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   19413篇
  免费   183篇
  国内免费   275篇
教育   13341篇
科学研究   2697篇
各国文化   61篇
体育   970篇
综合类   449篇
文化理论   428篇
信息传播   1925篇
  2024年   4篇
  2023年   10篇
  2022年   97篇
  2021年   233篇
  2020年   163篇
  2019年   103篇
  2018年   2268篇
  2017年   2184篇
  2016年   1648篇
  2015年   355篇
  2014年   451篇
  2013年   586篇
  2012年   768篇
  2011年   1309篇
  2010年   1390篇
  2009年   942篇
  2008年   1157篇
  2007年   1703篇
  2006年   656篇
  2005年   873篇
  2004年   711篇
  2003年   654篇
  2002年   448篇
  2001年   274篇
  2000年   255篇
  1999年   134篇
  1998年   86篇
  1997年   105篇
  1996年   92篇
  1995年   46篇
  1994年   31篇
  1993年   33篇
  1992年   26篇
  1991年   15篇
  1990年   8篇
  1989年   20篇
  1988年   10篇
  1987年   2篇
  1986年   6篇
  1985年   1篇
  1984年   4篇
  1983年   2篇
  1979年   2篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1957年   2篇
  1946年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
This article examines the construct validity of the Course Experience Questionnaire (CEQ) in Hong Kong and investigates the similarities and differences in the process of learning among students in different disciplinary studies. It is based on a survey of 1,563 undergraduate students in two disciplines, humanities and sciences, and of principally Chinese ethnicity. Findings from exploratory and confirmatory factor analyses support the scale structure of the four subscales of a modified version of the CEQ (good teaching, clear goals and standards, appropriate work, and appropriate assessment) in a non-Western context and could provide a basis for cross cultural research and international benchmarking. While there was variation across subgroups, there was a genuine pattern of relationships between the perceptions of learning environment and learning strategies shown by structural modeling. This information could be used to inform the design of discipline-specific programs in the new curriculum.  相似文献   
992.
Quantitative trait loci (QTL) analysis was conducted in bread wheat for 14 important traits utilizing data from four different mapping populations involving different approaches of QTL analysis. Analysis for grain protein content (GPC) sug- gested that the major part of genetic variation for this trait is due to environmental interactions. In contrast, pre-harvest sprouting tolerance (PHST) was controlled mainly by main effect QTL (M-QTL) with very little genetic variation due to environmental interactions; a major QTL for PHST was detected on chromosome arm 3AL. For grain weight, one QTL each was detected on chromosome arms 1AS, 2BS and 7AS. QTL for 4 growth related traits taken together detected by different methods ranged from 37 to 40; nine QTL that were detected by single-locus as well as two-locus analyses were all M-QTL. Similarly, single-locus and two-locus QTL analyses for seven yield and yield contributing traits in two populations respectively allowed detection of 25 and 50 QTL by composite interval mapping (CIM), 16 and 25 QTL by multiple-trait composite interval mapping (MCIM) and 38 and 37 QTL by two-locus analyses. These studies should prove useful in QTL cloning and wheat improvement through marker aided selection.  相似文献   
993.
The aim of this study was to research the changes in cytotoxicity and antibacterial properties after silver nanoparticles (AgNPs) were incorporated into the surface coating of dental alloys. AgNPs were attached to cobalt chromium alloys and pure titanium using a hydrothermal method, according to the reaction: AgNO3+NaBH4→ Ag+1/2H2+1/2B2H6+NaNO3. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of the alloys when in contact with osteogenic precursor cells (MC3T3-E1) from mice and mesenchymal stem cells (BMSC) from rats. The antibacterial properties of dental alloys incorporating three different concentrations (10, 4, and 2 μmol/L) of AgNPs were tested on Staphylococcus aureus (SA) and Streptococcus mutans (MS). High cytotoxicity values were observed for all dental alloys that contained 0% of AgNPs (the control groups). The incorporation of AgNPs reduced cytotoxicity values. No significant difference was observed for antibacterial performance when comparing dental alloys containing AgNPs to the respective control groups. The results demonstrated that the cobalt chromium alloys and pure titanium all had cytotoxicity to MC3T3-E1 and BMSC and that the incorporation of AgNPs could reduce this cytotoxicity. The concentrations of AgNPs adopted in this study were found to have no antibacterial action against SA or MS.  相似文献   
994.
The objectives of the present study were to ascertain the variations in the serum levels of malondialdehyde and total antioxidant status, in head and neck malignancies with different stages, with and without oral antioxidant supplementation, before and after radiotherapy, and to validate the protective effects of an antioxidant supplementation during radiotherapy. The pretreatment values of serum malondialdehyde were significantly raised, while that of serum total antioxidant status were significantly declined in all the stages of head and neck malignancies, when compared with the healthy controls values (P<0.001). A significant correlation was observed related to the studied parameters and different stages of the disease. The study suggests that an oral antioxidant supplementation during radiotherapy is an effective mode in reducing oxidative stress. Antioxidant supplementation during radiotherapy may serve as an adjuvant therapy in malignancies offering a protection to normal cells that may further reduce the risk of developing secondary cancers.  相似文献   
995.
The initiatives attempting to forge links between the academia and the industry flourished in France after World War I. The so-called “industrial institutes” shared a common goal: to reinvigorate the French economy through science. Because of their focus on applied research, they differed from traditional engineering schools that usually neglected laboratory work and innovation. However, while the industrial institutes were a distinct category that shows broader trends in science-industry relations, from a formal point of view they did not constitute a coherent category. The term “institute” was ambiguous and applied to various legal and administrative arrangements. While the French state attempted to unify terminology by introducing “faculty institutes” through the 1920 Decree on the constitution of universities, the measure was not sufficient to englobe all types of institutions. The diversity of organizational realities behind the industrial institutes is, however, useful for analyzing power structures and hierarchies in a given industrial sector. The legal form of an industrial institute was conditioned by the state and the robustness of the industry that funded it. As such, the history of the French industrial institutes may constitute a fertile ground for broader analyses on the impact of power relations on the legal reality behind the initiatives uniting science and industry.  相似文献   
996.
997.
998.
999.
文章采用文献资料法和访问调查法,对提高武术选项课教学质量的有效途径进行了探讨。认为抓好武术基本功教学是提高武术选项课教学质量的基础;按武术攻防技击性特点教学是关键;采用灵活多样的教学方法是前提;熟悉教材、编写好教案是重要环节。  相似文献   
1000.
Book Notices     
Steven French 《Metascience》2007,16(1):175-177
  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