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   7580篇
  免费   286篇
  国内免费   25篇
耳鼻咽喉   17篇
儿科学   111篇
妇产科学   52篇
基础医学   415篇
口腔科学   36篇
临床医学   513篇
内科学   1998篇
皮肤病学   15篇
神经病学   130篇
特种医学   319篇
外科学   3527篇
综合类   65篇
预防医学   86篇
眼科学   21篇
药学   100篇
  1篇
中国医学   7篇
肿瘤学   478篇
  2024年   4篇
  2023年   610篇
  2022年   726篇
  2021年   874篇
  2020年   721篇
  2019年   343篇
  2018年   349篇
  2017年   259篇
  2016年   278篇
  2015年   297篇
  2014年   708篇
  2013年   572篇
  2012年   259篇
  2011年   96篇
  2010年   349篇
  2009年   325篇
  2008年   91篇
  2007年   115篇
  2006年   121篇
  2005年   59篇
  2004年   53篇
  2003年   39篇
  2002年   71篇
  2001年   52篇
  2000年   49篇
  1999年   79篇
  1998年   89篇
  1997年   25篇
  1996年   47篇
  1995年   32篇
  1994年   34篇
  1993年   16篇
  1992年   9篇
  1991年   8篇
  1990年   9篇
  1989年   10篇
  1988年   13篇
  1987年   10篇
  1986年   12篇
  1985年   5篇
  1984年   13篇
  1983年   10篇
  1982年   8篇
  1981年   8篇
  1980年   5篇
  1979年   3篇
  1978年   11篇
  1975年   3篇
  1972年   3篇
  1970年   3篇
排序方式: 共有7891条查询结果,搜索用时 15 毫秒
941.
Pulmonary endothelial injury is central in the pathogenesis of acute lung injury (ALI). The MAPK signaling cascades are generally thought to be involved in the molecular mechanism underlying the ALI development, but their roles in pulmonary endothelial injury is poorly understood. We thus examined the involvement of the MAPK family member in inflammatory responses of human pulmonary microvascular endothelial cells (HPMVECs) stimulated with LPS and IFN-γ. HPMVECs were found to exhibit the upregulation of expression of Toll-like receptor 4 by IFN-γ, resulting in potentiation of inflammatory cytokine release by LPS stimulation. All MAPKs, ERK1/2, JNK, and p38, were activated by simultaneous stimulation with LPS/IFN-γ. JNK activation in cells stimulated with LPS/IFN-γ was significantly potentiated by the two different p38 inhibitors, SB203580 and RWJ67657, suggesting the negative regulation of JNK activation by p38 in HPMVECs. The mRNA and protein expression levels of ICAM-1 were eliminated by the JNK inhibitor, suggesting that ICAM-1 expression is positively regulated by JNK. The p38 inhibitor significantly enhanced ICAM-1 expression. ERK1/2 activation was not responsible for the LPS/IFN-γ-induced ICAM-1 upregulation in HPMVECs. THP-1 monocyte adhesion to HPMVECs under LPS/IFN-γ stimulation was inhibited by the JNK inhibitor and enhanced by the p38 inhibitor. We conclude that, in HPMVECs stimulated with LPS/IFN-γ, JNK mediates ICAM-1 expression that can facilitate leukocyte adherence and transmigration, while p38 MAPK negatively regulates the upregulation of ICAM-1 through inhibition of JNK activation.  相似文献   
942.
943.
A 68-year-old man had undergone ascending aortic replacement for acute type A aortic dissection. Three months later, he had a new aortic dissection with an ulcer-like projection located in the aortic arch with suspected graft infection. An emergent redo total aortic arch and root replacement was performed because of the coexistence of a fragile aortic root wall. The extensive redo procedure necessitated a very long aortic cross-clamping time (516 min). After 25 min of assisted circulation, he was easily weaned from the cardiopulmonary bypass. Finally, an omental flap was harvested to cover the graft. Postoperative ECG and CK-MB examinations showed no significant myocardial injury. He had no symptoms of heart failure and was discharged after a month of antibiotic therapy. One-year follow-up UCG study revealed no abnormal findings except for signs of pericardial adhesion.  相似文献   
944.
Background: The assessment of left ventricular (LV) structure and function is important in the evaluation of hypertensive heart disease, as it provides information on the cardiovascular morbidity and mortality. Aortic knob width (AKW) is a measurement of radiographic structure formed by the foreshortened aortic arch and a portion of the descending aorta. The main aim of this study was to investigate the relation between AKW on the routine chest radiography and subclinical LV dysfunction in hypertensive patients.

Patients and Methods: A total of 144 patients with hypertension admitted to the cardiology outpatients clinic were enrolled consecutively. The patients were divided into two groups according to tissue Doppler-derived myocardial performance index (MPI): subclinical LV dysfunction group (abnormal MPI ≥ 0.5, n = 85) and absence of subclinical LV dysfunction group (normal MPI< 0.5, n = 59).

Results: Patients with subclinical LV dysfunction were older (60 ± 8 vs. 54 ± 8, p = 0.001). Left ventricular mass index (LVMI) (96 ± 27 vs. 74 ± 24, p < 0.001) and prevalence of LV hypertrophy (28 vs. 8%, p = 0.011) were significantly different between two groups. Patients with subclinical LV dysfunction had higher AKW (42 ± 6 vs. 34 ± 5, p < 0.001) compared with patients without subclinical LV dysfunction. There was a significant correlation between MPI and AKW (r = 0.7, p < 0.001). Multiple logistic regression analysis showed that AKW (β = 0.617, p = 0.001) and posterior wall thickness (PWth) (β = 1.189, p = 0.021) were independently associated with subclinical LV dysfunction. Analysis using the Receiver Operating Characteristic (ROC) curve has demonstrated that aortic knob of 37 mm constitutes the cutoff value for the presence of subclinical LV dysfunction with 85.9% sensitivity and 86.4% specificity (The Area under the Curve ± Standard Error (AUC±SE) = 0.916 ± 0.024, p < 0.001).

Conclusion: AKW may provide important predictive information on subclinical LV dysfunction in patients with hypertension.  相似文献   

945.

Background

Intrapulmonary lymph nodes (IPLNs) are often recognized as sub-centimeter solid pulmonary nodules (SCPNs). The present study investigated their clinical and pathological characteristics to allow clinicians to distinguish them from malignant nodules.

Methods

Among 194 SCPNs surgically resected between 2006 and 2016, 26 IPLNs were investigated histopathologically. In addition, 145 resected malignant SCPNs were compared radiographically with the 26 IPLNs.

Results

Radiographically, most IPLNs were in a middle or lower lobe, and all lesions were within 20?mm of the visceral pleura. Enlargement was seen in one lesion. Three lesions demonstrated linear density contiguous to pleura (LD), and 13 lesions were adjacent to the peripheral pulmonary vein (APV). Microscopically, all IPLNs showed adjacency to pulmonary veins, 23 showed interlobular septa extending from the IPLN, and 18 were surrounded by a dilatated lymphoid channel. Radiographical findings of LD and APV were also seen in malignant SCPNs (LD, 12/145; APV, 25/145). Comparative analysis revealed that enlargement and APV were significant predictors differentiating IPLNs from malignant SCPNs. The sensitivity/specificity of enlargement and APV were 92%/92% and 17%/50%, respectively.

Conclusions

IPLNs show typical high-resolution computed tomography findings that reflect their histopathological characteristics. Such findings help identify IPLNs prior to surgery. Specifically, enlargement and APV may differentiate IPLNs from malignant SCPNs. However, atypical cases are also possible, and radiological findings are not specific for differentiating IPLNs from malignant lesions. Thus, clinicians should consider surgical exploration when diagnosing SCPNs.  相似文献   
946.
947.
948.

Introduction:

Advances in medical and surgical care have made it possible for an increasing number of patients with Congenital Heart disease (CHD) to live into adulthood. Transposition of the great vessels (TGV) is the most common cyanotic congenital cardiac disease where the right ventricle serves as systemic ventricle. It is not uncommon for these patients to have systemic ventricular failure requiring transplantation.

Study Design:

Hemodynamic decompensation in these patients can be swift and difficult to manage. Increasingly percutaneous LVAD''s such as the Impella (Abiomed, Mass, USA) are gaining popularity in these situations owing to their relative ease of placement, both in and outside of the operating room.

Conclusion:

In this paper we demonstrate that Impella (IMP) CP placement through the axillary artery approach shows to be suitable option for short term cardiac support and improvement of end organ perfusion in anticipation of cardiac transplantation.  相似文献   
949.
950.
  • Complex arch anatomy (type 2, type 3) and bovine configuration were identified in 34.4% and 20.5% of carotid stent patients, respectively.
  • Catheter manipulation time (CMT), rather than arch complexity per se, was the only independent predictor of adverse events after carotid stenting.
  • Careful attention to patient selection, preprocedural planning, and stent technique are important to ensure success.
  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