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   1098篇
  免费   76篇
  国内免费   14篇
耳鼻咽喉   6篇
儿科学   33篇
妇产科学   41篇
基础医学   147篇
口腔科学   36篇
临床医学   128篇
内科学   241篇
皮肤病学   12篇
神经病学   82篇
特种医学   18篇
外科学   96篇
综合类   39篇
现状与发展   1篇
一般理论   1篇
预防医学   118篇
眼科学   5篇
药学   66篇
中国医学   9篇
肿瘤学   109篇
  2024年   2篇
  2023年   6篇
  2022年   24篇
  2021年   31篇
  2020年   26篇
  2019年   33篇
  2018年   23篇
  2017年   10篇
  2016年   27篇
  2015年   25篇
  2014年   26篇
  2013年   65篇
  2012年   80篇
  2011年   90篇
  2010年   47篇
  2009年   49篇
  2008年   80篇
  2007年   61篇
  2006年   75篇
  2005年   83篇
  2004年   55篇
  2003年   44篇
  2002年   56篇
  2001年   29篇
  2000年   22篇
  1999年   16篇
  1998年   4篇
  1997年   6篇
  1996年   2篇
  1995年   7篇
  1994年   7篇
  1993年   5篇
  1992年   6篇
  1991年   11篇
  1990年   8篇
  1989年   9篇
  1988年   7篇
  1987年   7篇
  1986年   3篇
  1985年   4篇
  1984年   4篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1976年   2篇
排序方式: 共有1188条查询结果,搜索用时 531 毫秒
101.

Introduction  

Checkpoint kinase 2 (CHEK2) is a moderate penetrance breast cancer risk gene, whose truncating mutation 1100delC increases the risk about twofold. We investigated gene copy-number aberrations and gene-expression profiles that are typical for breast tumors of CHEK2 1100delC-mutation carriers.  相似文献   
102.
遗传性非息肉病性大肠癌30例临床病理特点与诊治分析   总被引:1,自引:0,他引:1  
目的:探讨遗传性非息肉病性大肠癌(hereditary nonpolyposis colorectal cancer,HNPCC)的临床病理及分子病理特征,提高对该病的认识和诊疗水平。方法:回顾性分析中南大学湘雅医院普通外科诊治的30例HNPCC病人,以同期在该院治疗的散发性结直肠癌25例为对照组。比较其发病年龄、肿瘤部位、病理类型、治疗方法及预后。采用免疫组织化学检测两组病人错配修复基因(mismatch repair genes,MMR)MLH1和 MSH2 表达缺失率。结果:与对照组相比,HNPCC组的发病年龄早,近段大肠癌比例高,易于合并多发癌,肿瘤高分化类型所占比例高(P<0.05)。MLH1和 MSH2 表达缺失率高于对照组(P<0.05)。HNPCC组中1/3的病人接受了大肠次全切除术,预后与散发大肠癌相当(P>0.05)。结论:HNPCC具有发病早,易合并多发癌的特点,结合MMR的检测可提高诊断的准确率。彻底手术和密切随访可取得好的效果。  相似文献   
103.
The aim of this study was to assess the dopamine function of the temporal cortex in major depressive disorder using [123I]epidepride to image D2/3 receptor binding sites. Ten major depressives and 10 healthy controls were selected from a general population sample for single-photon emission computed tomography imaging. Among the major depressives there was a strong bilateral correlation between the scores on the 21-item Hamilton Depression Rating Scale and D2/3 receptor binding. Dopaminergic abnormalities may be present in the temporal cortices of major depressives.  相似文献   
104.
OBJECTIVES: To find out whether autoantibodies to citrullinated telopeptides of type I and II collagens and to cyclic citrullinated peptides (CCPs) predict the development of rheumatoid arthritis (RA). METHODS: A case-control study (matched for sex, age and municipality) was nested within a Finnish cohort of 19072 adults who had neither arthritis nor a history of it at the baseline examination during 1973-7. 124 subjects developed RA by late 1989, and of these, 89 were positive for rheumatoid factor (RF). Preillness serum specimens were analysed for autoantibodies against arginine (A)- or citrulline (C)-containing synthetic telopeptides using a chemiluminescence method and for anti-CCPs Mark2 with an enzyme-linked immunosorbent assay method. RESULTS: The mean levels of autoantibodies to citrulline-containing telopeptides and the C/A ratios of type I and II collagens and to CCP were higher in subjects who later developed RF-positive RA. In the highest tertiles of C/A (I), C/A (II) ratios and anti-CCPs levels, the relative risk of RF-positive RA was significantly increased. In the multifactorial model, only anti-CCPs retained its statistical significance. However, the interaction term of C/A (II) ratio and anti-CCPs proved to be statistically significant (p = 0.02). The subjects ranked into the highest tertiles of both C/A (II) ratio and anti-CCPs had an odds ratio of 20.06 (95% confidence interval, 4.37 to 92.06) of developing RF-positive RA compared with those in the lowest tertiles of these antibodies. None of the autoantibodies predicted RF-negative RA. CONCLUSION: Autoantibodies to citrullinated telopeptides of type I and II collagen and to CCPs exert a synergistic effect on the risk of seropositive RA.  相似文献   
105.
BACKGROUND: Our objective was to investigate whether serum concentrations of asymmetric dimethylarginine (ADMA) or l-arginine correlate to hyperlipidemia or endothelial function in normal pregnancy compared with the non-pregnant subjects. METHODS AND RESULTS: As a part of population-based, prospective cohort Cardiovascular Risk in Young Finns study conducted in Finland we examined 57 pregnant Finnish women throughout gestation and 62 control women matched for age and smoking. Serum glucose, triglycerides (TG), total cholesterol (TC), low-density cholesterol (LDL-C), high-density cholesterol (HDL-C) and ADMA, symmetric dimethylarginine (SDMA) and l-arginine were determined concomitantly with endothelium-dependent brachial artery flow-mediated dilation (FMD), measured by ultrasound. All serum lipid concentrations were significantly higher in pregnant women than in non-pregnant women (P < 0.001 for each). The mean serum ADMA concentration in pregnant women was significantly lower compared with the non-pregnant controls (0.513 micromol l(-1) +/- 0.0593 versus 0.577 micromol l(-1) +/- 0.0710, P < 0.001). Lowered ADMA concentrations did not correlate statistically to FMD in these healthy pregnant women but FMD was enhanced towards the end of pregnancy. CONCLUSIONS: ADMA and l-arginine concentrations fall in normal pregnancy despite marked hypercholesterolemia. Endothelium-dependent vasodilation is enhanced in normal pregnancy but is not statistically correlated to maternal serum ADMA or l-arginine concentrations.  相似文献   
106.
The aim of the present study was to evaluate pregnancy-related changes in autonomic regulatory functions in healthy subjects. We studied cardiovascular autonomic responses to head-up tilt (HUT) in 28 pregnant women during the third trimester of pregnancy and 3 months after parturition. The maternal ECG and non-invasive beat-to-beat blood pressure were recorded in the horizontal position (left-lateral position) and during HUT in the upright position. Stroke volume was assessed from blood pressure signal by using the arterial pulse contour method. Heart rate variability (HRV) was analysed in frequency domain, and baroreflex sensitivity by the cross-spectral and the sequence methods. In the horizontal position, all frequency components of HRV were lower during pregnancy than 3 months after parturition (P < 0.01 to <0.001), while pregnancy had no influence on normalized low frequency and high frequency powers. During pregnancy haemodynamics was well balanced with only minor changes in response to postural change while haemodynamic responses to HUT were more remarkable after parturition. In pregnant women HRV and especially its very low frequency component increased in response to HUT, whereas at 3 months after parturition the direction of these changes was opposite. Parasympathetic deactivation towards term is likely to contribute to increased heart rate and cardiac output at rest, whereas restored sympathetic modulation with modest responses may contribute stable peripheral resistance and sufficient placental blood supply under stimulated conditions. It is important to understand cardiovascular autonomic nervous system and haemodynamic control in normal pregnancy before being able to judge whether they are dysregulated in complicated pregnancies.  相似文献   
107.
The genetic variation of apolipoprotein B has been studied extensively in Finns with the aid of protein and DNA polymorphisms. Population association studies confirmed significant associations between the XbaI polymorphism of the apolipoprotein B gene and elevated serum cholesterol levels, and dietary studies suggested that the XbaI and ins/del polymorphisms might modify the serum lipid response to dietary fat intake. Studies comparing patients and controls, however, did not confirm previous studies suggesting that the multi-allelic variation at the 3'VNTR region of the apolipoprotein B gene was associated with coronary artery disease. The results suggest that the apolipoprotein B gene is involved in the regulation of serum lipid levels. A yet unknown mutation in linkage disequilibrium with the XbaI site may contribute to this regulation.  相似文献   
108.
AbstractObjective: To obtain a deeper understanding of smokers' feelings and to establish co-operative networking groups,the opinions about smoking cessation of health careprofessionals and smokers were studied.Design: Focus group discussions were held in order to gainideas and tools to be used in smoking cessation work, inparticular in network groups. Two focus group discussions forhealth care professionals (n = 7) and one focus groupdiscussion for ex-smokers/smokers (n = 3) were held.Results: The study suggests that problems exist in smokingcessation work among health care professionals. The mainissues among the health care professionals were lack ofmotivation and consistency of approach. Informationconcerning the health risk related to smoking no longerreaches people. New ways of health promotion are desired.Smokers feel that lack of positive support and nicotinedependence are the main problems in their attempts to quit.Conclusions: Society and smokers have the same goal:smoking cessation. However, both parties do not seem toagree on ways of achieving this goal. A local network amonghealth care professionals could motivate and give rise to newmethods of smoking cessation counselling. Positive supportand nicotine replacement therapy could significantlyimprove smokers' success rates. Trained personnel havebetter opportunities for meeting smokers and that is whycessation should be part of the core curriculum and basictraining for health care professionals.  相似文献   
109.
We studied IgG antibody levels to synthetic peptides (p62, E11 and E3) from Epstein-Barr nuclear antigen-1 (EBNA-1) protein sequence in sera of patients with rheumatoid arthritis (RA), in pre-RA and in rheumatoid factor (RF) positive non-RA sera from Finland. Anti-E11 and anti-E3 antibody levels were significantly elevated in RA sera, compared with both RF negative and RF positive nonrheumatoid controls. The concentrations of anti-E11 and anti-E3 antibodies in the preillness sera were lower than those in RA sera. Eight-year followup samples of patients with RA had slightly decreased levels of anti-E3 and anti-E11 antibodies compared with samples taken within 6 months of the disease onset. Anti-p62 antibody levels did not differ significantly between any of the groups studied. Thus, elevated levels of antibodies to 2 of the glycine containing EBNA-1 peptides were associated with clinical RA.  相似文献   
110.
Dietary fibre has been proposed to decrease risk for colon cancer by altering the composition of intestinal microbes or their activity. In the present study, the changes in intestinal microbiota and its activity, and immunological characteristics, such as cyclo-oxygenase (COX)-2 gene expression in mucosa, in pigs fed with a high-energy-density diet, with and without supplementation of a soluble fibre (polydextrose; PDX) (30 g/d) were assessed in different intestinal compartments. PDX was gradually fermented throughout the intestine, and was still present in the distal colon. Irrespective of the diet throughout the intestine, of the four microbial groups determined by fluorescent in situ hybridisation, lactobacilli were found to be dominating, followed by clostridia and Bacteroides. Bifidobacteria represented a minority of the total intestinal microbiota. The numbers of bacteria increased approximately ten-fold from the distal small intestine to the distal colon. Concomitantly, also concentrations of SCFA and biogenic amines increased in the large intestine. In contrast, concentrations of luminal IgA decreased distally but the expression of mucosal COX-2 had a tendency to increase in the mucosa towards the distal colon. Addition of PDX to the diet significantly changed the fermentation endproducts, especially in the distal colon, whereas effects on bacterial composition were rather minor. There was a reduction in concentrations of SCFA and tryptamine, and an increase in concentrations of spermidine in the colon upon PDX supplementation. Furthermore, PDX tended to decrease the expression of mucosal COX-2, therefore possibly reducing the risk of developing colon cancer-promoting conditions in the distal intestine.  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