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   265篇
  免费   8篇
  国内免费   4篇
儿科学   10篇
妇产科学   1篇
基础医学   23篇
口腔科学   4篇
临床医学   15篇
内科学   37篇
皮肤病学   11篇
神经病学   10篇
特种医学   51篇
外科学   37篇
综合类   12篇
预防医学   14篇
药学   33篇
肿瘤学   19篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2016年   2篇
  2015年   6篇
  2014年   6篇
  2013年   6篇
  2012年   6篇
  2011年   3篇
  2010年   13篇
  2009年   16篇
  2008年   7篇
  2007年   8篇
  2006年   13篇
  2005年   5篇
  2004年   15篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   23篇
  1997年   17篇
  1996年   11篇
  1995年   8篇
  1994年   8篇
  1993年   10篇
  1992年   6篇
  1991年   5篇
  1990年   11篇
  1989年   12篇
  1988年   7篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   4篇
  1975年   4篇
  1966年   1篇
排序方式: 共有277条查询结果,搜索用时 15 毫秒
21.
22.
新缩瞳剂包公藤甲素人工合成研究   总被引:11,自引:0,他引:11  
包公藤甲素是从包公藤(Erycibe obtusifolia Benth.)茎中提得的一个新莨菪烷生物碱,具有强烈的缩瞳作用,临床用于治疗青光眼。本文报道用合成的6β-乙酰氧基托品酮为原料,经卤代、水解、还原和N-去甲基化等反应合成包甲素(8)。经光谱测定证实8与天然包甲素的结构完全一致。合成品系外消旋体,其作用机理与天然品相同,而强度则减半。  相似文献   
23.
In 1997, the United States Pharmacopeia (USP) established an Ad Hoc Outcomes/Cost Effectiveness Advisory Panel to consider the development of specifications for compiling, indexing, and evaluating outcomes research/cost-effectiveness literature on a disease-specific basis. Such a resource could be used to support pharmaceutical therapy choice decision making by a variety of potential users. The USP had developed a protype health outcomes and pharmacoeconomic annotated registry of the literature on the disease state, congestive heart failure. Other organizations have established and are marketing pharmacoeconomic and health outcome literature registries, with two examples being the HEED database (OHE-IFPMA Database Ltd.) and the University of York NHS Centre for Reviews and Dissemination (DARE).
OBJECTIVE: To share experiences and to identify the needs of decision makers for outcome/pharmacoeconomic information and to discuss whether they are being met by currently available literature sources. Decision makers include health care practitioners, managed care organizations, third party payers, industry and governments.
WORKSHOP FORMAT: The USP congestive heart failure protype literature registry will be described and compared to currently available pharmacoeconomic/outcome databases. Participants will share their assessment of the currently available abstracting service/databases and determine if there is a role for further developments.
DESIRED OUTCOME: To determine if there is a need for a collaborative approach among interested parties to make relevant health outcome/pharmacoeconomic information more accessible to the drug therapy decision makers in a format that is "user friendly."  相似文献   
24.
25.
26.
裴月湖  李铣  朱廷儒 《药学学报》1989,24(6):413-421
合成了14个新化合物,其中有12个是(S)-(+)-α-甲基丁酰基间苯三酚类化合物。通过对新化合物旋光资料的研究和分析,找到了它们绝对构型与旋光方向的关系。该规律在测定光学活性的α-甲基丁酰基间苯三酚类化合物的绝对构型和开发研究该类药物上,均具有一定的实际应用价值。  相似文献   
27.
从秋季采收的菊科植物大丁草Gerbera anandria(L.)Sch Bip.全草中共分出十三种成分。本文报道其中三个新化合物的结构鉴定.它们分别是3,8-dihydroxy-4-methoxy-coumarin(ⅪⅩ),3,8-dihydroxy-4-methoxy-2-oxo-2 H-1-benzopyran-5-carboxylic acid(ⅩⅦ),和5,8-dihydroxy-7-(4-hydroxy-5-methyl-coumarin-3-)-coumarin(ⅩⅪ)。  相似文献   
28.
Total radical trapping antioxidant potential (TRAP) and exercise   总被引:1,自引:0,他引:1  
The relationship between physical activity, physical fitness and total radical trapping antioxidant potential (TRAP) was examined in the Northern Ireland Health and Activity Survey. This was a cross-sectional population study (n = 1600) using a two-stage probability sample of the population. TRAP was calculated using the sum of the individual serum antioxidant concentrations (urate, protein thiols, ascorbate, alpha tocopherol and bilirubin) multiplied by their respective stoichiometric values. Physical fitness was determined by estimation of VO2max by extrapolation from submaximal oxygen uptake, and physical activity was recorded by computer-assisted interview. Mean serum TRAP concentrations were significantly higher in males (653 +/- 8.2 mumol/l, mean +/- SEM) compared to females (564 +/- 8.0 mumol/l) (p < 0.0001). Both male and female smokers had significantly lower TRAP values than non-smokers (males p < 0.0001, females p = 0.02). In females, there was a positive relationship of TRAP with age (p < 0.001) and body mass index (p < 0.001) but a negative relationship with physical fitness (p < 0.05). The known beneficial effects of exercise and activity do not appear to be directly mediated through increased antioxidant status.   相似文献   
29.
John George Adami (1862-1926) qualified in medicine at Manchester and in 1892 was appointed professor of pathology at McGill University. At the invitation of the Royal College of Physicians (in London) he delivered the Croonian Lectures in 1917. He chose the title 'Adaptation and disease; the contribution of medical research to the study of evolution'. Adami believed that medical work had brought to light important facts about heredity that had not been communicated adequately to biological scientists. He used the lectures to describe this work, placing particular emphasis on his contention that acquired characters are inherited. At this time the medical audience at Adami's lectures would have been generally sympathetic to the idea that acquired characters can be inherited, though many leading British biologists were not sympathetic. Adami hoped that a concise review of the medical findings would persuade the biologists to his point of view or at least would be the starting point for a serious discussion of his evidence. However, the biologists were not persuaded and, although there were acrimonious personal exchanges, there was no scientific debate.  相似文献   
30.

Objective

To develop and evaluate a text mining system for extracting key clinical features from vaccine adverse event reporting system (VAERS) narratives to aid in the automated review of adverse event reports.

Design

Based upon clinical significance to VAERS reviewing physicians, we defined the primary (diagnosis and cause of death) and secondary features (eg, symptoms) for extraction. We built a novel vaccine adverse event text mining (VaeTM) system based on a semantic text mining strategy. The performance of VaeTM was evaluated using a total of 300 VAERS reports in three sequential evaluations of 100 reports each. Moreover, we evaluated the VaeTM contribution to case classification; an information retrieval-based approach was used for the identification of anaphylaxis cases in a set of reports and was compared with two other methods: a dedicated text classifier and an online tool.

Measurements

The performance metrics of VaeTM were text mining metrics: recall, precision and F-measure. We also conducted a qualitative difference analysis and calculated sensitivity and specificity for classification of anaphylaxis cases based on the above three approaches.

Results

VaeTM performed best in extracting diagnosis, second level diagnosis, drug, vaccine, and lot number features (lenient F-measure in the third evaluation: 0.897, 0.817, 0.858, 0.874, and 0.914, respectively). In terms of case classification, high sensitivity was achieved (83.1%); this was equal and better compared to the text classifier (83.1%) and the online tool (40.7%), respectively.

Conclusion

Our VaeTM implementation of a semantic text mining strategy shows promise in providing accurate and efficient extraction of key features from VAERS narratives.  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