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   17673篇
  免费   126篇
  国内免费   176篇
教育   12348篇
科学研究   2439篇
各国文化   44篇
体育   806篇
综合类   403篇
文化理论   416篇
信息传播   1519篇
  2024年   2篇
  2023年   7篇
  2022年   69篇
  2021年   194篇
  2020年   134篇
  2019年   67篇
  2018年   2240篇
  2017年   2129篇
  2016年   1618篇
  2015年   305篇
  2014年   414篇
  2013年   412篇
  2012年   658篇
  2011年   1156篇
  2010年   1270篇
  2009年   853篇
  2008年   1011篇
  2007年   1577篇
  2006年   486篇
  2005年   727篇
  2004年   660篇
  2003年   607篇
  2002年   428篇
  2001年   296篇
  2000年   183篇
  1999年   112篇
  1998年   82篇
  1997年   70篇
  1996年   51篇
  1995年   30篇
  1994年   35篇
  1993年   14篇
  1992年   19篇
  1991年   17篇
  1990年   3篇
  1989年   10篇
  1988年   4篇
  1987年   1篇
  1986年   4篇
  1985年   3篇
  1984年   8篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1976年   1篇
  1957年   4篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
221.
本研究对上海市初三学生及家长进行了抽样问卷调查和学生英语测试,并以此为基础,研究家庭、学校、学生三大教育社会学因素与基础英语教育效果的关系。研究结果一方面证实了三大因素中多数子因素对英语教育效果的显著积极主效应和相互效应,另一方面也拒绝了普遍认为某些子因素积极作用于英语教育效果的假设。  相似文献   
222.
This study examines the influence of a year-long mathematics professional development program on Kindergarten teachers’ beliefs, content knowledge, instructional practices, and their students’ achievement. The professional development program is grounded in the theoretical construct of learner-centered professional development and focuses on supporting teachers’ integration of standards-based pedagogies aligned with the Common Core State Standards in Mathematics. Data analysis included examining 15 Kindergarten teachers’ mathematics content knowledge, their beliefs about mathematics, their enactment of student-centered pedagogies, and student achievement on curriculum-based assessments. Findings indicated that teachers adopted more student-centered pedagogies and embraced more student-centered beliefs about mathematics teaching during their time in the project. Further, Kindergarten teachers also demonstrated gains in their mathematical content knowledge, and those content knowledge gains were linked to gains in student achievement.  相似文献   
223.
Reading and comprehending content area texts is important for academic and professional success as well as life skills necessary to maintain good health and quality lifestyle. Spanish speaking English language learners have shown poor performance on high-stakes assessments in reading comprehension. The number of Spanish speaking English learners (ELs) in our schools continues to increase at a fast pace, and therefore it is imperative that we address their reading comprehension needs swiftly and effectively. The text structure strategy has shown positive results on comprehension outcomes in many research studies with students at Grades 2, 4, 5, and 7. This study is the first implementation of instruction about the text structure strategy expressly designed to accommodate the linguistic and comprehension needs of Spanish speaking ELs in Grades 4 and 5. Strategy instruction on the web for English learners (SWELL) was designed to deliver instruction about the text structure strategy to Spanish speaker English learners. A randomized controlled study with pre and post-tests was conducted with 14 classrooms at fourth-grade and 17 classrooms at fifth-grade in high poverty schools where over 85% of students were Spanish speaking bilinguals or ELs. Analysis of data using multi-level models show moderate to large-effects favoring the students in the SWELL classrooms over the business as usual control classrooms on important measures such as a standardized reading comprehension test and main idea and cloze tasks. This research has practical implications for the use of web-based tools to provide high-quality and supportive instruction to improve Spanish speaking ELs reading comprehension skills.  相似文献   
224.
瑞士酒店教育历史悠久、世界闻名,其主要特点是以行业为主导,理论联系实际,“校店合一”,工学结合,课程定位明确,教学严格规范,注重“双师”建设和学生创新能力的培养,强调教育的标准化与国际化。  相似文献   
225.
226.
227.
The expression of the cell death-inducing DNA fragmentation factor α-like effector (CIDE) family including Cidea, Cideb, and Cidec was significantly increased in mouse and human models of obesity. However, there was less information on these genes’ expression in pigs. Here, we hypothesized that different fat accumulation between lean (Duroc×Landrace×Yorkshire gilts, DLY) and obese (Lantang) pigs was attributed to porcine CIDE-modulating lipid metabolism. Our data showed that Cidea and Cidec were expressed at a high level in adipose tissue, and at a relatively high level in skeletal muscle, whereas Cideb was mainly expressed in the liver in both breeds of pig. Lantang pigs had higher white adipose and skeletal muscle Cidea and Cidec mRNA abundance, and hepatic and muscle Cideb mRNA than DLY pigs. Lipid metabolism-related genes including sterol regulatory element binding protein 1c (SREBP-1c), hepatocyte nuclear factor-4α (HNF-4α), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), fatty acid synthase (FASN), diacylglycerol O-acyltransferase 1 (DGAT1), and DGAT2 showed a higher expression level in adipose tissue from obese pigs than in that from lean pigs. Lantang pigs exhibited higher mRNA abundance for liver SREBP-1c, HNF-4α, and PGC-1α, and higher skeletal muscle SREBP-1c, HNF-4α, PGC-1α, and DGAT2 expression, as compared with DLY pigs. However, the perlipin2 mRNA levels in adipose tissues, liver, and skeletal muscle were significantly lower in obese pigs than in their lean counterparts. Furthermore, plasma non-esterified fatty acid (NEFA), glucose, and triacylglycerol (TAG) levels were greater in obese pigs than in lean pigs. Finally, data from correlation analysis further found that CIDE mRNA expression was positively correlated with back fat thickness (BFT), abdominal fat mass (AFM), and the levels of NEFA, TAG, and glucose in the two breeds. Collectively, these data revealed that the porcine CIDEs possibly modulated lipid metabolism and contributed to the development of fat deposition and obesity in Lantang pigs.  相似文献   
228.
本文扼要介绍了众数的特点及其应用范围,给出了众数估计值计算公式的一种积分证明方法。  相似文献   
229.
Composite materials of Fe/Al2O3, which consist of small particles of iron supported by thermally stable alumina even at 500–700 °C, have been widely used in the water-gas shift reaction for natural gas reforming. Therefore, Fe/Al2O3 is one of the promising candidates for re-transformation of exhausted CO2 into fuels such as alcohols and hydrocarbons. The development of a CO2 reforming system using the composite materials of Fe/Al2O3 through CO2 reduction to CO, dissociation of water into hydrogen, and methanol synthesis has been investigated. It was found that dry and steam (i.e. wet) reforming of CO2 produced almost the same amount of CO. At a temperature above 500 °C, maximal and saturated yields of CO and H2 from CO2 and water were obtained. However, this CO2 reforming system requires higher-pressure conditions from several tens to hundreds standard atmospheric pressure in order to achieve high yield and selectivity for methanol production. In this study we developed the modified CO2 reforming system by the utilization of Ni and/or Cu instead of Fe in order to obtain other types of useful products such as CO, CH4, and carbon, more efficiently and selectively under atmospheric pressure. When Ni or Cu was used, conversion of CO2 was reduced to 76%, while 9% of methane was detected in the case of Ni. On the other hand, though the CO2 conversion reduced half of the Fe, the selectivity of CO from CO2 increased to 95% in the case of Cu.  相似文献   
230.
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