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   7736篇
  免费   458篇
  国内免费   46篇
耳鼻咽喉   56篇
儿科学   210篇
妇产科学   172篇
基础医学   1164篇
口腔科学   200篇
临床医学   732篇
内科学   1469篇
皮肤病学   184篇
神经病学   775篇
特种医学   307篇
外科学   1021篇
综合类   27篇
一般理论   1篇
预防医学   613篇
眼科学   169篇
药学   634篇
中国医学   8篇
肿瘤学   498篇
  2023年   86篇
  2022年   145篇
  2021年   276篇
  2020年   180篇
  2019年   225篇
  2018年   254篇
  2017年   178篇
  2016年   209篇
  2015年   261篇
  2014年   315篇
  2013年   406篇
  2012年   553篇
  2011年   554篇
  2010年   309篇
  2009年   261篇
  2008年   440篇
  2007年   460篇
  2006年   368篇
  2005年   382篇
  2004年   324篇
  2003年   244篇
  2002年   249篇
  2001年   111篇
  2000年   112篇
  1999年   115篇
  1998年   54篇
  1997年   52篇
  1996年   40篇
  1995年   30篇
  1994年   40篇
  1993年   20篇
  1992年   61篇
  1991年   60篇
  1990年   53篇
  1989年   57篇
  1988年   49篇
  1987年   43篇
  1986年   40篇
  1985年   46篇
  1984年   34篇
  1983年   25篇
  1979年   31篇
  1977年   23篇
  1975年   30篇
  1974年   28篇
  1973年   29篇
  1972年   26篇
  1971年   33篇
  1969年   20篇
  1968年   19篇
排序方式: 共有8240条查询结果,搜索用时 15 毫秒
1.
2.
3.

Introduction

Invasive meningococcal disease (IMD) is a severe disease mainly affecting infants and young children. The most common serogroup causing IMD in Germany is the serogroup type B Neisseria meningitidis (MenB). The aim of the present study is to estimate the economic burden of MenB-related IMD in Germany.

Method

A bottom-up, model-based costing approach has been used to calculate the diagnose- and age-specific yearly lifetime costs of a hypothetical cohort of MenB-related IMD cases. Direct costs contain the treatment cost for the acute phase of the disease, long-term sequelae, costs for rehabilitation, and public health response. Indirect costs are calculated for the human-capital approach and the friction-cost approach considering productivity losses of patients or parents for the acute phase and long-term sequelae. Publicly available databases from the Federal Statistical Office, the SOEP panel data set, literature, and expert opinion were used as data sources. All future costs beyond the reference year of 2015 were discounted at 3%.

Results

The total costs for the hypothetical cohort (343 patients) from a societal perspective are €19.6 million (€57,100/IMD case) using the friction-cost approach and €58.8 million (€171,000/IMD case) using the human-capital approach. Direct costs amount to €18.6 million or €54,300 €/case. Sequelae are responsible for 81% of the direct costs/case.

Discussion

The elevated costs/MenB-related IMD case reflect the severity of the disease. The total costs are sensitive to the productivity-loss estimation approach applied. MenB is an uncommon but severe disease; The costs/case reflect the severity of the disease and is within the same magnitude as for human papilloma virus infections. The available literature on sequelae is due to the uncommonness limited and heterogeneous.  相似文献   
4.
5.
A review of the literature was performed to explore the association between prenatal education and rates of primary cesarean birth for women at low risk for cesarean birth. Most women who are nulliparous with a singleton fetus of term gestational age and in the vertex position are considered to be at low risk and favorable for a vaginal birth, yet the cesarean birth rate for women at low risk was 25.6% in 2019. It has been suggested that the rise in the cesarean birth rate among low-risk women may not be due to medical indications but, rather, to nonmedical factors, such as a provider’s or woman’s preference or lack of prenatal education. Evidence from this literature review supports the premise that prenatal education classes should be routinely incorporated into maternity care in an effort to reduce cesarean birth rates for the low-risk population.  相似文献   
6.
7.
Background: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension.

Methods: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested.

Results: Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA.  相似文献   

8.
This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.  相似文献   
9.
Based on a standardized in-vitro method for quantifying the activity of prostaglandin-synthetase by means of coupling malondialdehyde with 2-thiobarbituric acid the possibility of using this method also as ex-vivo technique is described. By this, more favourable prerequisites to pharmacological valuation of the effects of potential antiinflammatory substances exists compared to the application of in-vitro results, only.  相似文献   
10.
OBJECTIVE: Accelerated re-endothelialisation may inhibit the development of restenosis. Basic Fibroblast Growth Factor (bFGF) plays a key role for early proliferative activity in the artery following injury. Therefore, this study was devised to examine the effect of photodynamic therapy (PDT) on post-injury re-endothelialisation in vivo, and bFGF-mRNA expression in endothelial cells (EC) in vitro. MATERIALS AND METHODS: Rat carotid arteries were balloon-injured prior to PDT. Arteries were analysed after 1, 3, 5, 14 and 30 days. Morphometric measurements were undertaken following injection of 0.5% Evans Blue which stains non-endothelialised surfaces only. To identify EC, immunohistochemistry (CD-31) was performed. Proliferation was assessed by fluorescence cell counting. PCR quantification of bFGF-mRNA expression and proliferation were assessed in bovine aortic EC which were plated on isolated, PDT-treated EC-derived extracellular matrix at (12), 24, 48 (72 h). RESULTS: Three days following PDT, arteries displayed significantly increased endothelial lining (p = 0.02), which was more pronounced at 5 (p = 0.03) and 14 days (p = 0.02). At 30 days no relevant differences between PDT and control were noted. EC proliferation on PDT-treated matrix was significantly increased at 24, 48, and 72 h (p = 0.0004), whereas bFGF-mRNA expression was significantly increased at 24 h only (p = 0.007). CONCLUSION: Post-injury PDT appears to accelerate re-endothelialisation. Expression of bFGF-mRNA, however, although increased shortly after PDT, may not be responsible for a constant stimulation of EC proliferation.  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