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   4316篇
  免费   253篇
  国内免费   54篇
耳鼻咽喉   14篇
儿科学   74篇
妇产科学   83篇
基础医学   506篇
口腔科学   66篇
临床医学   335篇
内科学   1463篇
皮肤病学   70篇
神经病学   514篇
特种医学   202篇
外科学   588篇
综合类   20篇
预防医学   108篇
眼科学   44篇
药学   200篇
中国医学   16篇
肿瘤学   320篇
  2023年   33篇
  2022年   58篇
  2021年   120篇
  2020年   88篇
  2019年   93篇
  2018年   134篇
  2017年   110篇
  2016年   130篇
  2015年   133篇
  2014年   191篇
  2013年   266篇
  2012年   367篇
  2011年   348篇
  2010年   216篇
  2009年   198篇
  2008年   291篇
  2007年   285篇
  2006年   258篇
  2005年   305篇
  2004年   262篇
  2003年   190篇
  2002年   161篇
  2001年   25篇
  2000年   17篇
  1999年   25篇
  1998年   24篇
  1997年   30篇
  1996年   25篇
  1995年   26篇
  1994年   14篇
  1993年   10篇
  1992年   18篇
  1991年   21篇
  1990年   18篇
  1989年   12篇
  1988年   15篇
  1987年   7篇
  1986年   8篇
  1985年   8篇
  1984年   13篇
  1983年   4篇
  1982年   7篇
  1981年   9篇
  1980年   4篇
  1974年   4篇
  1973年   5篇
  1972年   4篇
  1970年   5篇
  1969年   3篇
  1968年   3篇
排序方式: 共有4623条查询结果,搜索用时 740 毫秒
81.
The possibility that isosorbide dinitrate (ISDN) inhibits platelet function in humans has been explored in vitro and in vivo. Incubation of citrated plateletrich plasma from healthy subjects with scalar concentrations (1.25, 12.5 and 125 μg/ml) of ISDN for 5 and 10 minutes resulted in a decrease in platelet aggregation after ADP, adrenaline, and arachidonic acid at the highest drug concentration (mean decrease: 72% [p < 0.01], 56% [p < 0.05] and 62% [p < 0.05], respectively, with the 10-minute incubation). Also, a significant reduction (30%) in generated thromboxane (TX)B2 levels was observed after arachidonic acid (p < 0.01). ISDN was then infused at rate of 4 mg/hour for 30 minutes in 11 patients with angina and at a rate of 30 mg/hour for 20 minutes in 8. The smaller dose, which caused minor changes in arterial pressure and heart rate, was accompanied by a marked, significant decrease in ADP- and adrenaline-induced aggregation, with a nadir at 60 minutes from the infusion stop (decreases of 40% and 51% respectively). Circulating platelet aggregates also decreased, with a minimum (? 41%, p < 0.05) at the end of the infusion. The higher infusion rate, causing marked hemodynamic effects, was not accompanied by the occurrence of clear antiplatelet effects. Thus, ISDN can affect platelet function both in vitro and in vivo. The in vivo effect occurs at lower concentrations than in vitro but is blunted when a marked hemodynamic response occurs.  相似文献   
82.
Chronic skin ulcers, consequence of diabetes and other pathological conditions, heavily compromise the patient life quality and represent a high and constantly growing cost for National Health Services. Autologous platelet‐rich plasma (PRP), has been proposed to treat these lesions. The absence of guidelines for the PRP production and the need of a fresh preparation for each treatment lead us to develop a protocol for the production of an allogenic PRP‐based bioactive membrane (BAM), standardized for platelet concentration and growth factor release. This work compares BAMs obtained starting from two different platelet concentrations. There was no direct correlation between the amount of growth factors released by BAM in vitro and the initial platelet count. However, different release kinetics were noticed for different growth factors, suggesting that they were differently retained by the two BAMs. The angiogenic potential of both BAMs was determined by Luminex Angiogenesis Assay. The biological activity of the factors released by the two BAMs was confirmed by cell proliferation and migration. A diabetic mouse chronic ulcer model was used to define the best PRP therapeutic dose in vivo. Both BAMs induced wound healing by increasing the thickness of the regenerated epidermis and the vessel number. However, a too high platelet concentration resulted in a slowdown of the membrane resorption that interfered with the skin healing. Overall, the results indicate that the BAMs could represent a natural and effective wound healing tool for the treatment of skin ulcers. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
83.
Introduction: Increasing device implantations, patient comorbidities, and longer life expectancy contribute to an increased need for lead extraction. Even if transvenous lead extraction (TLE) is a highly successful procedure, some serious procedural complications are reported. In order to identify those patients who are at higher risk, risk stratification scores were proposed.

Areas covered: The major obstacles to lead extractions are represented by the body’s response to the foreign implanted material and by the following development of fibrotic reaction between the lead and the vascular system. Several clinical factors and device features are associated with major complications and worse outcomes. Although different multiparametric scores predicting the safety and the efficacy of TLE procedures were reported, none of these scores were prospective evaluated.

Expert commentary: A correct risk stratification is needed in order to refer complex patients to centers with proven experience and avoid futile procedures. Furthermore, the identification of high-risk patients allows to perform the extraction procedure in the operating room instead of electrophysiology lab. Albeit some risk scores able to predict adverse event in cardiac lead extraction were described, there are still several limitations to their use and reproducibility.  相似文献   

84.
85.
The increasing use of cobalt oxide (Co3O4) nanoparticles (NPs) in several applications and the suggested genotoxic potential of Co‐oxide highlight the importance of evaluating Co3O4 NPs toxicity. Cyto‐genotoxic and inflammatory effects induced by Co3O4 NPs were investigated in human alveolar (A549), and bronchial (BEAS‐2B) cells exposed to 1–40 µg ml–1. The physicochemical properties of tested NPs were analysed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Cytotoxicity was studied to analyze cell viability (WST1 test) and membrane damage (LDH assay), direct/oxidative DNA damage was assessed by the Formamido‐pyrimidine glycosylase (Fpg)‐modified comet assay and inflammation by interleukin (IL)‐6, IL‐8 and tumor necrosis factor‐alpha (TNF‐α) release (ELISA). In A549 cells, no cytotoxicity was found, whereas BEAS‐2B cells showed a viability reduction at 40 µg ml–1 and early membrane damage at 1, 5 and 40 µg ml–1. In A549 cells, direct and oxidative DNA damage at 20 and 40 µg ml–1 were detected without any effects on cytokine release. In BEAS‐2B cells, significant direct DNA damage at 40 µg ml–1 and significant oxidative DNA damage with a peak at 5 µg ml–1, that was associated with increased TNF‐α release at 1 µg ml–1 after 2 h and increased IL‐8 release at 20 µg ml–1 after 24 h, were detected. The findings show in the transformed alveolar cells no cytotoxicity and genotoxic/oxidative effects at 20 and 40 µg ml–1. In normal bronchial cells, moderate cytotoxicity, direct DNA damage only at the highest concentration and significant oxidative‐inflammatory effects at lower concentrations were detected. The findings confirm the genotoxic‐oxidative potential of Co3O4 NPs and show greater sensitivity of BEAS‐2B cells to cytotoxic and oxidative‐inflammatory effects suggesting the use of different cell lines and multiple end‐points to elucidate Co3O4 NPs toxicity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
86.
Journal of Thrombosis and Thrombolysis - Several studies have shown that T-cells might be involved in pathophysiology of acute coronary syndromes (ACS). Tissue factor (TF) plays a key role in ACS....  相似文献   
87.
Metabolic Brain Disease - Neonatal seizures (NS) occur in the first 28&nbsp;days of life; they represent an important emergency that requires a rapid diagnostic work-up to start a prompt...  相似文献   
88.
The long-term changes of liver stiffness (LS) in patients who achieve viral clearance after direct-acting anti-HCV therapy remain undefined. We conducted a multicentre prospective study to investigate this aspect. Patients with HCV infection treated with DAAs were enrolled from six Italian centres; they underwent clinical, biochemical, ultrasound and transient elastography evaluations before treatment (T0), 12 weeks (SVR12) and 24 months (T24) after the end of therapy. Among the 516 consecutive patients enrolled, 301 had cirrhosis. LS significantly decreased from T0 to SVR (14.3 vs 11.1 kPa, p = .002), with a progressive reduction until T24 (8.7 kPa, p < .001). However, only patients with steatosis and those who developed HCC did not experience a late improvement in LS. Multivariate analysis of baseline and follow-up variables identified steatosis as the only independent predictor of failure of LS improvement (OR 1.802, p = .013). ROC curve analysis of the association of LS with the risk of developing HCC showed that SVR12 ≥14.0 kPa had the highest accuracy (sensitivity 82%, specificity 99%; AUC: 0.774). Multivariate analysis revealed that LS was the only variable independently associated with an increased risk of developing HCC (OR 6.470, p = .035). Achieving an SVR was associated with a progressive, long-term decline of LS, suggesting a late improvement in liver fibrosis, besides the resolution of inflammation. Fatty liver and the development of HCC interfered with late reduction of LS. Patients with an LS ≥14 kPa at 12 weeks after the end of treatment were at higher risk for developing HCC.  相似文献   
89.
There has been a debate about the possibility of a link between silicone breast implants and the onset of systemic connective tissue diseases (eg, scleroderma, systemic lupus erythematosus, rheumatoid arthritis) and other inflammatory pathologies, such as silicone implant associated syndrome and adult Still disease. We report a case of adult Still disease in a patient with a silicone gel breast implant. The disease regressed with steroidal treatment, and the patient is now no longer steroid-dependent, although the implant is still in place.  相似文献   
90.
ObjectivesThis study sought to determine whether the breast gland adipose tissue is associated with different rates of major adverse cardiac events (MACEs) in pre-menopausal women.BackgroundTo our knowledge, no study investigated the impact of breast adipose tissue infiltration on MACEs in pre-menopausal women.MethodsProspective multicenter cohort study conducted on pre-menopausal women >40 years of age without cardiovascular disease and breast cancer at enrollment. The study started in January 2000 and ended in January 2009, and the end of the follow-up for the evaluation of MACEs was in January 2019. Participants underwent mammography to evaluate breast density and were divided into 4 groups according to their breast density. The primary endpoint was the probability of a MACE at 10 years of follow-up in patients staged for different breast deposition/adipose tissue deposition.ResultsThe propensity score matching divided the baseline population of 16,763 pre-menopausal women, leaving 3,272 women according to the category of breast density from A to D. These women were assigned to 4 groups of the study according to baseline breast density. At 10 years of follow-up, we had 160 MACEs in group 1, 62 MACEs in group 2, 27 MACEs in group 3, and 16 MACEs in group 4. MACEs were predicted by the initial diagnosis of lowest breast density (hazard ratio: 3.483; 95% confidence interval: 1.476 to 8.257). Further randomized clinical trials are needed to translate the results of the present study into clinical practice. The loss of ex vivo breast density models to study the cellular/molecular pathways implied in MACE is another study limitation.ConclusionsAmong pre-menopausal women, a higher evidence of adipose tissue at the level of breast gland (lowest breast density, category A) versus higher breast density shows higher rates of MACEs. Therefore, the screening mammography could be proposed in overweight women to stage breast density and to predict MACEs. (Breast Density in Pre-menopausal Women Is Predictive of Cardiovascular Outcomes at 10 Years of Follow-Up [BRECARD]; NCT03779217)  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