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   33358篇
  免费   2079篇
  国内免费   202篇
耳鼻咽喉   314篇
儿科学   560篇
妇产科学   450篇
基础医学   4650篇
口腔科学   887篇
临床医学   3431篇
内科学   7085篇
皮肤病学   662篇
神经病学   3709篇
特种医学   1952篇
外科学   5297篇
综合类   184篇
一般理论   7篇
预防医学   1407篇
眼科学   686篇
药学   1956篇
中国医学   68篇
肿瘤学   2334篇
  2024年   28篇
  2023年   268篇
  2022年   515篇
  2021年   887篇
  2020年   626篇
  2019年   811篇
  2018年   929篇
  2017年   798篇
  2016年   926篇
  2015年   1131篇
  2014年   1360篇
  2013年   1646篇
  2012年   2679篇
  2011年   2786篇
  2010年   1670篇
  2009年   1490篇
  2008年   2377篇
  2007年   2380篇
  2006年   2224篇
  2005年   2169篇
  2004年   1959篇
  2003年   1785篇
  2002年   1646篇
  2001年   286篇
  2000年   201篇
  1999年   261篇
  1998年   312篇
  1997年   232篇
  1996年   184篇
  1995年   158篇
  1994年   129篇
  1993年   122篇
  1992年   70篇
  1991年   56篇
  1990年   55篇
  1989年   37篇
  1988年   36篇
  1987年   28篇
  1986年   28篇
  1985年   25篇
  1984年   39篇
  1983年   26篇
  1982年   32篇
  1981年   27篇
  1980年   17篇
  1978年   12篇
  1977年   12篇
  1974年   9篇
  1931年   7篇
  1927年   8篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
2.
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis.  相似文献   
3.
4.
5.
6.
Introduction: Pharmacological options to address the imbalance between bone resorption and accrual in osteoporosis include anti-resorptive and osteoanabolic agents. Unique biologic pathways such as the Wnt/β-catenin pathway have been targeted in the quest for new emerging therapeutic strategies.

Areas covered: This review provides an overview of existing pharmacotherapy for osteoporosis in women and explore state-of–the-art and emerging therapies to prevent bone loss, with an emphasis on the mechanism of action, indications and side effects.

Expert opinion: Bisphosphonates appear to be a reliable and cost-effective option, whereas denosumab has introduced a simpler dosing regimen and may achieve a linear increase in bone mineral density (BMD) with no plateau being observed, along with continuous anti-fracture efficacy. Abaloparatide, a parathyroid-hormone-related peptide (PTHrP)-analogue, approved by the FDA in April 2017, constitutes the first new anabolic osteoporosis drug in the US for nearly 15 years and has also proven its anti-fracture efficacy. Romosozumab, a sclerostin inhibitor, which induces bone formation and suppresses bone resorption, has also been developed and shown a significant reduction in fracture incidence; however, concerns have arisen with regard to increased cardiovascular risk.  相似文献   

7.
8.
BACKGROUND: Common clinical forms of oral lichen planus (OLP) and oral lichenoid reactions (OLR) are erythematous (ERY) or reticular (RET). The purpose of this study was to find histopathological changes that differ between these forms. METHODS: Epithelial thickness, epithelial proliferation rate, apoptosis, and HLA-DR expression were compared among 10 reticular and 12 erythematous lesions, and 11 normal oral mucosa samples (NOM). RESULTS: The epithelium in ERY was thinner than in NOM, whereas RET showed values between ERY and NOM. Cell proliferation increased significantly in ERY as compared with RET and NOM, with no difference between RET and NOM. Relative numbers of epithelial cell nuclei displaying visible chromatin condensation were reduced in ERY form. CONCLUSIONS: The markedly increased cell proliferation in ERY supports the notion that this form displays a higher disease activity as compared to RET. It can therefore be important to study each disease form separately.  相似文献   
9.
Lymphocyte-predominant Hodgkin’s lymphoma (LPHL) differs in histologic and clinical presentation from classical Hodgkin’s lymphoma (cHL). Treatment of LPHL patients using standard Hodgkin’s lymphoma protocols leads to complete remission in more than 95% of patients. Survival and freedom from treatment failure are substantially worse in advanced-stage patients than for early-stage patients. Thus, patients in advanced stages and those in early stages with unfavorable risk factors should be treated similar to those with cHL. In contrast, patients with early-stage LPHL without risk factors might be sufficiently treated with reduced-intensity programs having less severe adverse effects. As a result, treatment of early LPHL is rather heterogeneous, including radiotherapy using extended-fleld technique, involved-fleld radiotherapy (IF-RT), combined-modality treatment, and, more recently, monoclonal antibodies. Watch-and-wait strategy plays an important role in pediatric oncology, to avoid adverse effects associated with therapy. IF-RT seems to be emerging as a treatment of choice for patients with stage IA LPHL; most larger study groups, such as the German Hodgkin Study Group and the European Organisation for Research and Treatment of Cancer, have adopted IF-RT as the treatment of choice for these patients.  相似文献   
10.
INTRODUCTION H pylori infection is an established risk factor for development of gastric cancer[1,2]. According to the model of carcinogenesis of the intestinal type adenocarcinoma proposed by Correa, the multi-step development starts from the condition o…  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