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   9003篇
  免费   578篇
  国内免费   69篇
耳鼻咽喉   40篇
儿科学   205篇
妇产科学   103篇
基础医学   949篇
口腔科学   149篇
临床医学   951篇
内科学   2295篇
皮肤病学   158篇
神经病学   487篇
特种医学   212篇
外国民族医学   2篇
外科学   1638篇
综合类   235篇
现状与发展   1篇
一般理论   5篇
预防医学   539篇
眼科学   227篇
药学   823篇
中国医学   156篇
肿瘤学   475篇
  2024年   14篇
  2023年   146篇
  2022年   524篇
  2021年   678篇
  2020年   398篇
  2019年   487篇
  2018年   481篇
  2017年   312篇
  2016年   329篇
  2015年   358篇
  2014年   438篇
  2013年   525篇
  2012年   799篇
  2011年   736篇
  2010年   360篇
  2009年   333篇
  2008年   498篇
  2007年   458篇
  2006年   389篇
  2005年   359篇
  2004年   279篇
  2003年   262篇
  2002年   126篇
  2001年   51篇
  2000年   47篇
  1999年   26篇
  1998年   23篇
  1997年   11篇
  1996年   14篇
  1995年   6篇
  1994年   7篇
  1993年   11篇
  1992年   15篇
  1991年   10篇
  1990年   8篇
  1989年   6篇
  1988年   20篇
  1985年   6篇
  1984年   9篇
  1983年   5篇
  1982年   6篇
  1981年   14篇
  1978年   8篇
  1977年   6篇
  1976年   4篇
  1975年   5篇
  1972年   7篇
  1969年   9篇
  1968年   5篇
  1967年   4篇
排序方式: 共有9650条查询结果,搜索用时 15 毫秒
131.
OBJECTIVE: To evaluate the dose-related benefit of angiotensin-converting enzyme (ACE) inhibitor therapy among older adults with heart failure and to evaluate whether low-dose ACE inhibitor therapy is better than none. DESIGN: Observational cohort study. SETTING: Community-dwelling older adults in Ontario, Canada. PATIENTS/PARTICIPANTS: We identified 16539 adults 66 years or older who survived 45 days following their first heart failure hospitalization discharge. MEASUREMENT AND MAIN RESULTS: Multivariate techniques including propensity scores were used to study the association between the dose of ACE inhibitor therapy dispensed and 3 outcomes: survival, survival or heart failure rehospitalization, and survival or all-cause hospitalization at 1 year of follow-up. Logistic regression models explored the association between initial dose dispensed and subsequent dose reduction or drug cessation. Overall, 10793 (65.3%) of patients were dispensed ACE inhibitor therapy, with more than a third (3935; 36.5%) initiated on low-dose therapy. Relative to dispensing of low-dose ACE inhibitor therapy, nonuse was associated with increased mortality (hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.02 to 1.22). Dispensing medium-dose therapy provided a benefit similar to low-dose (HR, 0.94; CI, 0.86 to 1.03) and dispensing of high-dose therapy was associated with improved survival benefit (HR, 0.76; CI, 0.68 to 0.85). Relative to dispensing of low-dose ACE inhibitor therapy, dispensing high-dose conferred a benefit (HR, 0.87; CI, 0.80 to 0.95) on the composite outcome of 1-year mortality or heart failure hospitalization and the composite outcome of 1-year mortality or all-cause hospitalization (HR, 0.87; CI, 0.81 to 0.93). Relative to those dispensed low-dose ACE inhibitor therapy, those initially dispensed high-dose therapy were twice as likely to have their subsequent dose reduced or the therapy discontinued (odds ratio, 2.36; CI, 2.07 to 2.69). CONCLUSION: Our findings suggest that when possible, older adults should be titrated to the higher doses of ACE inhibitor therapy evaluated in clinical trials. If older adults cannot tolerate higher doses, then low-dose ACE inhibitor therapy is superior to none. High-dose ACE inhibitor therapy is not as well tolerated as lower doses.  相似文献   
132.
133.
134.
135.
136.
137.
138.
Context: Human/animal shaving biology.

Objective: To assess the effect of shaving on percutaneous penetration and skin function.

Methods: We screened 500+publications in Pub Med, Scopus, Cochrane Library and pertinent journals out of which only 17 were deemed relevant. Terms for searches included shaving and skin, percutaneous penetration and shaving, skin absorption and shaving, absorption of dyes and shaving, skin penetration, effects of shaving and absorption, shave and dyes, axillary shaving and stratum corneum, shaving and breast cancer, shaving and infections, etc.

Result: Shaving appears to have an exaggerated effect on percutaneous absorption; however, some studies do not support this evidence.

Conclusion: Shaving enhances percutaneous penetration of some chemicals; however this effect is species and chemical specific. Further investigations of chemicals of varying physio-chemical properties are mandated before a generalized theory can be promulgated.  相似文献   

139.
140.

Background

The present work objective was to prepare and to observe the effect of ethylene glycol dimethacrylate on swelling and on drug release behavior of pH-sensitive acrylic acid–polyvinyl alcohol hydrogel.

Methods

In the present work, pH sensitive acrylic acid–polyvinyl alcohol hydrogels have been prepared by free radical polymerization technique in the presence of benzoyl peroxide as an initiator. Different crosslinker contents were used to observe its effect on swelling and on drug release. Dynamic and equilibrium swelling studies of prepared hydrogels were investigated in USP phosphate buffer solutions of pH 1.2, 5.5, 6.5 and 7.5 with constant ionic strengths. Hydrogels were evaluated for polymer volume fraction, solvent interaction parameter, molecular weight between crosslinks, number of links per polymer chain, diffusion coefficient, sol–gel fraction and porosity. To demonstrate the release pattern of the drug, zero-order, first-order, higuchi and korsmeyer-peppas models were applied. Quality and consistency of hydrogels was examined by FTIR and surface morphology of hydrogels was examined by SEM.

Results

Decrease in swelling and in drug release was seen by increasing content of ethylene glycol dimethacrylate. A remarkable high swelling was observed at high pH indicating the potential of this hydrogel for delivery of drugs to intestine. By increasing the concentration of ethylene glycol dimethacrylate, porosity decreased. Order of release was observed first order in all cases and the mechanism was non–fickian diffusion. FTIR confirmed the formation of network. SEM results showed the incorporation of drug.

Conclusion

The prepared hydrogels can be suitably used for targeted drug delivery to the intestine.  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