全文获取类型
收费全文 | 11468篇 |
免费 | 2篇 |
专业分类
教育 | 8872篇 |
科学研究 | 1209篇 |
体育 | 334篇 |
文化理论 | 382篇 |
信息传播 | 673篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2170篇 |
2017年 | 2077篇 |
2016年 | 1563篇 |
2015年 | 105篇 |
2014年 | 111篇 |
2013年 | 68篇 |
2012年 | 215篇 |
2011年 | 688篇 |
2010年 | 831篇 |
2009年 | 427篇 |
2008年 | 637篇 |
2007年 | 1145篇 |
2006年 | 65篇 |
2005年 | 390篇 |
2004年 | 443篇 |
2003年 | 355篇 |
2002年 | 127篇 |
2001年 | 4篇 |
2000年 | 19篇 |
1997年 | 14篇 |
1995年 | 1篇 |
1991年 | 6篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1976年 | 1篇 |
1921年 | 1篇 |
1919年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
A method of using laser induced fluorescence(LIF)technique was applied to two-dimensional measurement of the liquid concentration distribution in the 250Y structured packing sheet. The experimental structured packing sheet was made of perspex so that the laser could pass through it. The visualization of the distribution of the liquid concentration in the structured packing sheet was realized. The calibration of the thickness and liquid concentration was carried out firstly and the regression formula I=kcd was acquired, in which concentration c and the liquid film thickness d were both considered. Then the liquid feed of uniform tracer(rhodamine)concentration entered the perspex structured packing from the top under different spraying densities. The corresponding thickness of liquid film on the packing was calculated. Finally, tracer(rhodamine)with a high concentration was injected only at one fixed point of the structured packing under different spraying densities of the liquid. With the known liquid film thickness, the concentration distribution of the tracer can be calculated inside the structured packing sheet. 相似文献
142.
143.
Laura Goodwin Elizabeth Kozleski Rodney Muth Lynn K. Rhodes Kim Kennedy White 《Innovative Higher Education》2005,30(4):251-268
This article describes the establishment in fall 2002 of a School of Education Research Center designed to support faculty
in increasing productivity and quality in research. Details are provided about center goals, services, staffing, space, resources,
and logistics during the first year of operation. In addition, data are shared about faculty usage of the Center, the level
of faculty satisfaction with center services in the first year, and initial increases in faculty productivity. The article
concludes with plans for continued data collection to monitor the impact of the Center, a discussion of lessons learned at
this point in the Center's development, and possibilities for the evolution of the Center.
All authors are at the University of Colorado, Denver. Laura Goodwin, Ph.D., University of Colorado at Boulder, is Interim
Associate Vice Chancellor for Faculty Affairs and continues to serve as a Faculty Research Associate. Elizabeth Kozleski,
Ed.D., University of Northern Colorado, is the Associate Dean for Research in the School of Education. Lynn Rhodes, Ed.D.,
Indiana University, is the Dean of the School of Education. Rodney Muth, Ph.D., Claremont Graduate School, is a professor
of Administrative Leadership and Policy Studies in the school and chaired the Research Center Advisory Board. Kim Kennedy
White, M.A., University of Oregon, was the original School of Education Research Center Coordinator and was responsible for
collecting most of the data included in this study. 相似文献
144.
1IntroductionBackground subtraction methods are extensively ex-ploited for moving object detection in videos in manyapplications ,such as traffic monitoring[1],human mo-tion capture[2]and video surveillance[3]. The centralidea behind such methods is to segment foreground ini mage sequences taken from a fixed camera by com-paring each newframe to a model of the scene back-ground . Therefore , correctly and efficiently modelingand updating the background model is one of the mostchallenging aspec… 相似文献
145.
1 Introduction Organiclight emittingdiodes(OLEDs)haveattract edconsiderableattentionduetoitsgreatpotentialinefficiency ,low voltage ,large area ,lightweight ,andfull colorflat paneldisplays[1,2 ] .Forfull colordis plays ,itisnecessarytohaveefficientred ,green ,andblueemitterswithappropriatechromaticity .Bycom parisonwiththehighperformanceofblueandgreenOLEDs ,theperformanceandpurechromaticityofredOLEDsarestillrelativelypoor .UsuallyredOLEDsareimprovedbydopingreddyesintohostmaterialswit… 相似文献
146.
Drew Polly Christie S. Martin Jennifer R. McGee Chuang Wang Richard G. Lambert David K. Pugalee 《Early Childhood Education Journal》2017,45(5):659-669
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
147.
Kausalai Wijekumar Bonnie J. F. Meyer Puiwa Lei Anita C. Hernandez Diane L. August 《Reading and writing》2018,31(9):1969-1996
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
148.
149.
150.
Yue-qin Qiu Xue-fen Yang Xian-yong Ma Yun-xia Xiong Zhi-mei Tian Qiu-li Fan Li Wang Zong-yong Jiang 《Journal of Zhejiang University. Science. B》2017,18(6):492-500
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