑激活动态模式的精确把握。针对这些不足, 本项目从资产分配情景出发, 以儿童和青少年为研究对象, 联合运用认知、行为、眼动和电生理等多层次测评手段, 对公平规范执行中内群体偏爱的发生过程进行认知解析, 探讨认知控制和心智化在其间的关键作用机制及其心理发展轨迹。研究结果将服务于中小学管理中的德育教育, 引导与培养学生的公正感与行为。  相似文献   
84.
自然体验是指个体通过各种感官感知自然或与源于自然界的刺激互动。学者通常使用问卷测量法、自然指标法或实验操纵法来量化操纵人们的自然体验,发现接触自然可以在心理、生理和行为等方面产生积极效应。且这些积极效应会受到物理环境、个体以及社会因素的影响。未来应突破“城市——自然”二元对立思想并加强积极效应的纵深研究;拓展研究群体;促进相关研究成果的实际应用。  相似文献   
85.
Within the framework of modern evolutionary theory, arguments are reviewed that the nonlegal equivalent of aggressive criminal behavior may have evolved by natural selection among mammals, particularly primates, as part of their overall approach to reproduction. If so, the commission of aggressive crimes (or their nonlegal equivalent) by humans, and even efforts to prevent fellow social group members from being victimized by aggressive crimes, may also be partially explainable in natural selection terms. The plausibility of this deduction was explored, first, by specifying the three elements that a human act must have to be regarded as an aggressive crime. Summarily, these were that (1) injury to a victim must be a likely result of the act, (2) the act must be intended, and (3) the act must elicit negative responses from those witnessing it. The primate behavior literature was examined for evidence that some behavior of nonhumans met all three conditions. Affirmative results were obtained. Therefore, while further research is in order, human aggressive criminal behavior, as well as human efforts to control it, seem to have close parallels in other primates. This would be consistent with the notion that aggressive criminal behavior (along with its condemnation by fellow group members) is part of a social system produced and sustained by natural selection.  相似文献   
86.
87.
The association between the life orientation and attributional styles of a mother and the aggressiveness of her child were studied in 61 mothers and their children, 23 boys and 38 girls, mean age 6.6 years (range 4–13 years). The mother's life orientation and attributional styles were established during interviews using the life-style questionnaire, and a child's aggressiveness was evaluated by the mother using the Health Examination Survey. The factors assessing life orientation were lack of personal control, causal unstability, internal locus of causality, personal responsibility, and democratic educational attitudes. The mother's personal responsibility and internal causal attributions were related to nonaggressiveness in the child, whereas mothers with a lack of personal control were likely to have aggressive children. Educational attitudes were of no importance. The results showed no sex- or age-related variance.  相似文献   
88.
High levels of risk perception of terrorism (RPT) may impair an individual's quality of life and welfare. To understand the mechanisms responsible for RPT, this study investigated the association of gender and coping styles with individual differences in two key elements of RPT: perceived control and perceived vulnerability. A convenience sample of 400 Israelis (181 men and 219 women) filled out questionnaires on sociodemographic background, RPT and coping. Employing a multidimensional approach for coping, we divided participants into four coping types: problem-focused (n = 65), emotion-focused (n = 70), mixed (n = 122) and minimal (n = 142). The results indicate that problem-focused coping is associated with higher levels of perceived control than other types of coping and mixed coping is associated with higher levels of perceived vulnerability than other coping strategies. Also, interactions between gender and exposure to terrorism contributed to understanding the differences in perceived control. The discussion addresses gender differences in RPT and coping in the context of traditional gender roles. The study concludes with implications for risk management and therapeutic interventions regarding high levels of fear of terrorism.  相似文献   
89.
Perfectionism and impulsivity are multidimensional constructs. While different perfectionism dimensions are exclusively measured through self-reports, different impulsivity dimensions can be measured through self-report or behaviour via preferences for different rewards. This study explored differential associations between perfectionism and impulsivity based on both dimension and measurement modality (self-report/behavioural). We then examined whether adaptive or maladaptive perfectionism would be differentially associated with impulsivity. Two-hundred and six students completed two perfectionism and three impulsivity measures (two self-report; one behavioural). Two self-report impulsivity measures were associated with specific perfectionism dimensions, whereas the behavioural measure was not associated with perfectionism. Maladaptive perfectionism was associated with decreasing impulsivity, whereas adaptive perfectionism was associated with increasing impulsivity. Perfectionism related to impulsivity differently depending on how each construct was measured.  相似文献   
90.
Children with feeding disorders often engage in refusal behavior to escape or avoid eating. Escape extinction combined with reinforcement is a well-established intervention to treat food refusal. Physical guidance procedures (e.g., jaw prompt, finger prompt) have been shown to increase food acceptance and decrease inappropriate mealtime behavior when more commonly employed escape extinction (e.g., nonremoval of the spoon) procedures are ineffective. The finger prompt, however, has not been extensively evaluated as a treatment adjunct to target food refusal, thus necessitating further examination. The purpose of this prospective study was to assess a variation of a finger prompt procedure to treat food refusal and to assess caregivers' acceptability of the procedure. Three children age 1 to 4 years admitted to an intensive feeding disorders program and their caregivers participated. The finger prompt was effective in increasing bite acceptance across all participants and decreasing or maintaining low levels of inappropriate behavior for 2 participants. The procedure was also acceptable to all caregivers.  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