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   427篇
  免费   22篇
耳鼻咽喉   5篇
儿科学   8篇
妇产科学   6篇
基础医学   70篇
口腔科学   6篇
临床医学   37篇
内科学   98篇
皮肤病学   15篇
神经病学   32篇
特种医学   10篇
外科学   104篇
综合类   5篇
预防医学   16篇
眼科学   15篇
药学   10篇
肿瘤学   12篇
  2024年   1篇
  2023年   4篇
  2022年   11篇
  2021年   12篇
  2020年   6篇
  2019年   9篇
  2018年   14篇
  2017年   14篇
  2016年   9篇
  2015年   14篇
  2014年   17篇
  2013年   11篇
  2012年   39篇
  2011年   37篇
  2010年   24篇
  2009年   19篇
  2008年   29篇
  2007年   26篇
  2006年   17篇
  2005年   14篇
  2004年   16篇
  2003年   12篇
  2002年   14篇
  2001年   9篇
  2000年   11篇
  1999年   10篇
  1998年   9篇
  1996年   7篇
  1995年   2篇
  1994年   4篇
  1992年   4篇
  1991年   3篇
  1989年   3篇
  1988年   3篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1972年   1篇
  1970年   1篇
  1966年   1篇
排序方式: 共有449条查询结果,搜索用时 15 毫秒
101.
The 4G/5G polymorphism of the plasminogen activator inhibitor type I (PAI-I) gene is involved in coronary artery disease (CAD), with the highest risk in 4G/4G homozygotes. The role of PAI-I polymorphism in patients suffering from CAD and history of sudden cardiac death (SCD) has not been addressed yet. We studied the frequency distribution of the PAI-I gene to test the hypothesis that the 4G/4G genotype favors myocardial ischemia and, even in the absence of acute infarction, promotes SCD in patients with CAD. Methods: The PAI-I 4G/5G genotypes and PAI-I antigen plasma levels were determined in 97 patients with CAD and a history of SCD treated with an implantable cardioverter defibrillator (ICD) (defibrillator group) comparing to 113 patients with CAD but no history of SCD (control group). Results: The defibrillator group consisted of significantly more 4G/4G homozygotes and higher PAI-I levels than the control group (44% vs. 24%, 173+/-41 vs. 144+/-49 ng/ml; P<.01). The carriers of 4G allele had a significantly higher risk for SCD (odds ratio (OR) 1.9) with the highest risk in the 4G/4G genotype (OR 3.6, P<.01). Conclusion: These results suggest that the PAI-I 4G/4G genotype is associated with SCD in patients suffering from CAD.  相似文献   
102.
Purpose: Interleukin‐1 (IL‐1) is known to have an important role in pathogenesis of Graves' ophthalmopathy (GO). Polymorphisms in IL‐1 gene have been associated with autoimmune reactions. This study aimed to investigate the association of GO with single‐nucleotide polymorphisms (SNPs) in the IL‐1 family (IL‐1α, IL‐1β, IL‐1 receptor [IL‐1R] and IL‐1 receptor antagonist [IL‐1RA]). Methods: A total of 57 patients of Graves' disease without GO, 50 patients with GO and 140 healthy controls were enrolled. Patients were recruited consecutively from the outpatient endocrine clinic of a large university general hospital. Cytokine typing was performed by the polymerase chain reaction with sequence‐specific primers assay. The allele and genotype frequencies of the following polymorphisms were determined: IL‐1α (?889C/T), IL‐1β (?511C/T), IL‐1β (+3962C/T), IL‐1R (Pst‐1 1970C/T) and IL‐1RA (Mspa‐1 11100C/T). Genotype distributions among patients were in Hardy–Weinberg equilibrium for all polymorphisms. Results: Among the five SNPs studied, the frequencies of the T allele and the TT genotype of IL‐1α (?889C/T) were significantly higher among patients with GO than those without GO (odds ratio [OR] = 2.16, 95% confidence interval [CI] = 1.25–3.74; P = 0.006 and 5.67, 95% CI = 1.66–49.34; P = 0.005, respectively). For IL‐1RA (Mspa‐1 11100C/T), the frequencies of the C allele and the CC genotype were significantly higher among patients with GO (OR = 2.31, 95% CI = 1.34–4.00; P = 0.004 and 6.73 95% CI = 1.94–23.36; P = 0.004, respectively; P < 0.01). No significant association was found for other SNPs. Conclusion: This is the first study to show a positive correlation between polymorphisms in the IL‐1α and IL‐1RA genes and susceptibility to GO. These findings promote further research into genetic correlates of GO.  相似文献   
103.
A recent study (Fernandez et al., Thromb. Haemostas. 1987; 57: 286-93) demonstrated that when rabbits were injected with the minimum weight of a variety of glycosaminoglycans required to inhibit tissue factor-induced thrombus formation by approximately 80%, exogenous thrombin was inactivated approximately twice as fast in the post-treatment plasmas as the pre-treatment plasmas. In this study, we investigated the relationship between inhibition of thrombus formation and the extent of thrombin inhibition ex vivo. We also investigated the relationship between inhibition of thrombus formation and inhibition of prothrombin activation ex vivo. Four sulfated polysaccharides (SPS) which influence coagulation in a variety of ways were used in this study. Unfractionated heparin and the fraction of heparin with high affinity to antithrombin III potentiate the antiproteinase activity of antithrombin III. Pentosan polysulfate potentiates the activity of heparin cofactor II. At less than 10 micrograms/ml of plasma, all three SPS also inhibit intrinsic prothrombin activation. The fourth agent, dermatan sulfate, potentiates the activity of heparin cofactor II but fails to inhibit intrinsic prothrombin activation even at concentrations which exceed 60 micrograms/ml of plasma. Inhibition of thrombus formation by each sulfated polysaccharides was linearly related to the extent of thrombin inhibition achieved ex vivo. These observations confirm the utility of catalysis of thrombin inhibition as an index for assessing antithrombotic potential of glycosaminoglycans and other sulfated polysaccharides in rabbits. With the exception of pentosan polysulfate, there was no clear relationship between inhibition of thrombus formation and inhibition of prothrombin activation ex vivo.  相似文献   
104.
Unfractionated and low molecular weight (LMW) heparins with good antithrombotic activity invariably catalyze thrombin inhibition and inhibit the appearance of thrombin activity in contact-activated plasma. Conversely, the antithrombotic efficacy of LMW heparins decreases as their ability to catalyze thrombin inhibition and to inhibit the appearance of thrombin activity in plasma decrease. The activated partial thromboplastin time (APTT) has proven a reliable test for assaying unfractionated heparin. We therefore compared 2 unfractionated and 3 LMW heparins on the basis of the minimum concentrations required to double the APTT of normal plasma and by then determined how this anticoagulant effect was achieved. The amount of unfractionated and LMW heparin which doubled the APTT was found to be equivalent to approximately 0.25 antithrombin units. This concentration of each glycosaminoglycan completely inhibited prothrombin activation for 45 s after CaCl2 was added to contact-activated plasma; accelerated thrombin inhibition by purified antithrombin III by approximately 50-fold; and accelerated thrombin inhibition equally by antithrombin III in undiluted plasma. This concentration of the three LMW heparins increased, by approximately 70-fold, the rate of factor Xa inhibition by purified antithrombin III compared to the 50-fold increase seen with the two unfractionated heparins. These results thus suggest that tests based on the inhibition of prothrombin activation and/or on the catalysis of thrombin inhibition provide a useful basis for assigning in vitro potency to both unfractionated and LMW heparins.  相似文献   
105.
BackgroundRandomized controlled trials (RCTs) have demonstrated that bariatric surgery improves glycemic control among people with diabetes. However, evidence from RCTs may not be generalizable to real-world clinical care with unselected patients in routine clinical practice.ObjectivesTo examine long-term glycemic control and glucose-lowering drug regimens following bariatric surgery for people with type 2 diabetes (T2D) in unselected patients in routine clinical practice.SettingPopulation-based cohort study using linked routinely collected real-world data from Ontario, Canada.MethodsIndividuals with T2D who were assessed for bariatric surgery at any referral center in the province between February 2010 and November 2016 were identified and divided into those who received surgery within 2 years of the initial assessment and those who did not.ResultsThere were 3674 people who had bariatric surgery and 1335 who did not. By 2 years, people who had undergone surgery had a significantly lower HbA1C (6.3 ± 1.2 % versus 7.8 ± 1.8 %, P < .0001), and this difference persisted at 3, 4, 5, and 6 years. Even by 6 years, half of those who had undergone surgery remained on no glucose-lowering drugs, and they were nearly 6 times less likely to be on insulin than those who had not undergone surgery.ConclusionsIn real-world clinical care, bariatric surgery was associated with large and sustained improvements in glycemic control.  相似文献   
106.
Twenty-four magnetic resonance (MR) imaging–guided percutaneous adrenal biopsies performed between April 2009 and October 2016 were reviewed retrospectively. Epidemiologic, procedural, and histopathologic data were retrospectively collected. Mean size of tumors was 4.3 cm (range, 1.5–16.0 cm). Mean procedure time was 49 min (range, 24–95 min). Mean needle angulation was 27.7° (range, 0°–60°). Mean depth was 9.6 cm (range, 5.8–13.7 cm). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR imaging–guided biopsy were 95.5%, 100%, 100%, 66.7%, and 95.8%, respectively. There were no immediate or delayed complications. MR imaging guidance seems safe and accurate to target adrenal-gland masses.  相似文献   
107.
108.
ObjectiveThis case‐control study was designed to compare the composition of the predominant oral bacterial microbiome in Alzheimer''s disease (AD) and control group.SubjectA total of 30 adult participants (15 AD and 15 healthy individuals) were entered in this study. The composition of oral bacterial microbiome was examined by quantitative real‐time polymerase chain reaction (qPCR) using bacterial 16S rDNA gene. The levels of systemic inflammatory cytokines in both groups were assessed using enzyme‐linked immunosorbent assays (ELISA).ResultsThe loads of Porphyromonas gingivalis, Fusobacterium nucleatum, and Prevotella intermedia were significantly more abundant in the AD compared to the control group (< 0.05). Although Aggregatibacter actinomycetemcomitans and Streptococcus mutans were relatively frequent in the AD group, no significance difference was observed in their copy number between two groups. Although the concentrations of IL‐1, IL‐6, and TNF‐α were higher in the AD group, there was a significant difference in their levels between the two groups (p < 0.05). Finally, there was a significant relationship between increased number of pathogenic bacteria in oral microbiome and higher concentration of cytokines in patient''s blood.ConclusionOur knowledge of oral microbiome and its exact association with AD is rather limited; our study showed a significant association between changes in oral microbiome bacteria, increased inflammatory cytokines, and AD.  相似文献   
109.
110.
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