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   2648篇
  免费   263篇
  国内免费   720篇
  2024年   10篇
  2023年   29篇
  2022年   56篇
  2021年   92篇
  2020年   103篇
  2019年   82篇
  2018年   101篇
  2017年   120篇
  2016年   78篇
  2015年   83篇
  2014年   73篇
  2013年   232篇
  2012年   167篇
  2011年   223篇
  2010年   188篇
  2009年   194篇
  2008年   208篇
  2007年   296篇
  2006年   277篇
  2005年   244篇
  2004年   160篇
  2003年   117篇
  2002年   72篇
  2001年   57篇
  2000年   44篇
  1999年   63篇
  1998年   34篇
  1997年   32篇
  1996年   26篇
  1995年   27篇
  1994年   18篇
  1993年   22篇
  1992年   9篇
  1991年   7篇
  1990年   9篇
  1989年   9篇
  1988年   9篇
  1987年   4篇
  1986年   11篇
  1985年   8篇
  1984年   10篇
  1983年   7篇
  1982年   6篇
  1981年   5篇
  1980年   6篇
  1979年   3篇
排序方式: 共有3631条查询结果,搜索用时 15 毫秒
231.

The average velocities of screw dislocations in Ni 3 Al single crystals have been directly measured as a function of resolved shear stress (RSS) and orientation in the temperature domain of the flow stress anomaly using the etch-pit technique. The velocity was found to be extremely sensitive to the RSS in all cases. In contrast with ordinary metals, the screw dislocation velocities in Ni 3 Al show anomalous behaviour; under a constant RSS, the velocities decrease dramatically with increasing temperature. Furthermore, the velocities and the tension-compression asymmetry of the velocities depend on the orientation of applied stress.  相似文献   
232.
The aggregation behavior of Au atoms and atomic islands on silicone oil surfaces has been systematically investigated by analyzing the evolution of surface coverage. The apparent Au surface coverage increases linearly with the nominal film thickness at low thicknesses and the rate of increase is almost independent of deposition flux. However, as the deposition flux increases, the surface coverage goes up linearly. Further analysis reveals that the deposition flux strongly affects the system free-energy of the island-oil system and therefore the aggregation behavior of the Au atoms and islands.  相似文献   
233.

In this letter, the dislocation patterns on the common primary slip plane in a fatigued \[1-34]-\[182-7] copper bicrystal with a Sigma=19b grain boundary (GB) have been investigated using the electron channelling contrast technique in a scanning electron microscope. The results show that the two-phase dislocation structure, such as veins and persistent slip band (PSB) walls, embedded within veins, can be clearly seen on the common primary slip plane. In particular, the interactions of PSBs with the GB are clearly revealed. It is found that there are three kinds of interaction mode between the GB and the dislocations during cyclic deformation, and those are discussed. It is suggested that the dislocations carried by PSBs cannot transfer through the GB continuously even though the bicrystal has a common primary slip plane and its surface slip bands are continuous across the GB.  相似文献   
234.
Childhood maltreatment places individuals, including African American women who are undereducated and economically disadvantaged, at risk for developing posttraumatic stress disorder (PTSD) symptoms. Participants were 192 African American women with a history in the prior year of both a suicide attempt and intimate partner violence (IPV) exposure. They were recruited from a public hospital that provides medical and mental health treatment to mostly low-income patients. A simple mediator model was used to examine if (a) existential well-being (sense of purpose) or religious well-being (relationship with God) mediated the link between childhood maltreatment and adult PTSD symptoms. Sequential multiple mediator models determined if physical and nonphysical IPV enhanced our understanding of the mediational association among the aforementioned variables. Findings suggest that existential well-being mediated the association between childhood maltreatment and adult PTSD symptoms in a simple mediator model, and existential well-being and recent nonphysical IPV served as sequential multiple mediators of this link. However, religious well-being and physical IPV were not significant mediators. Findings underscore the importance of enhancing existential well-being in the treatment of suicidal African American women with a history of childhood maltreatment and IPV.  相似文献   
235.
颜色概念的知觉符号表征与命题符号表征   总被引:1,自引:0,他引:1  
使用启动范式通过两个实验检验颜色概念的表征是知觉符号表征还是命题符号表征.实验l使用显性颜色概念,即颜色词;实验2使用隐性颜色概念,即隐含颜色信息的词.实验结果表明显性颜色概念的表征是知觉符号表征,而隐性颜色概念的表征是命题符号表征.  相似文献   
236.
根据教育出版社编辑工作特征,运用调查研究法、特尔菲(Delphi)专家评价法等,编制了编辑胜任力调查量表,通过对分布在全国的7个教育出版社301名编辑问卷测试,并对测试数据采用因素分析与验证分析的方法进行了系统分析,建构了教育编辑胜任力模型。研究结果表明,教育编辑胜任力主要由工作取向、自我取向、人际取向3方面8个因子构成。本研究为教育出版社的优秀编辑的培养、选拔及测评方面提供了新的理论依据。  相似文献   
237.
采用家庭功能与同伴行为模式问卷和学习自我调节问卷,对913名青少年进行了测试。考察青少年同伴行为模式的发展特点,以及同伴行为模式在家庭功能与青少年学习自我调节关系中的中介作用。结果表明:青少年同伴行为模式对学习支持度随年级升高而下降;随年级升高,青少年在学习自我调节各维度上及总分的平均分越来越低;青少年的同伴行为模式可以正向预测学习自我调节,并在家庭功能与学习自我调节之间起部分中介的作用。家庭功能除直接影响学习自我调节外,还通过青少年的同伴行为模式间接影响他们的学习自我调节。  相似文献   
238.
应用工作压力、职业枯竭和职业承诺问卷对中小学教师2114人进行调查,主要探讨职业承诺对工作压力与职业枯竭关系的调节效应。结果发现:工作压力与职业枯竭的情绪衰竭、非人性化、认知枯竭具有显著正相关,情感承诺、规范承诺与职业枯竭具有显著负相关;教师职业承诺以及所包括的情感承诺、留职承诺、规范承诺对工作压力与职业枯竭关系具有负向调节效应;不同教龄段教师在职业枯竭不同方面存在差异。  相似文献   
239.
偏离行为的研究在社会学和组织行为学领域都有较丰富的成果,然而其关注点主要集中于对社会或组织产生负面作用的消极偏离行为。近年来相关领域的学者越来越关注积极偏离行为(Positive Deviance, PD)的研究。该文综述了关于积极偏离行为的定义的各方观点,同时分析了积极偏离行为与相似构念的差异,并综述了积极偏离行为的测量方式,以及积极偏离行为的前因变量和结果变量。最后对积极偏离行为未来的研究方向进行了展望。  相似文献   
240.
This study examined associations between self-reported mental health problems, body image, bullying victimisation and school safety in large adolescent samples in Japan and Russia, considering the effects of gender, culture and their interactions. In both Japan and Russia, girls reported a greater number of mental health problems, less bullying victimisation and much higher body dissatisfaction than boys did. Japanese adolescents rated themselves higher on total difficulties, reported less body dissatisfaction and bullying victimisation, and rated their school safety lower than that of Russian youths. Cross-cultural differences in total difficulties and body image were qualified by gender. Body dissatisfaction, bullying victimisation and school safety all independently contributed to adolescent mental health problems. The protective effect of school safety on total difficulties was larger for girls than for boys; the strength of the association between bullying victimisation and adolescent mental health problems differed across genders and cultures. The findings indicate a need for a cross-cultural approach and provide a strong basis for targeted interventions that seek to improve adolescent mental health.  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