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   46001篇
  免费   4405篇
  国内免费   2450篇
耳鼻咽喉   551篇
儿科学   594篇
妇产科学   449篇
基础医学   6093篇
口腔科学   632篇
临床医学   4945篇
内科学   7825篇
皮肤病学   1321篇
神经病学   2860篇
特种医学   2509篇
外国民族医学   7篇
外科学   4806篇
综合类   5187篇
现状与发展   5篇
一般理论   5篇
预防医学   2627篇
眼科学   1201篇
药学   5062篇
  18篇
中国医学   2610篇
肿瘤学   3549篇
  2024年   204篇
  2023年   751篇
  2022年   1808篇
  2021年   2325篇
  2020年   1495篇
  2019年   1588篇
  2018年   1737篇
  2017年   1534篇
  2016年   1833篇
  2015年   2408篇
  2014年   2832篇
  2013年   2794篇
  2012年   3933篇
  2011年   3972篇
  2010年   2540篇
  2009年   2044篇
  2008年   2465篇
  2007年   2336篇
  2006年   2111篇
  2005年   2049篇
  2004年   1507篇
  2003年   1574篇
  2002年   1379篇
  2001年   1068篇
  2000年   887篇
  1999年   702篇
  1998年   403篇
  1997年   371篇
  1996年   289篇
  1995年   230篇
  1994年   229篇
  1993年   153篇
  1992年   176篇
  1991年   182篇
  1990年   166篇
  1989年   150篇
  1988年   108篇
  1987年   100篇
  1986年   90篇
  1985年   63篇
  1984年   34篇
  1983年   16篇
  1982年   16篇
  1981年   29篇
  1980年   29篇
  1979年   31篇
  1978年   12篇
  1977年   13篇
  1969年   7篇
  1967年   7篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
1.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  相似文献   
2.
The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental–isoflurane (TI), medetomidine–ketamine (MK), and xylazine–ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m2), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m2), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.  相似文献   
3.
A patient with skeletal Class III malocclusion was treated in 2 phases during the early permanent dentition. In phase 1, maxillary protraction was combined with rapid palatal expansion; in phase 2, fixed appliances were placed. The results were good posttreatment, and, 1 year later, a favorable growth tendency could be observed. This report shows that treatment for a patient with skeletal Class III malocclusion can be started in the early permanent dentition, with very good final results.  相似文献   
4.
Transforminggrowthfactor-β1(TGF-β1)is amultifunctionalpolypeptidethatregulatesanum-berofcellularprocesses,includingcellprolifera-tion,differentiation,apoptosis,migration,matrix synthesis,andtheimmuneresponse[1,2].Inchron-icrenaldiseases,TGF-β1isakeymediatorofex-tracellularmatrix(ECM)accumulation[3].Oneof thetargetrenalcellsforTGF-β1isglomerular mesangialcellsthatarecapableofproducingcom-ponentsofECM,suchascollagens,lamininand fibronectin[4,5].Recentstudiesindicatedthatinhi-bitionofT…  相似文献   
5.
There have been a few studies and inconsistent results regarding the coincidence of Parkinson's disease (PD) and atherosclerotic diseases, such as cerebrovascular disease. Carotid intima-media thickness (IMT) is a known marker for subclinical atherosclerosis. The aim of this study was to investigate the carotid IMT between PD patients and controls. We studied 43 patients with PD and 86 matched controls. The carotid IMT in PD patients was significantly smaller than in controls (0.796 +/- 0.179 mm vs. 0.913 +/- 0.237 mm, P < 0.05). In multivariate analysis, the carotid IMT was inversely associated with the duration of levodopa medication and the severity of PD. These results suggest that PD patients have a lower risk of atherosclerosis.  相似文献   
6.
护理作为一门独立的专业,其发展应以科学研究为基础。护理科研、论文的数量和水平是评价一个地区或单位的护理整体水平的重要指标之一。笔者通过我院10年间医院工作人员科研立项、科研论文发表交流情况及护理人员论文写作的调查,对护理科研滞后的应用进行了综合分析,认为缺乏科研意识、科研潜力不足,观行制度制约,客观条件制约是重要因素。提出改变这种状态应从学科带头人入手,详细阐述了护士长对护理科研、论文工作的指导。  相似文献   
7.
The FIGNL1 gene was proven to be a new subfamily member of ATPases associated with diverse cellular activities (AAA proteins). In this in vitro study, the AAA proteins inhibited osteoblast proliferation and stimulated osteoblast differentiation. We showed that FIGNL1 may play some regulatory role in osteoblastogenesis. INTRODUCTION: The fidgetin-like 1 (FIGNL1) gene encodes a new subfamily member of ATPases associated with diverse cellular activities (AAA proteins). Although the FIGNL1 protein localizes to both the nucleus and cytoplasm, the function of FIGNL1 remains unknown. In a previous study, we identified several genes that mediate the anabolic effects of basic fibroblast growth factor (bFGF) on bone by using microarray data. FIGNL1 was one of the genes that downregulated >2-fold in MC3T3-E1 cells after treatment with bFGF. Therefore, this study was aimed to identify and confirm the function of FIGNL1 on osteoblastogenesis. MATERIALS AND METHODS: We examined the effect of the FIGNL1 gene on proliferation, differentiation, and apoptosis in mouse osteoblast cells (MC3T3-E1 and mouse primary calvarial cells) using flow cytometry, RT-PCR, cell proliferation assay, and cell death assay. MC3T3-E1 cells and mouse calvarial cells were transfected with small interfering RNA (siRNA) directed against the FIGNL1 or nontargeting control siRNA and examined by cell proliferation and cell death assays. Also, FIGNL1 was fused to enhance green fluorescent protein (EGFP), and the EGFP-fused protein was transiently expressed in MC3T3-E1 cells. RESULTS: Reduced expression of FIGNL1 by bFGF and TGF-beta1 treatment was verified by RT-PCR analysis. Overexpression of FIGNL1 reduced the proliferation of MC3T3-E1 and calvarial cells, more than the mock transfected control cells did. In contrast, siFIGNL1 transfection significantly increased the proliferation of osteoblasts, whereas overexpression of FIGNL1 did not seem to alter apoptosis in osteoblasts. Meanwhile, overexpression of FIGNL1 enhanced the mRNA expression of alkaline phosphatase (ALP) and osteocalcin (OCN) in osteoblasts. In contrast, siFIGNL1 decreased the expression of ALP and OCN. A pEGFP-FIGNL1 transfected into MCT3-E1 cells had an initially ubiquitous distribution and rapidly translocated to the nucleus 1 h after bFGF treatment. CONCLUSIONS: From these results, we proposed that FIGNL1, a subfamily member of the AAA family of proteins, might play some regulatory role in osteoblast proliferation and differentiation. Further analyses of FIGNL1 will be needed to better delineate the mechanisms contributing to the inhibition of proliferation and stimulation of osteoblast differentiation.  相似文献   
8.
雷公藤多甙联合中草药治疗IgA肾病的病例对照研究   总被引:4,自引:0,他引:4  
李激 《疾病控制杂志》2006,10(4):414-415
IgA肾病(immunoglobulin A nephropathy,I-gAN)是肾小球系膜病变的一个特殊类型,其发病机制尚未完全明确,临床表现复杂多样。目前,临床上常用的药物主要有激素、雷公藤、环磷酰胺等,都具有一定的疗效,但在药物副作用、血尿的消退、肾功能的稳定及停药后复发等方面均有各自的缺陷。笔者所在科室在慢性肾炎型IgAN的治疗上进行探索,现将结果报告如下。1资料与方法1.1病例选择及分组73例均为铜陵市第一人民医院肾内科住院并经肾活检证实的IgAN患者,除外各种继发性IgAN,并符合以下条件:①按Lee氏分级均在Ⅲ~Ⅳ级间;②无严重的肝损害;③血…  相似文献   
9.
In order to investigate the antagonistic effect of Glycyrrhiza Uralensis Fish (GUF) and Chelidonium maJus L (CML) on gastrccarcinogenesis induced by MNNG in Wastar rats, we treated the rats with MNNG alone (group 1) and with MNNG plus GUF and CML (group 2 and 3) respectively. The incidence of infiltrating adenocarcinoma of the glandular stomach and duodenum in group 2 was significantly lower than that in group 1 (26.7% vs. 67.8%). The differentiation and aggressivenees of carcinomas occured in group 2 were much better and mild than those in group 1. Present study also demonstrated that the inhibitory effect of CML on proliferation of human stomach carcinoma cell line MGC-803 was very remarkable; in addition, GUF and CML were able to antagonise the mutagenic activation of MNNG. These results suggest that GUF and CML may be empoyed in prevention of gastric carcinoma.  相似文献   
10.
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