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   1796篇
  免费   84篇
  国内免费   10篇
耳鼻咽喉   8篇
儿科学   37篇
妇产科学   101篇
基础医学   210篇
口腔科学   3篇
临床医学   169篇
内科学   539篇
皮肤病学   56篇
神经病学   102篇
特种医学   41篇
外科学   161篇
综合类   19篇
一般理论   1篇
预防医学   56篇
眼科学   57篇
药学   174篇
中国医学   59篇
肿瘤学   97篇
  2023年   5篇
  2022年   6篇
  2021年   24篇
  2020年   14篇
  2019年   22篇
  2018年   33篇
  2017年   13篇
  2016年   20篇
  2015年   43篇
  2014年   51篇
  2013年   72篇
  2012年   124篇
  2011年   99篇
  2010年   91篇
  2009年   65篇
  2008年   102篇
  2007年   149篇
  2006年   135篇
  2005年   119篇
  2004年   88篇
  2003年   84篇
  2002年   86篇
  2001年   85篇
  2000年   55篇
  1999年   62篇
  1998年   27篇
  1997年   13篇
  1996年   15篇
  1995年   11篇
  1994年   16篇
  1993年   9篇
  1992年   29篇
  1991年   25篇
  1990年   24篇
  1989年   7篇
  1988年   14篇
  1987年   19篇
  1986年   7篇
  1985年   13篇
  1984年   6篇
  1983年   3篇
  1981年   1篇
  1977年   1篇
  1975年   2篇
  1974年   1篇
排序方式: 共有1890条查询结果,搜索用时 31 毫秒
31.
Nobiletin, a bioactive polymethoxylated flavone (5,6,7,8,3',4'‐hexamethoxyflavone), is abundant in citrus fruit peel. Although nobiletin exhibits antitumor activity against various cancer cells, the effect of nobiletin on glioma cells remains unclear. The aim of this study was to determine the effects of nobiletin on the human U87 and Hs683 glioma cell lines. Treating glioma cells with nobiletin (20–100 µm ) reduced cell viability and arrested the cell cycle in the G0/G1 phase, as detected using a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay and propidium iodide (PI) staining, respectively; however, nobiletin did not induce cell apoptosis according to PI‐annexin V double staining. Data from western blotting showed that nobiletin significantly attenuated the expression of cyclin D1, cyclin‐dependent kinase 2, cyclin‐dependent kinase 4, and E2 promoter‐binding factor 1 (E2F1) and the phosphorylation of Akt/protein kinase B and mitogen‐activated protein kinases, including p38, extracellular signal‐regulated kinase, and c‐Jun N‐terminal kinase. Our data also showed that nobiletin inhibited glioma cell migration, as detected by both functional wound healing and transwell migration assays. Altogether, the present results suggest that nobiletin inhibits mitogen‐activated protein kinase and Akt/protein kinase B pathways and downregulates positive regulators of the cell cycle, leading to subsequent suppression of glioma cell proliferation and migration. Our findings evidence that nobiletin may have potential for treating glioblastoma multiforme. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
32.
ObjectivesToll-like receptors (TLRs) are molecules conserved in evolution for detecting pathogen invasions and tissue damage and are involved in atherogenesis. This study explores the mRNA expression of TLRs and their probable role in further disease occurrence among ischemic stroke patients.Design and MethodsA total of 89 ischemic stroke patients and 166 controls were recruited for this study. Total RNA was extracted and mRNA was reverse-transcribed to cDNA and was analyzed for TLRs and interleukin 8 (IL8).ResultsThe TLR4 mRNA expression level is significantly higher in the stroke group. Conversely, IL-8 mRNA levels decreased significantly in the patient group.ConclusionOur results suggest that TLR4 overexpression in mRNA levels is observed in stroke patients, which might account for the probable inflammatory injury before or after stroke. A reduction of IL-8 expression could result from the downregulatory effects of aspirin.  相似文献   
33.
34.
35.
36.
37.

Background

Lead (Pb) exposure and obesity are co-occurring risk factors for decreased bone mass in the young, particularly in low socioeconomic communities.

Objectives

The goal of this study was to determine whether the comorbidities of Pb exposure and high-fat diet–induced obesity amplify skeletal deficits independently associated with each of these risk factors, and to explore associated mechanisms of the observed deficiencies.

Methods

Five-week-old male C57BL/6J mice were placed on low-fat (10% kcal, LFD) or high-fat (60% kcal, HFD) diets for 12 weeks. Mice were exposed to lifetime Pb (50 ppm) through drinking water.

Results

HFD was associated with increased body mass and glucose intolerance. Both HFD and Pb increased fasting glucose and serum leptin levels. Pb and HFD each reduced trabecular bone quality and together had a further detrimental effect on these bone parameters. Mechanical bone properties of strength were depressed in Pb-exposed bones, but HFD had no significant effect. Both Pb and HFD altered progenitor cell differentiation, promoting osteoclastogenesis and increasing adipogenesis while suppressing osteoblastogenesis. In support of this lineage shift being mediated through altered Wnt signaling, Pb and non-esterified fatty acids in MC3T3 cells increased in vitro PPAR-γ activity and inhibited β-catenin activity. Combining Pb and non-esterified fatty acids enhanced these effects.

Conclusions

Pb and HFD produced selective deficits in bone accrual that were associated with alterations in progenitor cell activity that may involve reduced Wnt signaling. This study emphasizes the need to assess toxicants together with other risk factors relevant to human health and disease.

Citation

Beier EE, Inzana JA, Sheu TJ, Shu L, Puzas JE, Mooney RA. 2015. Effects of combined exposure to lead and high-fat diet on bone quality in juvenile male mice. Environ Health Perspect 123:935–943; http://dx.doi.org/10.1289/ehp.1408581  相似文献   
38.
39.

Purpose:

The purpose of this study is to identify the possible factors for preserving the eyes after late or suboptimally treated endogenous endophthalmitis secondary to Klebsiella pneumoniae (KP) liver abscess.

Methods:

A retrospective chart review was conducted for patients admitted with KP liver abscess from January 1991 to June 2012.

Results:

Six hundred and ninety-three patients with KP liver abscess were recorded, in which endophthalmitis was identified in 53 cases (65 eyes, 8.29%). Diabetes was significantly associated with the development of endophthalmitis (p = 0.014). Eleven eyes received their last ocular treatment ≥10 days and final vision ≥ counting fingers, and were defined as benign type KP endophthalmitis. The absence of diabetes was the only consistent candidate factor for benign type KP endophthalmitis.

Conclusion:

A lack of ongoing diabetes is an important factor in preserving eyes with late or suboptimally treated endogenous endophthalmitis second to KP liver abscess.  相似文献   
40.
Several studies have shown cardiovascular benefit in treating hypercholesterolemia with HMG-CoA reductase inhibitor. However, in addition to the lowering of cholesterol, the beneficial effects of this inhibitor reflect other pharmacological activities. Whether these beneficial effects are partly mediated by changes in fibrinolytic factors remains to be proven, since clinical studies on the effects of HMG-CoA reductase inhibitors on fibrinolytic factors have not yielded consistent results. The purpose of this study was to evaluate the effects of fluvastatin on fibrinolytic factors in hypercholesterolemic patients. After 6 weeks on a low-fat, low-cholesterol diet, 23 outpatients known to have primary hypercholesterolemia with low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl with at least 2 risk factors or fasting LDL-C > or = 160 mg/dl were selected for the study. Venous blood samples were collected at baseline and at 8 weeks after fluvastatin therapy (40 mg/day) to measure of tissue plasminogen activator (t-PA), plasminogen activators inhibitor-1 (PAI-1), fibrinogen, D-dimer and lipid profile. After 8 weeks of therapy, fluvastatin reduced serum cholesterol by 11% (261.9 mg/dl vs 233.2 mg/dl, P < 0.01) and LDL-C by 22% (191.9 mg/dl vs 149.3 mg/dl, P < 0.01). D-dimer was significantly decreased (0.38 ng/L vs 0.28 ng/L, P = 0.02) and tPA, PAI-1 and fibrinogen tended to decrease after therapy. Fluvastatin therapy improved fibrinolytic profile; the result of this study may in part explain the benefit of HMG-CoA reductase inhibitor on cardiovascular system other than lipid lowering.  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