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   162篇
  免费   1篇
教育   91篇
科学研究   44篇
各国文化   4篇
体育   8篇
文化理论   4篇
信息传播   12篇
  2023年   1篇
  2022年   6篇
  2021年   7篇
  2020年   7篇
  2019年   10篇
  2018年   16篇
  2017年   10篇
  2016年   7篇
  2015年   4篇
  2014年   15篇
  2013年   21篇
  2012年   5篇
  2011年   14篇
  2010年   5篇
  2009年   6篇
  2008年   5篇
  2007年   3篇
  2006年   3篇
  2005年   2篇
  2000年   1篇
  1997年   4篇
  1995年   1篇
  1992年   1篇
  1991年   1篇
  1989年   2篇
  1988年   1篇
  1983年   2篇
  1981年   2篇
  1979年   1篇
排序方式: 共有163条查询结果,搜索用时 15 毫秒
71.
72.
本研究试图论证基于平衡的风险分担原则在解决公私合作伙伴关系(PPP)项目风险分担问题上是最有效的,并提出实施该原则的建议.为了满足公共部门和私人部门的不同利益和目标,PPP项目应建立一个可行及有利可图的风险分担机制.一个有效的风险分担机制既是项目文件准备的重要部分,也是PPP合同成功不可或缺的一部分.风险分担可用风险矩...  相似文献   
73.
To examine the possible involvement of human B cell leukemia/lymphoma 2 (Bcl-2), CD4+ cells, hepatocyte growth factor (HGF), and metalloproteinase-9 (MMP-9), as biomarkers in early diagnosis of hepatocellular carcinoma (HCC), activities of these biomarkers in serum were demonstrated by the method of Enzyme Linked Immunosorbant Assay. Two groups of subjects (60 for each), were examined in this study; healthy controls and patients with HCC. The present results declare that, significant decrease in Bcl-2 (p ≤ 0.0001), and CD 4+ (p ≤ 0.001), while significant increase in HGF and MMP-9 (p ≤ 0.05). These findings imply an influence of these biomarkers by the existence of hepatic carcinoma that might reflect the progression of disease and a distinction between the pathological mechanisms involved in hepatic carcinoma. Since, the serum MMP-9 activity was significantly varied between each stage of HCC. An individual profile of the present investigated parameters was detected that might serve as an easy accessing serum marker to monitor the progression of hepatic cell disorders.  相似文献   
74.
The purpose of this mixed‐methods study was to explore special education teachers’ attitudes towards using technology in inclusive classrooms in Oman. The sample consisted of 428 special education teachers working in Omani public schools (250 teachers of students with learning disabilities (LD), 90 teachers of students with intellectual disability and 88 teachers of students with hearing impairment). Participants responded to the attitudes towards computers questionnaire. For the qualitative section of this study, three semi‐structured group interviews were conducted with a group of special education teachers: 15 teachers of students with hearing impairment, 15 teachers of students with intellectual disabilities and 15 teachers of students with LD). Also, the teachers responded to a survey of educational technology which encompassed seven questions about computer technology. Results of the study indicated that the special education teachers’ attitudes towards using computers were generally positive. The most notable positive attitudes were in the following subscales: special education considerations, staff development considerations, computers use in society, and computers and quality of instruction issues. The analysis of variance results showed that experience and type of disability did not have a significant effect on teachers’ attitudes towards technology.  相似文献   
75.
In urbanized areas, incorporating residents’ concerns and priorities into the stormwater management debate has focused on adults rather than youth. This study used Photovoice, a tool that includes photographs taken by youth, to uncover youth concerns and perceptions about their local watersheds. This study consisted of a comparative study of two watersheds. Twenty students produced 468 photographs. Although both groups of students shared common themes regarding stormwater and pollution, these themes differed in level of concerns over local environmental issues, sentiments with particular features in their local watersheds, and concerns about local watersheds. From a methodological perspective, Photovoice provided a way of capturing youth perspectives and to identify important features and issues in their respective local watersheds.  相似文献   
76.
Numerous studies are demonstrating that engaging undergraduate students in original research can improve their achievement in the science, technology, engineering, and mathematics (STEM) fields and increase the likelihood that some of them will decide to pursue careers in these disciplines. Associated with this increased prominence of research in the undergraduate curriculum are greater expectations from funders, colleges, and universities that faculty mentors will help those students, along with their graduate students and postdoctoral fellows, develop an understanding and sense of personal and collective obligation for responsible conduct of science (RCS). This Feature describes an ongoing National Research Council (NRC) project and a recent report about educating faculty members in culturally diverse settings (Middle East/North Africa and Asia) to employ active-learning strategies to engage their students and colleagues deeply in issues related to RCS. The NRC report describes the first phase of this project, which took place in Aqaba and Amman, Jordan, in September 2012 and April 2013, respectively. Here we highlight the findings from that report and our subsequent experience with a similar interactive institute in Kuala Lumpur, Malaysia. Our work provides insights and perspectives for faculty members in the United States as they engage undergraduate and graduate students, as well as postdoctoral fellows, to help them better understand the intricacies of and connections among various components of RCS. Further, our experiences can provide insights for those who may wish to establish “train-the-trainer” programs at their home institutions.  相似文献   
77.
Over the last three decades, research in Information Retrieval (IR) shows performance improvement when many sources of evidence are combined to produce a ranking of documents. Most current approaches assess document relevance by computing a single score which aggregates values of some attributes or criteria. They use analytic aggregation operators which either lead to a loss of valuable information, e.g., the min or lexicographic operators, or allow very bad scores on some criteria to be compensated with good ones, e.g., the weighted sum operator. Moreover, all these approaches do not handle imprecision of criterion scores. In this paper, we propose a multiple criteria framework using a new aggregation mechanism based on decision rules identifying positive and negative reasons for judging whether a document should get a better ranking than another. The resulting procedure also handles imprecision in criteria design. Experimental results are reported showing that the suggested method performs better than standard aggregation operators.  相似文献   
78.
Knowledge is the currency of the current economy and a vital resource for sustaining organisational performance in today’s knowledge-based intensively competitive business environment. To avoid the detrimental consequences of knowledge loss, managers are urged to identify where knowledge stocks exist and how knowledge flows within their organisations by identifying knowledge holders among their employees. Although some studies have attempted to use different methods to measure knowledge at the organisational level, very few have addressed the individual knowledge holder. Moving from a critical literature review of the existing knowledge measurement approaches, this paper proposes a novel framework that enables organisations to measure individual knowledge in the business context using a set of metrics, which are subsequently validated via a series of in-depth interviews with senior managers. A summary of the managers’ views on individual knowledge measurement is presented, and reflections on the industry application of the proposed framework and recommendations for its improvement are also discussed.  相似文献   
79.
A metabolomic study for determination of certain urinary metabolomes, 1-methyladenosine (1-MA), 1-methylguanosine (1-MG), and 8-hydroxy-2′ deoxyguanosine (8-OHdG) in urine specimens of breast cancer patients. The accuracy of these metabolites and their combined score with cancer antigen 15-3 (CA15-3) was developed to improve the early detection of breast cancer. This study recruited 52 healthy individuals, 47 benign breast tumors, and 167 malignant breast tumor patients. Urine samples were handled to adjust the creatinine concentrations to 8 mg/dL (0.7 mmol/L) and analyzed using GC–MS to detect and quantify the selected urinary metabolomes in urine samples of all participants. The accuracy of individual urinary metabolomes and their combination with CA15-3 were evaluated using multivariate statistical analysis. The cutoff value of CA15-3 was 32.5 U/mL. Cutoff values of 1-MA, 1-MG, and 8-OHdG were 2.19, 2.1, and 7.3 µmol/mmol creatinine, respectively. The concentrations of 1-MA, 1-MG, and 8-OHdG were significantly higher in breast cancer patients, especially in the early-stage. The combination of three urinary metabolomes with CA15-3 improves the diagnostic sensitivity of breast cancer. For the combined score, the area under the curve (AUC) value of combined score ranged from 0.820 to 0.950, with high accuracy, ranged from 77.0 to 95.5%. The most significant AUC (0.973), sensitivity (90.1%), selectivity (94.0%) was recorded at comparing the healthy control with the early-stage of malignant breast cancer. In conclusion, the combination of three urinary metabolomes with serum CA15-3 improves the diagnostic sensitivity of breast cancer.  相似文献   
80.
This paper deals with the problem of model reference control for linear parameter varying (LPV) systems. The LPV systems under consideration depend on a set of parameters that are bounded and available online. The main contribution of this paper is to design an LPV model reference control scheme for LPV systems whose state-space matrices depend affinely on a set of time-varying parameters that are bounded and available online. The design problem is divided into two subproblems: the design of the coefficient matrices of the controller and the design of the gain of the state feedback controller for LPV systems. The singular value decomposition is used to obtain the coefficient matrices, while the linear matrix inequality methodology is used to obtain the parameter-dependent state feedback gain of the control scheme. A simple numerical example is used to illustrate the proposed design and a coupled-tank process example is used to demonstrate the usefulness and practicality of the proposed design. Simulation and experimental results indicate that the proposed scheme works well.  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