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   21535篇
  免费   226篇
  国内免费   252篇
教育   14544篇
科学研究   3117篇
各国文化   32篇
体育   1117篇
综合类   689篇
文化理论   442篇
信息传播   2072篇
  2024年   4篇
  2023年   14篇
  2022年   155篇
  2021年   353篇
  2020年   232篇
  2019年   137篇
  2018年   2274篇
  2017年   2224篇
  2016年   1699篇
  2015年   487篇
  2014年   621篇
  2013年   764篇
  2012年   939篇
  2011年   1471篇
  2010年   1586篇
  2009年   1093篇
  2008年   1313篇
  2007年   1843篇
  2006年   730篇
  2005年   972篇
  2004年   766篇
  2003年   645篇
  2002年   444篇
  2001年   278篇
  2000年   174篇
  1999年   157篇
  1998年   132篇
  1997年   112篇
  1996年   90篇
  1995年   56篇
  1994年   58篇
  1993年   48篇
  1992年   43篇
  1991年   24篇
  1990年   19篇
  1989年   14篇
  1988年   5篇
  1986年   3篇
  1985年   6篇
  1984年   5篇
  1983年   4篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1967年   1篇
  1959年   1篇
  1957年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
在高校思想政治工作中,美育可以起到道德感化、人生向导、开发智力的作用.强化高校思想政治工作的内容美、形式美和形象美,对于增强思想政治工作的吸引力,提高思想政治工作的成效具有积极意义.  相似文献   
232.
INTRODUCTION There is increased need in recent years for strengthening or rehabilitation of existing reinforced concrete structures adversely affected by overloading, construction material deterioration, seismic loads, structural deformation, etc. An effective method for increasing the shear capacity of reinforced concrete columns is the use of externally bonded carbon fiber reinforced plastic (CFRP) systems (ACI, 2002). FRP systems were first applied to reinforced concrete col-umns i…  相似文献   
233.
A pre-treatment methodology for clenbuterol hydrochloride (CLEN) isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers (MIPs). CLEN-imprinted polymers were synthesized by the combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA) as the binary functional monomers. MAA-linked allyl-β-CD MIPs (M-MAA) were characterized by Fourier transform-infrared (FT-IR) spectroscopy and a scanning electron microscope (SEM). Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MISPE) micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation (RSD) ≤4.45%.  相似文献   
234.
Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation.  相似文献   
235.
多元文化背景下学校德育的文化应答   总被引:5,自引:0,他引:5  
当前,文化的多元化越来越被人们所认同。在这种文化多元化、价值取向多元化的背景下,学校德育陷入困境。选择文化学的视角,基于多元文化发展的要求理性地反思我国学校德育的现状,根据社会发展及人自身发展的要求做出应答,有助于从新的视角为提高德育实效做出努力。  相似文献   
236.
本文从大学文化建设的视角 ,在认真分析我国大学素质教育现状的基础上 ,指出基于教育创新的大学文化建设必须把推进大学素质教育贯穿始终 ,必须充分体现素质教育对人的全面发展和社会可持续发展的深远意义 ,并提出了六项加强素质教育的具体对策。  相似文献   
237.
238.
An excellent airfoil with a high lift-to-drag ratio may decrease oil consumption and enhance the voyage. Based on NACA 0012, an improved airfoil is explored in this paper. The class/shape function transformation has been proved to be a good method for airfoil parameterization, and in this paper it is modified to improve imitation accuracy. The computational fluid dynamics method is applied to obtain numerically the aerodynamic parameters of the parameterized airfoil, and the result is proved credible by comparison with available experimental data in the open literature. A polynomial-based response surface model and the uniform Latin hypercube sampling method are employed to decrease computational cost. Finally, the nonlinear programming by quadratic Lagrangian method is utilized to modify the multi-island genetic algorithm, which has an improved optimization effect than the method used on its own. The obtained result shows that the modified class/shape function transformation method produces a better imitation of an airfoil in the nose and tail regions than the original method, and that it will satisfy the tolerance zone of the model in a wind tunnel. The response surface model based on the uniform Latin hypercube sampling method gives an accurate prediction of the lift-to-drag ratio with changes in the design variables. The numerical result of the flow around the airfoil shows reasonable agreement with the experimental data graphically and quantitatively. Ultimately, an airfoil with better capacity than the original one is acquired using the multi-island genetic algorithm based nonlinear programming by quadratic Lagrangian optimization method. The pressure contours and lift-to-drag ratio along with the attack angle have been compared with those of the original airfoil, and the results demonstrate the strength of the optimized airfoil. The process for exploring an improved airfoil through parameterization to optimization is worth referencing in future work.  相似文献   
239.
郁华  陆建身 《生物学教学》2006,31(10):15-17
当前,生物学与数理方法的结合变得更加紧密,生物学科研需要运用统计学原理和方法来进行定性和定量研究,并进行科学的试验设计。但是在运用的同时,有时也会犯一些错误。下面是几个比较普遍和有代表性的问题。  相似文献   
240.
Teacher performance evaluation currently is receiving unprecedented attention from policy makers, scholars, and practitioners worldwide. This study is one of the few studies of teacher perceptions regarding teacher performance measures that focus on China. We employed a quantitative dominant mixed research design to investigate Chinese teachers’ preferences for teacher performance measures and the possible reasons for their preferences. Considering the quantitative results, the surveyed Chinese teachers identified fulfillment of additional roles, collaboration with faculty and staff, and students’ test scores as the most important measures for performance evaluation. Qualitatively, the most important measures that the surveyed teachers reported were the teacher’s morality, workload, and students’ test scores.  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