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   755篇
  免费   66篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   42篇
妇产科学   4篇
基础医学   66篇
口腔科学   40篇
临床医学   71篇
内科学   162篇
皮肤病学   20篇
神经病学   31篇
特种医学   132篇
外科学   53篇
综合类   77篇
一般理论   1篇
预防医学   51篇
药学   45篇
  1篇
中国医学   1篇
肿瘤学   30篇
  2022年   3篇
  2021年   8篇
  2020年   4篇
  2019年   7篇
  2018年   21篇
  2017年   10篇
  2016年   15篇
  2015年   19篇
  2014年   21篇
  2013年   25篇
  2012年   19篇
  2011年   19篇
  2010年   27篇
  2009年   31篇
  2008年   21篇
  2007年   23篇
  2006年   40篇
  2005年   14篇
  2004年   17篇
  2003年   20篇
  2002年   15篇
  2001年   13篇
  2000年   8篇
  1999年   7篇
  1998年   30篇
  1997年   50篇
  1996年   45篇
  1995年   33篇
  1994年   33篇
  1993年   36篇
  1992年   19篇
  1991年   8篇
  1990年   13篇
  1989年   13篇
  1988年   17篇
  1987年   9篇
  1986年   7篇
  1985年   8篇
  1984年   9篇
  1983年   11篇
  1982年   16篇
  1981年   14篇
  1980年   8篇
  1979年   5篇
  1978年   4篇
  1977年   6篇
  1976年   15篇
  1975年   9篇
  1973年   1篇
  1971年   1篇
排序方式: 共有828条查询结果,搜索用时 0 毫秒
21.
22.
23.
Context: Available artemisinin-combination therapies (ACTs) are expensive. Various traditional herbal remedies for malaria involve plants, proven scientifically to have antiplasmodial effects, e.g., Azadirachta indica A. Juss. (Meliaceae).

Objective: Combination of an artemisinin-based compound and a medicinal herb extract will provide an indigenous alternative/herb-based ACT.

Materials and methods: The in vivo schizontocidal activity of the crude aqueous extract of 100, 500, and 1000?mg/kg of A. indica fresh leaves (NCE) and 6, 15, and 20?mg/kg of artesunic acid were determined, alone and in combination, while keeping the dose of artesunic acid constant at 15?mg/kg, using the Peter’s 4-day suppressive test and Swiss albino mice. The ED50 was calculated from the dose-response relationships. Percentage survival and cure were also determined.

Results: The average yield of two extractions of NCE was 8.33?±?1.67%. Combination of 1000?mg/kg of NCE and 15?mg/kg of artesunic acid, produced a significant reduction of parasitemia (96.87%), compared to 20?mg/kg of artesunic acid alone (68.14%). The combination had an ED50 of 0.58?mg/kg while that of artesunic acid alone was 8.814?mg/kg. The combinations of NCE with artesunic acid produced a cure, although the artesunic acid did not produce a cure in 30?d.

Discussion: NCE increased the activity of artesunic acid in terms of reduction in parasitemia, and increased survival time and cure rate.

Conclusion: The combination of an artemisinin and aqueous extract of neem leaf is possible, providing a potentiated reduction of parasitemia, and increased cure rate.  相似文献   
24.
25.
Cytogenetic and histologic correlations in malignant lymphoma   总被引:9,自引:0,他引:9  
Although a number of studies have indicated correlations between histologic subtypes of tumors and certain nonrandom chromosome changes, cytogenetic studies of lymphoma are in an early stage compared to those of leukemia. No comprehensive analysis of available data has so far been attempted in the literature either. Here we present an analysis of chromosome changes and their correlation with subtypes of lymphoma studied by conventional histology and cell surface markers, as observed in two sets of data: a group of 65 karyotypically abnormal tumors sequentially ascertained and studied by us during the period January 1, 1984 to April 30, 1985, and a larger data set derived by combining our data with those from two published series from the University of Minnesota that are comparable to our data. These combined data, which comprise the largest data set on the cytogenetics of lymphomas assembled so far, enabled a comprehensive analysis of correlation between chromosome change and tumor histology and the patterns of chromosome instability in these tumors. We found several significant associations, some previously described and others now recognized, between nonrandom chromosome gains, breaks, translocations, and deletions and histologic subtypes of tumors that characterize lymphomas. The data indicate that finding of chromosome breaks at certain sites (eg, 8q24, 14q32, 18q21) is of diagnostic value in dealing with cases of unusual lymphoma. Furthermore, nonrandom chromosome breakage exhibited three distinct patterns that reflected three levels of etiologically relevant genetic change.  相似文献   
26.
27.
Immunoglobulin V regions and the B cell   总被引:7,自引:2,他引:7  
Stewart  AK; Schwartz  RS 《Blood》1994,83(7):1717-1730
  相似文献   
28.
Quito  FL; Beh  J; Bashayan  O; Basilico  C; Basch  RS 《Blood》1996,87(4):1282-1291
Fibroblast growth factor-4 (FGF-4), a highly mitogenic protein encoded by the k-fgf/hst oncogene, stimulates the growth of a variety of cells of mesenchymal and neuroectodermal origin. Addition of FGF-4 to human long-term bone marrow cultures increased both the cell density of the stromal layer and the number of hematopoietic colony forming cells in the cultures in a dose-dependent manner. Hematopoiesis in the stromal layer persisted for up to 8 months. Erythropoiesis was maintained for up to 4 weeks, but granulocytes were the predominant nonadherent cell type. Cultures treated with FGF had increased numbers of monocytes compared with control cultures and some CD14+, CD45+ monocytes could still be detected after 8 months of continuous culture. The addition of the growth factor increased the rate of growth of the stromal layer and appeared to delay its senescence. Subcultures made in the presence of FGF-4 had up to 10-fold increases in plating efficiency and grew as relatively uniform monolayers. These subcultures retained the capacity to support hematopoiesis for several months, while untreated subcultures, made without FGF-4, grew erratically and generally lost the capacity to support hematopoiesis within 4 to 6 weeks. The improved growth after subculture greatly enhanced the reliability of limit- dilution assays of multipotential hematopoietic stem cells that use stromal cell monolayers. The primary effect of FGF-4 appeared to be on the stromal cells of the long-term bone marrow cultures, but a direct effect on hematopoietic progenitors could not be ruled out.  相似文献   
29.

Background

In Nigeria, one of the major challenges associated with evidence-to-policy link in the control of infectious diseases of poverty (IDP), is deficient information literacy knowledge and skill among policymakers. There is need for policymakers to acquire the skill to discover relevant information, accurately evaluate retrieved information and to apply it correctly.

Objectives

To use information literacy tool of International Network for Availability of Scientific Publications (INASP) to enhance policymakers'' knowledge and skill for policymaking on control of IDP in Nigeria.

Methods

Modified "before and after" intervention study design was used in which outcomes were measured on target participants both before the intervention is implemented and after. This study was conducted in Ebonyi State, south-eastern Nigeria and participants were career health policy makers. A two-day health-policy information literacy training workshop was organized to enhance participants" information literacy capacity. Topics covered included: introduction to information literacy; defining information problem; searching for information online; evaluating information; science information; knowledge sharing interviews; and training skills.

Results

A total of 52 policymakers attended the workshop. The pre-workshop mean rating (MNR) of knowledge and capacity for information literacy ranged from 2.15-2.97, while the post-workshop MNR ranged from 3.34-3.64 on 4-point scale. The percentage increase in MNR of knowledge and capacity at the end of the workshop ranged from 22.6%-55.3%.

Conclusion

The results of this study suggest that through information literacy training workshop policy makers can acquire the knowledge and skill to identify, capture and share the right kind of information in the right contexts to influence relevant action or a policy decision.  相似文献   
30.
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