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   17篇
  免费   2篇
教育   9篇
科学研究   8篇
信息传播   2篇
  2019年   2篇
  2018年   1篇
  2017年   2篇
  2016年   1篇
  2015年   1篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2010年   1篇
  2008年   1篇
  2005年   1篇
  2001年   1篇
  1995年   1篇
  1992年   1篇
排序方式: 共有19条查询结果,搜索用时 31 毫秒
1.
Objective: A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling oftetrapep-tide units Boc-Leu-Pro-Trp-Leu-Ome and Boc-Ile-Ala-Ala-Gly-Ome after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment.Methods: Solution phase technique was adopted for the synthesis of cyclooctapeptide--sarcodactylamide.Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz.Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-Ome and Ala-Gly-Ome.Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method.The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis.The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities.Results: Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide (DCC) as coupling agent.Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp.Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin.Conclusion: Solution phase technique employing DCC and triethylamine (TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide.N-methyl morpholine (NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.  相似文献   
2.
Since accurate decisions are required for effective management, much research has focused on information systems that support decision making. Recently, this research has engendered frameworks, such as the management support system (MSS), that are designed to provide comprehensive and integrated support for the decision making process. Few, if any, studies have empirically measured the effects of these frameworks on decision making. This article offers empirical evidence on MSS effectiveness. It overviews the decision making process, presents an MSS for supporting the process, and assesses the influences of the MSS on the process and outcomes of health care decision making. The paper also examines the implications of the analyses for information systems research and health care practice.  相似文献   
3.
We present evidence on productivity improvement experienced by the research institutes of the Chinese Academy of Sciences (CAS) after its implementation of the Knowledge Innovation Program (KIP). Using a balanced panel of data on R&D inputs and outputs of 59 research institutes in CAS, we analyze the productivity, technological and efficiency changes from 1997 to 2005. We document that the CAS research institutes have a productivity growth of 12.5% from 1998 to 2005, which can be further decomposed into 8.8% attributed to technological progress and 3.3% to efficiency improvement. Results of regional analysis show that institutes in Beijing and Shanghai, performed better than institutes in other regions during the same period.  相似文献   
4.
Students with learning disabilities often struggle with the academic demands presented in secondary mathematics curricula. To combat these students’ struggles, researchers have studied various pedagogical practices and classroom technologies for teaching standards covered in subjects such as algebra and geometry. However, as the role of computer‐ and tablet‐based technologies in education grows, some areas of study, such as the use of virtual manipulatives, lack exploration. This study sought to assess the benefits of virtual manipulatives to teach secondary students with a learning disability in mathematics how to solve multistep algebraic equations. A multiple baseline design across three participants demonstrated a functional relation between the use of a virtual manipulative balance and teaching students to acquire, maintain, and generalize the skill of solving multistep algebraic equations. Results provide new evidence demonstrating virtual manipulatives as a beneficial age‐appropriate technology to teach higher order mathematical concepts to secondary students with a learning disability.  相似文献   
5.
Transnational education is now essential to university international development strategies. As a result, tertiary educators are expected to engage with the complexities of diverse cultural contexts, different delivery modes, and mixed student cohorts to design quality learning experiences for all. To support this transition we developed a transnational curriculum design framework that synthesises knowledge about what impacts on curriculum design. This framework aims to help academic developers communicate complex educational concepts and foster international communities of practice. It guides cyclical implementation that is focused on achieving equivalent and quality educational outcomes for students regardless of their location across the globe.  相似文献   
6.
The technique of chromatography is studied to bring forth the underlying concepts such as adsorption, partition, polarity/ non-polarity of a compound. The materials required are very simple such as chalk, starch, ink, etc. Once the concepts are understood, the technique can be easily extrapolated to analyze complex biological samples as well.  相似文献   
7.
We explore how a firm’s knowledge structure characteristics and market identity—as reflected in its position in the industry value chain and market status—influence knowledge-based alliance (KBA) formation. We propose that a firm’s propensity to form KBAs is affected by the congruence (or misalignment) between its knowledge structure characteristics (i.e., knowledge depth and scope) and the role it plays in the industry, as demanded by its position in the value chain. We further argue that while a firm’s market status can amplify the positive effect of the congruence, thereby enhancing a firm’s proclivity to form KBAs, being prominent can also hurt a firm when it faces a misalignment between its knowledge structure characteristics and externally induced expectations related to its value chain position. We validate our arguments using panel data on 1051 firm-year observations for 197 firms patenting in the global fuel cell industry for the period 1999–2009. By developing a richer understanding of the relationship between a firm’s knowledge-based resources and KBA formation, we answer the call for a better understanding of how and when firms can leverage their internal knowledge configurations to improve their proclivity to form alliances.  相似文献   
8.
9.
Scholars have neglected the privatization of the Internet's backbone network, despite the obvious significance of the U.S. government turning control of a powerful new communication technology over to the private sector. This article analyzes the transition from a government-sponsored backbone network to multiple commercially owned backbone networks. The authors also analyze the implications of the privatization on the Internet's governance, competition, and performance.  相似文献   
10.
September 11, 2001 heightened the need for America to train a new generation of leaders with the ability to navigate different cultures and to succeed in the international marketplace. This paper seeks to place the community college firmly in the mix of developing such leaders through the internationalization of the community college experience. Specifically, we suggest that a focus on the 3Is— Internet (technology in the classroom); Internationalization of the curriculum (encouraging international activities in the classroom); and Interdependency (understanding of other cultures, languages, and customs)—through the illustration of case studies, will create a more educated global citizenry.  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