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   83667篇
  免费   41133篇
  国内免费   33篇
耳鼻咽喉   1521篇
儿科学   4401篇
妇产科学   667篇
基础医学   16881篇
口腔科学   5264篇
临床医学   12806篇
内科学   24156篇
皮肤病学   7676篇
神经病学   14204篇
特种医学   2404篇
外科学   14225篇
综合类   43篇
一般理论   27篇
预防医学   4500篇
眼科学   1351篇
药学   5932篇
中国医学   1025篇
肿瘤学   7750篇
  2024年   6篇
  2023年   71篇
  2022年   152篇
  2021年   1428篇
  2020年   5157篇
  2019年   10956篇
  2018年   10258篇
  2017年   11548篇
  2016年   12276篇
  2015年   12128篇
  2014年   12067篇
  2013年   12609篇
  2012年   4591篇
  2011年   4553篇
  2010年   9159篇
  2009年   5564篇
  2008年   2483篇
  2007年   1360篇
  2006年   1368篇
  2005年   1144篇
  2004年   1131篇
  2003年   1098篇
  2002年   1115篇
  2001年   818篇
  2000年   733篇
  1999年   316篇
  1998年   133篇
  1997年   80篇
  1996年   80篇
  1995年   67篇
  1994年   54篇
  1993年   41篇
  1992年   31篇
  1991年   27篇
  1990年   17篇
  1989年   25篇
  1988年   12篇
  1987年   17篇
  1986年   26篇
  1985年   13篇
  1984年   12篇
  1983年   17篇
  1981年   7篇
  1979年   13篇
  1978年   9篇
  1977年   6篇
  1976年   6篇
  1974年   5篇
  1973年   5篇
  1972年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
This study tested whether combined therapy with melatonin and apoptotic adipose‐derived mesenchymal stem cells (A‐ADMSCs) offered additional benefit in ameliorating sepsis‐induced acute kidney injury. Adult male Sprague–Dawley rats (n = 65) were randomized equally into five groups: Sham controls (SC), sepsis induced by cecal‐ligation and puncture (CLP), CLP‐melatonin, CLP‐A‐ADMSC, and CLP‐melatonin‐A‐ADMSC. Circulating TNF‐α level at post‐CLP 6 hr was highest in CLP and lowest in SC groups, higher in CLP‐melatonin than in CLP‐A‐ADMSC and CLP‐melatonin‐A‐ADMSC groups (all P < 0.001). Immune reactivity as reflected in the number of splenic helper‐, cytoxic‐, and regulatory‐T cells at post‐CLP 72 hr exhibited the same pattern as that of circulating TNF‐α among all groups (P < 0.001). The histological scoring of kidney injury and the number of F4/80+ and CD14+ cells in kidney were highest in CLP and lowest in SC groups, higher in CLP‐melatonin than in CLP‐A‐ADMSC and CLP‐melatonin‐A‐ADMSC groups, and higher in CLP‐A‐ADMSC than in CLP‐melatonin‐A‐ADMSC groups (all P < 0.001). Changes in protein expressions of inflammatory (RANTES, TNF‐1α, NF‐κB, MMP‐9, MIP‐1, IL‐1β), apoptotic (cleaved caspase 3 and PARP, mitochondrial Bax), fibrotic (Smad3, TGF‐β) markers, reactive‐oxygen‐species (NOX‐1, NOX‐2), and oxidative stress displayed a pattern identical to that of kidney injury score among the five groups (all P < 0.001). Expressions of antioxidants (GR+, GPx+, HO‐1, NQO‐1+) were lowest in SC group and highest in CLP‐melatonin‐A‐ADMSC group, lower in CLP than in CLP‐melatonin and CLP‐A‐ADMSC groups, and lower in CLP‐melatonin‐ than in CLP‐A‐ADMSC‐tretaed animals (all P < 0.001). In conclusion, combined treatment with melatonin and A‐ADMSC was superior to A‐ADMSC alone in protecting the kidneys from sepsis‐induced injury.  相似文献   
996.
997.
998.
A flexible and simple Bayesian decision‐theoretic design for dose‐finding trials is proposed in this paper. In order to reduce the computational burden, we adopt a working model with conjugate priors, which is flexible to fit all monotonic dose‐toxicity curves and produces analytic posterior distributions. We also discuss how to use a proper utility function to reflect the interest of the trial. Patients are allocated based on not only the utility function but also the chosen dose selection rule. The most popular dose selection rule is the one‐step‐look‐ahead (OSLA), which selects the best‐so‐far dose. A more complicated rule, such as the two‐step‐look‐ahead, is theoretically more efficient than the OSLA only when the required distributional assumptions are met, which is, however, often not the case in practice. We carried out extensive simulation studies to evaluate these two dose selection rules and found that OSLA was often more efficient than two‐step‐look‐ahead under the proposed Bayesian structure. Moreover, our simulation results show that the proposed Bayesian method's performance is superior to several popular Bayesian methods and that the negative impact of prior misspecification can be managed in the design stage. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
999.
Introduction. Pulmonary atresia with ventricular septal defect (VSD) continues to be associated with significant morbidity and mortality, with significant institutional variation in therapeutic strategies. This study reports a single center experience utilizing an intensive transcatheter approach to promote pulmonary vascular growth. Methods. A retrospective analysis of 20 patients undergoing surgical and transcatheter treatment for pulmonary atresia with VSD between 2002 and 2010. Results. The median age at initial surgical palliation was 6.3 months (8 days to 2.5 years). Eleven patients (group 1) underwent initial surgical palliation without VSD closure and nine patients (group 2) underwent an initial complete repair with fenestrated or complete VSD closure. Group 1 had a smaller Nakata index (54 mm2/m2 vs. 134 mm2/m2, P= .04) and a smaller absolute native pulmonary artery diameter (2.7 mm vs. 4.5 mm, P= .01) than group 2. Intraoperative angiography was performed in 10 cases to evaluate if early transcatheter intervention was warranted. The median follow‐up during the study period was 2.3 years (1.6 months to 8.3 years). Of the 16 patients who survived the initial early postoperative period, 15 patients (94%) went on to receive surgical (n = 11) and/or interventional (n = 25) catheterization procedures. There was improvement in the mean Nakata index from the initial presurgical evaluation to the most recent catheterization data (38.4 mm2/m2 vs. 169.7 mm2/m2, P≤ .05). To date, two of 11 (18%) patients in group 1 ultimately underwent surgical VSD closure. Overall mortality was six of 20 (30%) with four deaths in group 1 and two deaths in group 2. There were no procedural deaths. Conclusions. Combining surgical unifocalization procedures with subsequent early and intensive catheter‐based pulmonary artery rehabilitation may improve vascular growth, ultimately rendering many patients suitable for fenestrated VSD closure. Risk stratification, including intraoperative exit angiography, is essential to determine the need for early transcatheter interventions.  相似文献   
1000.

Objective

To accurately estimate the prevalence of and the factors associated with uveitis in spondylarthritis (SpA) patients in France.

Methods

In an observational survey of SpA patients (diagnosis confirmed by the European Spondylarthropathy Study Group and/or Amor's criteria) consulting their rheumatologist for routine followup, we collected information regarding present/past history of uveitis, as well as detailed characteristics of the disease. Factors independently associated with uveitis were determined.

Results

From September 2008 to January 2009, 202 rheumatologists participated in the survey and recruited 902 patients (61% men) with a mean ± SD age of 45.3 ± 13.4 years and a mean ± SD disease duration of 10.4 ± 9.6 years. The SpA diagnoses were ankylosing spondylitis (71%), psoriatic arthritis (18%), or other SpA (11%). The HLA–B27 positivity rate was 76%. Uveitis prevalence was 32.2% (95% confidence interval [95% CI] 29.1–35.3%) since psoriasis and inflammatory bowel disease were 22.3% (95% CI 19.5–25.0%) and 8.6% (95% CI 6.7–10.5%), respectively. Recurrence of uveitis occurred in 52.3% and complications occurred in 11.7% of patients. Factors independently associated with uveitis were HLA–B27 positivity (adjusted odds ratio [ORadj] 2.97 [95% CI 1.83–4.81], P < 0.0001) and disease duration (ORadj 1.28 [95% CI 1.16–1.41], P < 0.0001 for ≥10 years).

Conclusion

Results indicate that uveitis is the most common extraarticular feature of SpA, occurring preferentially in HLA–B27–positive patients over the entire course of the disease.  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