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   1467篇
  免费   124篇
  国内免费   135篇
  1726篇
  2024年   11篇
  2023年   24篇
  2022年   30篇
  2021年   46篇
  2020年   69篇
  2019年   75篇
  2018年   83篇
  2017年   87篇
  2016年   99篇
  2015年   63篇
  2014年   62篇
  2013年   242篇
  2012年   49篇
  2011年   70篇
  2010年   37篇
  2009年   62篇
  2008年   69篇
  2007年   57篇
  2006年   66篇
  2005年   42篇
  2004年   40篇
  2003年   32篇
  2002年   29篇
  2001年   41篇
  2000年   26篇
  1999年   19篇
  1998年   14篇
  1997年   10篇
  1996年   13篇
  1995年   9篇
  1994年   6篇
  1993年   9篇
  1992年   10篇
  1991年   4篇
  1990年   16篇
  1989年   8篇
  1988年   7篇
  1987年   10篇
  1986年   8篇
  1985年   6篇
  1984年   5篇
  1983年   7篇
  1982年   7篇
  1981年   4篇
  1980年   8篇
  1979年   6篇
  1978年   11篇
  1977年   8篇
  1976年   10篇
排序方式: 共有1726条查询结果,搜索用时 15 毫秒
241.
242.
The aim of this study was to explore the longitudinal relation between internalizing symptoms and academic achievement, as two processes of children and youth development, among children in Norway, and whether having an immigrant background moderated this association. Data collected from 4,458 students in Norway in four waves over three years were analyzed with multi‐group latent growth curve modeling (LGM ). Results showed that internalizing symptoms level remained unchanged over time both for immigrant and non‐immigrant children, while levels of academic achievement increased only for children of immigrants with both parents born outside of Norway. Further analyses supported a reciprocal relation between internalizing symptoms and academic achievement and revealed that the initial level of academic achievement predicted the rate of change in internalizing symptoms over time, but not vice versa. Moreover, immigrant background did not moderate the associations in the model, however, children of immigrants with both parents born abroad initially had lower levels of academic achievement, but showed an increase in academic achievement, compared to their non‐immigrant peers as well as to peers with one native‐born parent after controlling for gender and their grade at the first observation. The implications for policy and practice were discussed.  相似文献   
243.
We consider multi‐set data consisting of observations, k = 1,…, K (e.g., subject scores), on J variables in K different samples. We introduce a factor model for the J × J covariance matrices , k = 1,…, K, where the common part is modelled by Parafac2 and the unique variances , k = 1,…, K, are diagonal. The Parafac2 model implies a common loadings matrix that is rescaled for each k, and a common factor correlation matrix. We estimate the unique variances by minimum rank factor analysis on for each k. The factors can be chosen orthogonal or oblique. We present a novel algorithm to estimate the Parafac2 part and demonstrate its performance in a simulation study. Also, we fit our model to a data set in the literature. Our model is easy to estimate and interpret. The unique variances, the factor correlation matrix and the communalities are guaranteed to be proper, and a percentage of explained common variance can be computed for each k. Also, the Parafac2 part is rotationally unique under mild conditions.  相似文献   
244.
The directional solidification process of ternary Ag42.4Cu21.6Sb36 eutectic alloy within a wide growth rate range from 2 to 60 μm/s was accomplished at a constant temperature gradient of 50 K/cm. As growth rate increases, the ternary (θ(Cu2Sb) + ε(Ag3Sb) + Sb) eutectic morphology evolves from “lamellar (θ + ε) plus fibrous (Sb)” structure into “(θ + Sb) fibres in continuous ε matrix” structure. The θ and (Sb) phase spacings decrease with the increase of growth rate according to power functions with exponent values of 0.55 and 0.56, respectively. It is also found that the microhardness of directionally solidified Ag42.4Cu21.6Sb36 alloy samples is enhanced with the increase of growth rate, and the decrease of θ and (Sb) phase spacings.  相似文献   
245.
研究甲状腺癌组织中趋化因子4受体(CXCR4)和趋化因子7受体(CXCR7)的表达情况及临床病理意义。应用免疫组织化学PV-6000法及Westernblot法检测CXCR4与CXCR7在甲状腺癌中的表达。二者在甲状腺癌与甲状腺良性疾病组织的差异均具有统计学意义(P〈0.05),在甲状腺癌中表达仅与淋巴结转移有关(P〈0.05),CXCR4与CXCR7之间呈正相关。Westernblot结果提示二者在甲状腺癌中的表达率高于癌旁及甲状腺腺瘤。CXCR4和CXCR7的表达水平与淋巴结转移相关,可作为甲状腺癌预后的判断指标。  相似文献   
246.
双因子模型:多维构念测量的新视角   总被引:1,自引:0,他引:1       下载免费PDF全文
顾红磊  温忠粦  方杰 《心理科学》2014,37(4):973-979
双因子模型是一种既有全局因子又有局部因子的模型,近年来有了许多应用。本文讨论了双因子模型和高阶因子模型在数学模型、参数之间的关系,概念上和应用上的差异;概述了双因子模型在信度研究、平衡量表、探索性因子分析和项目反应理论中的应用。作为例子,在Rosenberg自尊量表结构的研究中,通过双因子模型分析了自尊特质效应与项目表述方法效应。  相似文献   
247.
为比较替格瑞洛与氯吡格雷对急性ST段抬高型心肌梗死(STEMI)患者急诊经皮冠状动脉介入术(PCI)术后炎症因子的影响,将176例急性STEMI且行急诊PCI术的患者分为替格瑞洛组(A组)58例、氯吡格雷常规组(B组)58例、氯吡格雷强化组(C组)60例,分别测定术前、术后12小时、术后7天、术后1个月、术后3个月、6个月时炎症因子e反应蛋白(CRP)、白细胞介素-6(IL6)、髓过氧物酶(MPO)、可溶性CD40受体(sCD40L)的含量,比较3组患者各炎症因子在不同时间点有无统计学差异。结果显示c组和A组较B组明显降低(P〈0.05),有统计学意义,而A组较c组稍降低(P〉0.05),但两者无统计学意义。由此可见,替格瑞洛的抗炎作用较常规剂量氯吡格雷作用明显增强,和强化剂量氯吡格雷作用相仿。  相似文献   
248.
249.
为考察当代中国青少年理想的现状及其影响因素,研究采用当代青少年理想调查问卷对全国12个省份的5000名青少年进行调研,结果发现当代中国青少年的理想水平较高,其中男生在身体理想方面的水平高于女生,在道德、人格、学业、生活和职业等理想方面的水平低于女生;初中生在道德、人格、生活和社会等理想方面的水平高于高中和大学低年级学生,在物质、身体、学业和职业等理想方面的水平低于大学低年级学生,而高中生的学业和职业理想的水平低于初中生和大学低年级学生。回归分析发现,父亲文化程度能够正向预测青少年的职业理想,母亲文化程度对青少年的生活理想有负向预测作用,家庭收入对青少年的物质、生活和身体理想有显著的正向预测作用。  相似文献   
250.
Research on self‐compassion, which is defined as being understanding and kind to oneself when confronted with negative experiences, has produced an impressive number of articles in recent years. This research shows that individual differences in self‐compassion, as measured by the Self‐Compassion Scale (SCS), are positively related to life satisfaction, health and social functioning. However, a critical and systematic test of self‐compassion from a personality perspective has not yet conducted so far. In the present study (N = 576), we (i) tested the factor structure of the SCS, (ii) examined the distinctiveness of self‐compassion with regard to the five‐factor model of personality, focusing on neuroticism, and (iii) tested the incremental predictive power of self‐compassion beyond the five‐factor model in the context of life satisfaction. Confirmatory factor analyses supported a two‐factor plus six facets solution of self‐compassion (a positive factor and a negative factor). Additional analyses revealed that the negative factor was redundant with facets of neuroticism (rs ≥ .85), whereas the positive factor had some unique variance left. However, neither the negative factor nor the positive factor could explain substantial incremental variance in life satisfaction beyond neuroticism. Recommendations for how to use the SCS are provided, and the future of research on self‐compassion is discussed. Copyright © 2017 European Association of Personality Psychology  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