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   5798篇
  免费   335篇
  国内免费   33篇
耳鼻咽喉   135篇
儿科学   185篇
妇产科学   174篇
基础医学   994篇
口腔科学   61篇
临床医学   452篇
内科学   1296篇
皮肤病学   163篇
神经病学   573篇
特种医学   75篇
外科学   434篇
综合类   31篇
一般理论   1篇
预防医学   501篇
眼科学   99篇
药学   613篇
中国医学   13篇
肿瘤学   366篇
  2023年   57篇
  2022年   272篇
  2021年   382篇
  2020年   147篇
  2019年   200篇
  2018年   198篇
  2017年   186篇
  2016年   201篇
  2015年   220篇
  2014年   253篇
  2013年   349篇
  2012年   522篇
  2011年   541篇
  2010年   268篇
  2009年   212篇
  2008年   321篇
  2007年   333篇
  2006年   347篇
  2005年   281篇
  2004年   244篇
  2003年   216篇
  2002年   206篇
  2001年   21篇
  2000年   9篇
  1999年   16篇
  1998年   22篇
  1997年   17篇
  1996年   22篇
  1995年   12篇
  1994年   17篇
  1993年   4篇
  1992年   9篇
  1991年   3篇
  1989年   3篇
  1988年   3篇
  1987年   3篇
  1985年   3篇
  1983年   5篇
  1982年   5篇
  1981年   4篇
  1980年   2篇
  1975年   3篇
  1974年   3篇
  1972年   3篇
  1971年   2篇
  1968年   2篇
  1965年   2篇
  1963年   2篇
  1947年   1篇
  1940年   1篇
排序方式: 共有6166条查询结果,搜索用时 15 毫秒
81.
82.
BACKGROUND: The risk of atherosclerosis and its complications differs between male and female subjects. This is probably associated with gender differences in endothelial function as reflected by endothelium-dependent vasodilation. The aim of the study was to compare flow-mediated dilatation (FMD) in males and females with coronary artery disease (CAD), and to determine factors that might potentially influence FMD. METHODS: Ninety-six patients with stable CAD (CCS II-III): 76 males (mean age: 57.7 +/- 10 years) and 20 postmenopausal females (mean age: 60.1 +/- 10 years) were included into the study. Clinical data, pharmacotherapy, concomitant diseases, and FMD were all assessed. FMD was measured with high-resolution ultrasound as the percent change of brachial artery diameter (BAd) after a 3-minute occlusion (%FMD), and following the administration of 0.4 mg sublingual nitroglycerin (%NTG-MD). RESULTS: The percentage of FMD was significantly decreased (P < 0.05), and BAd was significantly larger (P < 0.001) in males as compared to females. Clinical data, pharmacotherapy, and concomitant diseases were comparable in the study groups.In all subjects examined, %FMD was related to BAd (r =-0.415, P < 0.001) and the percentage of ejection fraction (EF%) (r = 0.325, P < 0.01) in the univariate analysis, and to BAd only (r =-0.343, P < 0.01) in the multivariate analysis. The percentage of nitroglycerine-mediated vasodilatation (NTG-MD) correlated negatively with BAd (r =-0.430, P < 0.001), and positively with EF% (r = 0.334, P < 0.01) in the univariate analysis, and with BAd (r =-0.288, P < 0.05) in the multivariate analysis. Index %FMD x BAd was comparable for male and female subjects. CONCLUSIONS: Males and postmenopausal females with CAD show differences in endothelium-dependent vasodilatation that seem to secondarily result from differences in the BAd. Objective comparison of %FMD is only possible between patients with the same brachial artery size.  相似文献   
83.
84.
Background The impact of age on melanoma patient outcomes is uncertain. Objective The aim of the study was to analyze the characteristics and treatment outcomes in cutaneous melanoma patients ≥ 65 years of age with lymph node metastases. Methods We analyzed data from 849 consecutive patients with stage III cutaneous melanoma who were treated between 1994 and 2007 at one institution. Of these, 225 (26.5%) were ≥ 65 years of age. The characteristics and disease‐specific survival (DSS) from lymph node dissection (LND) date of patients ≥ 65 years of age were compared with those of younger patients. Median follow‐up time was 49 months (range: 6–140 months). Results In the ≥ 65 years group (51.6% men), the median Breslow thickness was 5.0 mm and 70% was ulcerated. The 5‐year DSS rate was significantly lower in older patients (34%). Multivariate analysis identified older age as an independent prognostic factor for DSS in the overall group. Independent negative prognostic factors of DSS in the group of older stage III patients were identified as features of nodal metastases (extracapsular invasion, HR = 1.74, P = 0.009; and ≥ 4 involved lymph nodes, HR = 1.5; P = 0.008) and male sex (HR = 1.5; P = 0.039). Conclusions This analysis showed that melanoma patients ≥ 65 years of age are characterized by a higher primary tumor stage and worse prognosis in the presence of regional node metastases than younger patients. Additionally, the results indicate that the same radical surgical therapy is necessary for patients ≥ 65 years old as in younger patients.  相似文献   
85.
86.
A case of a 51-year-old woman with symptoms of non-ST-segment elevation acute coronary syndrome and concomitant atrial flutter is presented. Patient underwent atrioventricular septal defect repair in childhood. Coronary angiography showed total occlusion of left main coronary artery and massive collateral network originating from right coronary artery supplying entire left coronary artery. Ablation of atrial flutter had been performed and patient was subsequently submitted to mitral valve replacement, tricuspid valvuloplasty and coronary artery bypass grafting. The potential causes of left main occlusion are in this case discussed.  相似文献   
87.
Although in apoE/LDLR(-/-) mice atherosclerotic plaques develop spontaneously, various atherogenic diets (e.g. Western diet) are frequently used to accelerate the disease in this model. The objective of this study was to compare the effects on atherosclerosis of Western diet and other types of high-fat, high cholesterol, hypertriglyceridemic diets with the effects of the low carbohydrate, high protein (LCHP) diet. 16-18 week old mice with pre-established atherosclerosis were assigned to experimental groups and fed for the next 10 weeks with control diet, margarine diet (margarine 7%), hypertrigliceridemic diet (fructose 62%), high-fat diet (Western diet), high cholesterol diet (egg yolk diet) or with LCHP diet. No differences in body weight were observed among experimental groups. Plasma cholesterol concentration was significantly increased in egg yolk diet- and LCHP diet-fed apoE/LDLR(-/-) mice as compared to other types of diets. Plasma concentration of triacylglycerols was significantly elevated in egg yolk diet- and LCHP diet-fed apoE/LDLR(-/-) mice. The area of atherosclerotic plaques in the aortic root was substantially increased in LCHP diet-fed mice as compared to other types of diets. Furthermore, in brachiocephalic arteries of LCHP diet-fed mice there was evidence of plaque rupture. In conclusion, the LCHP diet promoted atherosclerosis in apoE/LDLR(-/-) mice more intensively than classical Western diet and favored the development of unstable lesions.  相似文献   
88.
A PCR procedure based on the intergenic region (IR) separating two genes encoding a recently identified mycobacterial two-component system, named SenX3-RegX3, was developed and was shown to be suitable for identifying Mycobacterium bovis BCG. The senX3-regX3 IR contains a novel type of repetitive sequence, called mycobacterial interspersed repetitive units (MIRUs). All tested BCG strains exclusively contained 77-bp MIRUs within the senX3-regX3 IR, whereas all non-BCG M. tuberculosis complex strains contained a 53-bp MIRU, in addition to the 77-bp MIRUs. All 148 strains analyzed so far could be divided into eight different groups according to the copy numbers of the 77-bp MIRU and to the presence or absence of the 53-bp MIRU. BCG strains contained either one, two, or three 77-bp MIRUs. The other strains contained one to five 77-bp MIRUs invariably followed by a 53-bp MIRU. The consistent absence of the 53-bp MIRU in BCG strains and its presence in virulent strains allowed us to develop an enzyme-linked immunosorbent assay using specific capture oligonucleotide probes to distinguish between BCG and other M. tuberculosis complex strains.  相似文献   
89.
Gray matter pathology is increasingly recognized as an important feature of multiple sclerosis (MS), but the nature of the immune response that targets the gray matter is poorly understood. Starting with a proteomics approach, we identified contactin-2/transiently expressed axonal glycoprotein 1 (TAG-1) as a candidate autoantigen recognized by both autoantibodies and T helper (Th) 1/Th17 T cells in MS patients. Contactin-2 and its rat homologue, TAG-1, are expressed by various neuronal populations and sequestered in the juxtaparanodal domain of myelinated axons both at the axonal and myelin sides. The pathogenic significance of these autoimmune responses was then explored in experimental autoimmune encephalitis models in the rat. Adoptive transfer of TAG-1–specific T cells induced encephalitis characterized by a preferential inflammation of gray matter of the spinal cord and cortex. Cotransfer of TAG-1–specific T cells with a myelin oligodendrocyte glycoprotein-specific mAb generated focal perivascular demyelinating lesions in the cortex and extensive demyelination in spinal cord gray and white matter. This study identifies contactin-2 as an autoantigen targeted by T cells and autoantibodies in MS. Our findings suggest that a contactin-2–specific T-cell response contributes to the development of gray matter pathology.  相似文献   
90.
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