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   701篇
  免费   28篇
  国内免费   21篇
教育   386篇
科学研究   165篇
各国文化   11篇
体育   33篇
综合类   17篇
文化理论   7篇
信息传播   131篇
  2023年   1篇
  2022年   4篇
  2021年   19篇
  2020年   8篇
  2019年   8篇
  2018年   6篇
  2017年   14篇
  2016年   5篇
  2015年   25篇
  2014年   35篇
  2013年   60篇
  2012年   48篇
  2011年   53篇
  2010年   36篇
  2009年   52篇
  2008年   37篇
  2007年   51篇
  2006年   64篇
  2005年   42篇
  2004年   26篇
  2003年   16篇
  2002年   29篇
  2001年   22篇
  2000年   10篇
  1999年   4篇
  1998年   6篇
  1997年   7篇
  1996年   6篇
  1995年   15篇
  1994年   3篇
  1993年   3篇
  1992年   4篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1985年   2篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1978年   1篇
  1976年   2篇
  1973年   1篇
  1972年   1篇
排序方式: 共有750条查询结果,搜索用时 15 毫秒
91.
Polyethylenimine-cyclodextrin-tegafur (PEI-CyD-tegafur) conjugate was synthesized as a novel multifunctional prodrug of tegafur for co-delivery of chemotherapeutic agent tegafur and enhanced green fluorescent protein (EGFP) reporter plasmid DNA. Conjugation of tegafur to PEI-CyD via chemical linkage was characterized by 1H NMR spectrometry and ultraviolet (UV) spectrometry. PEI-CyD-tegafur was able to condense plasmid DNA into complexes of around 150 nm with positive charge at the N/P ratio of 25, in accordance with electron microscopy observation of compact and monodisperse nanoparticles. The results of in vitro experiments showed enhanced cytotoxicity and considerable transfection efficiency in B16F10 cell line. Therefore, PEI-CyD-tegafur may have great potential as a co-delivery system with anti-cancer activity and potential for gene delivery.  相似文献   
92.
Misoprostol (Cytotec) is a synthetic prostaglandin E1 analogue that was designed for the prevention and treatment of peptic ulcer associated with the use of nonsteroidal anti-inflammatory drugs. In obstetrics, misoprostol has been administered for induction of first and second trimester abortion, for induction of labor in the third trimester, and to control postpartum hemorrhage. None of these uses has been approved by the Food and Drug Administration. Nevertheless, misoprostol is widely used in the United States and throughout the world. Advantages are cited as reduced rate of cesareans, shorter time from induction to birth and, particularly in developing countries, lower cost, oral, vaginal or rectal administration, and stability without refrigeration. Disadvantages are uterine hyperstimulation and, in rare instances, uterine rupture and death. Mothers should be informed of both the risks and the possible benefits of misoprostol. Further research with large samples is necessary to determine whether the risks outweigh any possible benefits.  相似文献   
93.
The authors argue that the knowledge work metaphor is the most powerful image of schools for understanding reform. Using themes from the new management literature, such as shared decision making, collegiality, innovation, and experimentation, as additional guides for school improvement, the authors develop a case for systemic reform based on the professionalization of teaching and the integration of theory, research, and practice, Finally, transformational leadership is presented as the key to facilitating systemic reform.  相似文献   
94.
鸢尾紫色素的提取与理化性质研究   总被引:2,自引:0,他引:2  
以高原鸢尾花为原料,提取紫色色素,并对紫色色素的理化性质进行了研究。结果表明色素具有较好的稳定性,具有一定的开发利用价值。  相似文献   
95.
IN THIS COLUMN, THE AUTHOR EXAMINES RECENT RESEARCH ON TWO SEPARATE TOPICS: 1) breastfeeding; 2) postpartum length of hospital stay. Recent studies suggest long-term effects of breastfeeding that benefit both mother and infant. Benefits include a reduced risk of breast cancer in breastfeeding mothers and a reduced level of total and LDH cholesterol in adults who were breastfed as infants. Infants of mothers with maternal asthma had lower rates of asthma if the mother breastfed. In a study of women in the United States who planned to breastfeed, those mothers who breastfed exclusively and planned to breastfeed more than three months were more likely to achieve their goals than mothers who planned to combine breast and human-milk substitute feeds and to breastfeed less than three months.In a Canadian study, shortened postpartum stays led to increased re-admission to hospital for mothers with cesarean births. In contrast, in a Massachusetts study, shortened postpartum stays did not lead to an increase in infant visits for urgent care. However, the Massachusetts study did not reflect a decrease in maternity-related costs associated with shortened length of postpartum stay.  相似文献   
96.
We report that a 63-year-old Chinese female had acute myeloblastic leukemia (AML) in which trisomy 21 (+21) was found as the sole acquired karyotypic abnormality. The blasts were positive for myeloperoxidase, and the immunophenotype was positive for cluster of differentiation 19 (CD19), CD33, CD34, and human leukocyte antigens (HLA)-DR. The chromosomal analysis of bone marrow showed 47,XX,+21[2]/46,XX[18]. Fluorescent in situ hybridization (FISH) showed that three copies of AML1 were situated in separate chromosomes, and that t(8;21) was negative. The patient did not have any features of Down syndrome. A diagnosis of CD19-positive AML-M5 was established with trisomy 21 as a sole acquired karyotypic abnormality. The patient did not respond well to chemotherapy and died three months after the diagnosis. This is the first reported case of CD19-positive AML with trisomy 21 as the sole cytogenetic abnormality. The possible prognostic significance of the finding in AML with +21 as the sole acquired karyotypic abnormality was discussed.  相似文献   
97.
Information Commons是一种全新的信息服务模式,文章深入探讨了图书馆信息服务由传统的文献保障向学科化知识化特色化服务转移过程要充分运用IC服务理念,坚持学科特色、读者需求、空间结合、技术支持以及规范管理的原则,建设具有生物医学特色的专题阅览室。  相似文献   
98.
99.
This article describes an interdisciplinary continuing education approach for health professionals in a rural remote area implemented by the Northern Educational Centre for Aging and Health (NECAH) at Lakehead University in Thunder Bay, Ontario, Canada. The article discusses issues of rural health care practice and the implications for practitioners’ educational needs. The key components involved in delivering interdisciplinary education and teamwork training are reviewed, followed by a discussion of the relevance of an interdisciplinary participatory approach for rural practitioners given their practice context and work style. Using NECAH's experience in planning and delivering a 5‐day interdisciplinary education program in palliative care as a case example, it is argued that simultanous attention to these issues in the design and delivery of continuing professional education for rural professionals contributes to a relevant educational experience in the short‐term and an increased interdisciplinary collaboration in the long‐term. The article suggests that NECAH's interdisciplinary participatory approach is a significant model for the continuing education of health professionals in rural remote areas.  相似文献   
100.
小鹅瘟在国内已广泛流行,雏鹅的预防和治疗以鹅抗小鹅瘟血清较为理想,但若用山羊抗小鹅瘟血清,则可获得大量的血清及长时间采血且降低成本,经笔者研制的山羊抗血清具琼扩试验效价达1:16;保护试验保护率达80—100%小范围区域试验保护率达95%。  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