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   4443篇
  免费   49篇
教育   3214篇
科学研究   325篇
各国文化   66篇
体育   373篇
综合类   3篇
文化理论   52篇
信息传播   459篇
  2023年   18篇
  2022年   23篇
  2021年   45篇
  2020年   79篇
  2019年   132篇
  2018年   149篇
  2017年   140篇
  2016年   129篇
  2015年   86篇
  2014年   144篇
  2013年   1038篇
  2012年   103篇
  2011年   112篇
  2010年   94篇
  2009年   95篇
  2008年   96篇
  2007年   101篇
  2006年   114篇
  2005年   98篇
  2004年   91篇
  2003年   85篇
  2002年   71篇
  2001年   66篇
  2000年   75篇
  1999年   63篇
  1998年   68篇
  1997年   69篇
  1996年   47篇
  1995年   47篇
  1994年   43篇
  1993年   49篇
  1992年   38篇
  1991年   42篇
  1990年   52篇
  1989年   53篇
  1988年   48篇
  1987年   49篇
  1986年   45篇
  1985年   40篇
  1984年   45篇
  1983年   44篇
  1982年   32篇
  1981年   23篇
  1980年   27篇
  1979年   42篇
  1978年   29篇
  1977年   24篇
  1976年   25篇
  1974年   19篇
  1973年   20篇
排序方式: 共有4492条查询结果,搜索用时 31 毫秒
91.
92.
Blood zinc protoporphyrin (ZPP), serum total protein (TP), and total cholesterol (TC) levels in automobile workshop workers in relation to lead toxicity were analysed. In the present study, automobile workshop workers (healthy male workers at an age between 28 and 35 from four major automobile workshops in Kottayam, Kerala State, India) and the control (male healthy adults at an age between 28 and 35 residing at Aymanam, a distant village at Kottayam District, Kerala having reduced or no chance of lead exposure) displayed significant difference in blood lead (BPb) and blood ZZP (BZPP) level. The mean value of BPb in automobile workshop workers was 15.76±0.33 μg/dl, while in the control it was 8.20±0.15 μg/dl. In automobile workshop workers, the mean value of BZPP was 34.2±0.62 μg/dl. The control group exhibited a mean of 11.5±0.22 μg/dl. Automobile workshop workers exhibited significant increase in BZPP was corresponding to the increase in BPb level. The total protein levels estimated in automobile workshop workers showed significant decrease compared to control individuals, but was within the reference range of healthy individuals. The mean value of TP level in automobile workshop workers and control was 6.9±0.13 g/dl and 7.71±0.18 g/dl, respectively. There was no significant difference in blood haemoglobin (BHb) level among the automobile workshop workers and control. The serum TC level in automobile workshop workers showed significant decrease compared to the control individuals, but was with in the reference range of healthy individuals. The mean level of serum TC in automobile workshop workers was 162.00±3.44 mg/dl and the same in control was 172.86±4.32 mg/dl. The present study affirms occupational lead toxicity in automobile workshop workers and its effect on serum protein and cholesterol levels.  相似文献   
93.
Research on technological opportunity has typically focused on the impact of broad industry characteristics on R&D intensity of firms. This study complements such approaches by examining the impact of a multidimensional vector that measures technological opportunity on independent inventors’ decisions to patent and commercialize inventions. Using data from 559 inventions and controlling for demand, appropriability, and competitive conditions, we found two of four tested dimensions of technological opportunity - technical performance and technical uncertainty - to be significant and important determinants of the likelihood of commercialization. Technical feasibility appears important in affecting patenting but unimportant in affecting commercialization. Technical significance carries a negative, although insignificant, sign conditioning commercialization.  相似文献   
94.
Previous research has found that researchers rank journal reputation and impact factor (IF) amongst the key selection criteria when choosing where to submit. We explored the actual effect upon submission numbers of several possible factors. We retrieved 10 years of submission data from over a thousand journals, as well as data on IF, retractions, and other factors. We performed statistical analysis and identified correlations. We also undertook case study research on the 55 most significant submission decreases. We found a statistically significant correlation between changes in IF, ISI percentage ranking, and changes in submissions numbers in subsequent years. We also found a statistically significant effect on submission numbers in the year following the publication of a retraction. Our case studies identified other factors, including negative feedback on the peer review process. Our findings regarding IF confirm previous indications about the significance of IF on submissions. We explain the correlation with retractions through the concept of ‘peer review reputation’. These results indicate that editors and publishers need to focus on a journal's peer review practices, as well as a journal's IF, if they are to maintain and grow submissions.  相似文献   
95.
The following project aimed at promoting integrated and long-lasting learning is described for an Immunology course, but it may be adapted to other disciplines. Students were asked to develop and carry out a research project to examine the relationship between immune function and stress. The experiments were required to include the assessment of salivary cortisol and salivary IgA (sIgA) with enzyme immunoassays. All other aspects of the experiments were developed by student groups with appropriate guidance from the instructor. Data are presented for one group project that assessed the effect of music on cortisol and sIgA. Overall levels of sIgA and cortisol were consistent with reported values. Students found a significant decrease in cortisol over time. Additionally, there was a trend that supported the overall student hypothesis regarding the effect of stress and immune function. Compared with the same Immunology course that included an instructor-designed experiment using enzyme immunoassays for cortisol and sIgA, several assessments (e.g., final grades and comments on student evaluations) show that overall learning seemed to be much better in the course with the student-directed research project.  相似文献   
96.
This study examines how parent socioeconomic status (SES) directly and indirectly predicts children's school readiness through pathways of parental investment. Data come from direct assessments with preschool children and surveys with their primary caregivers in Ghana at the start of the 2015–2016 school year (= 2,137; Mage = 5.2 years). Results revealed SES-related gaps in all parental investment characteristics and child school readiness skills. Preschool involvement served as the primary mediating mechanism in the path from SES to most school readiness skills, though it did not predict executive function. The number of books in the household was marginally positively predictive of early literacy, whereas at-home stimulation was negatively related to motor, literacy, and numeracy skills.  相似文献   
97.
This article examines the constraints of modern temporality which are antithetical to the careful consideration that working with diverse learners requires for the development of inclusive, democratic education. We take up the conceptual construct of time to explore how it mediates systemic practices that impact policy positions of inclusion in initial teacher education and schooling. Our analysis demonstrates that temporality shapes the possibilities of inclusive practice within which a dominant agenda of compliance frames classroom complexities – both in schooling and higher education environments – into fragmented and preconceived responses to challenging situations. Education systems position educators in risk discourses concentrated on compliance and performance, in part through an emphasis that is placed on the diagnosis of learner differences and subsequent compartmentalised responses. Through schisms in modern time, we demonstrate the ways in which inclusion, like other educational demands, may be supported through a diffraction in time rather than subjugated to it.  相似文献   
98.
99.
To improve students’ outcomes and retention rates, community colleges have implemented acceleration strategies which hasten the completion of educational requirements (Edgecombe, 2011). The objective of this study was to investigate the effects of an accelerated freshmen writing course on teachers’ curricular decisions and pedagogical practices at a large urban community college. We conducted semi-structured interviews with the 11 faculty members teaching different sections of this accelerated writing course. All interviews were audiotaped, transcribed, coded, and analyzed. Our findings reveal that while instructors embrace the structural changes that come with accelerated courses and demonstrate a new appreciation for struggling students in their traditional English 101 class, they report on significant challenges in teaching due to the students’ lack of academic and personal maturity, as well as a need to lower their expectations and simplify the curriculum. This research raises questions about the unintended positive and negative effects of accelerated courses on teaching. More qualitative research is needed that focuses on the teachers’ experiences and their capacity to help students benefit from an accelerated course.  相似文献   
100.
Project Management is an important skill for business students to develop. Although project‐oriented activity is very common, the success rate for projects is poor. Many projects fail due to poor planning. This article describes a multipart class exercise used to teach elements of a project management methodology to undergraduate and graduate business students. Over the course of the eight‐part exercise, student teams iteratively develop a project plan and Gantt chart, an initial and detailed project charter, a variance analysis model, and a status report. Students are taught an iterative top‐down planning process using a technique we term the ODW (Objectives–Deliverables–Workplan) model. Students are introduced to Microsoft Project and use the tool to develop a project plan that becomes part of a more detailed Project Charter. In the final stages of the exercise, students collect results, update their plan, and produce a project status report.  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