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   9082篇
  免费   287篇
  国内免费   56篇
耳鼻咽喉   96篇
儿科学   166篇
妇产科学   64篇
基础医学   1060篇
口腔科学   204篇
临床医学   592篇
内科学   2651篇
皮肤病学   123篇
神经病学   532篇
特种医学   322篇
外科学   1507篇
综合类   24篇
一般理论   1篇
预防医学   142篇
眼科学   122篇
药学   483篇
  2篇
中国医学   12篇
肿瘤学   1322篇
  2024年   55篇
  2023年   100篇
  2022年   192篇
  2021年   324篇
  2020年   176篇
  2019年   224篇
  2018年   224篇
  2017年   188篇
  2016年   240篇
  2015年   226篇
  2014年   290篇
  2013年   359篇
  2012年   647篇
  2011年   702篇
  2010年   423篇
  2009年   333篇
  2008年   564篇
  2007年   587篇
  2006年   583篇
  2005年   547篇
  2004年   523篇
  2003年   505篇
  2002年   496篇
  2001年   71篇
  2000年   74篇
  1999年   78篇
  1998年   101篇
  1997年   74篇
  1996年   41篇
  1995年   58篇
  1994年   48篇
  1993年   45篇
  1992年   35篇
  1991年   49篇
  1990年   25篇
  1989年   26篇
  1988年   24篇
  1987年   9篇
  1986年   20篇
  1985年   16篇
  1984年   18篇
  1983年   10篇
  1982年   16篇
  1981年   10篇
  1980年   8篇
  1979年   12篇
  1978年   6篇
  1977年   14篇
  1976年   5篇
  1969年   4篇
排序方式: 共有9425条查询结果,搜索用时 12 毫秒
81.
82.
We report a case of lung adenocarcinoma in which cystic lesions enlarged and multiloculated over 2 years. Histological examination of the resected specimen found proliferation of nonmucinous adenocarcinoma cells along the alveolar walls, revealing bronchioloalveolar cell carcinoma type extension. In cystic lesions, particularly those not associated with inflammation, lung adenocarcinoma, particularly bronchioloalveolar cell carcinoma type, should be a diagnostic consideration. .  相似文献   
83.
Endomyocardial biopsy (EMB) and late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) imaging performed at baseline are both used to evaluate the extent of myocardial fibrosis. However, no study has directly compared the effectiveness of these diagnostic tools in the prediction of left ventricular reverse remodeling (LVRR) and prognosis in response to therapy in patients with idiopathic dilated cardiomyopathy (IDCM). Seventy-five patients with newly diagnosed IDCM who were undergoing optimal therapy were assessed at baseline using LGE-CMR imaging and EMB; the former measured LGE area and the latter measured collagen volume fraction (CVF) as possible predictive indices of LVRR and cardiac event-free survival. Among all the baseline primary candidate factors with P < 0.2 as per univariate analysis, multivariate analysis indicated that only LGE area was an independent predictor of subsequent LVRR (β = 0.44; 95 % confidence interval (CI) 0.87–2.53; P < 0.001), as indicated by decreasing left ventricular end-systolic volume index over the 1-year follow-up. Kaplan–Meier curves indicated significantly lower cardiac event-free survival rates in patients with LGE at baseline than in patients without (P < 0.01). By contrast, there was no significant difference in prognosis between patients with CVF values above (severe fibrosis) and below (mild fibrosis) the median of 4.9 %. Cox proportional hazard analysis showed that LGE area was an independent predictor of subsequent cardiac events (hazard ratio 1.06; 95 % CI 1.02–1.10; P ≤ 0.01). The degree of myocardial fibrosis estimated by baseline LGE-CMR imaging, but not that estimated by baseline EMB, can predict LVRR and cardiac event-free survival in response to therapy in patients with newly diagnosed IDCM.  相似文献   
84.
BackgroundPolymer-free biolimus A9-coated coronary stent (DCS) has novel features which lead to the expectation of better arterial healing. However, comparisons of intravascular status between DCS and drug-eluting stents (DES), and robust real-word clinical assessments of DCS have been lacking to date.MethodsFrom September 2017 to September 2018, we evaluated the intra-vascular status of 74 DCS implanted in 55 lesions from 43 patients using coronary angioscopy (CAS) approximately one year after implantation from a cohort of 219 lesions in 158 patients. We set 239 second-generation durable-polymer DES (DP-DES) implanted in 211 lesions from 180 patients from a cohort of 2652 lesions in 1914 patients as the control. Angioscopic images were analyzed to determine (1) the dominant degree of neointimal coverage (NIC) over the stent; (2) the heterogeneity of NIC; (3) yellow color grade of the stented segment; and (4) the presence of intra-stent thrombus. The primary outcome was the incidence of thrombus and secondary outcomes were the other CAS findings, and the 1-year clinical outcomes which included target lesion revascularization (TLR) and major adverse cardiac events (MACE). To minimize inter-group differences in baseline characteristics, propensity score matching was performed for clinical outcomes.ResultsIncidence of thrombus adhesion was similar in DCS and DP-DES groups (28.4% versus 22.6%, p = 0.31). However, the dominant NIC grade was significantly higher in DCS (p < 0.001), while NIC was more heterogeneous in DCS than in DP-DES (p = 0.001). Maximum yellow color grade was similar (p = 0.22). After propensity score matching, 202 lesion pairs from 146 patient pairs were retained for analysis. The cumulative incidence of TLR (4.6% versus 3.8%, p = 0.38) and MACE (11.6% versus 11.7%, p = 0.84) was similar for DCS and DP-DES.ConclusionsDCS showed thrombus adhesion and clinical outcomes at 1 year similar to DP-DES. DCS can thus be used with similar safety and efficacy as DP-DES.  相似文献   
85.
Background/Objectives: This study aimed to elucidate the efficacy of CT findings and perioperative characteristics to predict post-pancreatectomy hemorrhage (PPH): a critical complication after pancreaticoduodenectomy.MethodsThe records of 590 consecutive patients who underwent pancreaticoduodenectomy at three institutes between 2012 and 2018 were included. The presence of a vascular wall abnormality or ascites with high density (vascular abnormality) on postoperative day (POD) 5–10 contrast-enhanced CT (early CT), perioperative characteristics, and any PPH or pseudoaneurysm formation (PPH events) were analyzed through a multivariate analysis.ResultsPPH events occurred in 48 out of 590 patients (8%). The vascular abnormality on early CT and the C-reactive protein (CRP) value on POD 3 were independent risk factors for PPH events after POD5 (vascular abnormality: odds ratio 6.42, p = 0.001; CRP on POD 3: odds ratio 1.17, p = 0.016). The sensitivity of vascular abnormality for PPH events was 24% (7/29), and the positive predictive value was 30% (7/23). The combination of vascular abnormality and a high CRP value (≥15.5 mg/dL) on postoperative day 3 had a higher positive predictive value of 64% (7/11) than the vascular abnormality alone. None of the seven PPH events that occurred more than one month after surgery were foreseen via early CT.ConclusionThe combination of vascular abnormality and high CRP value was associated with increasing risk of PPH events after pancreaticoduodenectomy, but the low sensitivity of early CT must be noted as an important shortcoming. The normal findings on early CT could not eliminate the risk of late PPH.  相似文献   
86.
Background and aim  Narrow band imaging (NBI) is a novel endoscopy system, which enables a clear visualization of the mucosal vasculature of the gastrointestinal tract. The aim of this study is to determine whether this system may be of value for assessing the disease severity in ulcerative colitis (UC). Materials and methods  We observed the mucosal vascular pattern (MVP) in 157 colorectal segments of 30 patients with UC using both conventional and NBI colonoscopy. The MVP was determined to be normal or distorted under conventional colonoscopy and, subsequently, to be clear or obscure under NBI colonoscopy. The histologic variables in each segment were assessed in biopsy specimen. The possible correlation between MVP and the histologic grade of inflammation was evaluated. Results  The MVP under conventional colonoscopy was normal in 60 segments while it was distorted in 97 segments. In all of the former 60 segments, their MVP was clear under NBI colonoscopy. The MVP in the latter 97 segments were determined to be clear (n = 44) or obscure (n = 53) under NBI colonoscopy. Acute inflammatory cell infiltrates (26% vs. 0%, p = 0.0001), goblet cell depletion (32% vs. 5%, p = 0.0006), and basal plasmacytosis (2% vs. 21%, p = 0.006) were more frequently observed in segments with an obscure MVP than in those with a clear MVP. Conclusion  NBI colonoscopy may be of value for determining the grade of inflammation in patients with quiescent UC.  相似文献   
87.
Background  Recent studies have shown that indigenous hepatitis E virus (HEV) strains cause hepatitis E in industrialized countries. We aimed to clarify the characteristics of HEV infection in sporadic hepatitis patients during the last decade in Miyagi, northeast Japan. Methods  We analyzed 94 serum samples obtained from acute or fulminant hepatitis patients of non-A, non-B, and non-C etiology between 1999 and 2008. Antibody to HEV (anti-HEV) was assayed, and patients who were positive for IgM- and/or IgA-class anti-HEV were diagnosed with hepatitis E. HEV RNA was tested in these patients, and phylogenetic analysis was performed. The occurrence of hepatitis E was compared with that of hepatitis A. Results  Eight acute hepatitis patients (8.5%) were diagnosed with hepatitis E, and HEV RNA was detectable in seven patients. Five isolates of HEV were segregated into genotype 3 and the remaining two isolates into genotype 4. The year of the occurrence of hepatitis E was distributed almost equally from 1999 to 2008, whereas the cases of acute hepatitis A (n = 16) have decreased markedly in the last several years. In 2004–2008, the occurrence of hepatitis E was greater than that of hepatitis A (five cases vs. one case). As for seasonality, hepatitis E occurred more frequently from September to December than hepatitis A (five cases vs. four cases), although less frequently from January to April (one case vs. seven cases). Conclusion  The occurrence of hepatitis E has not decreased during the last decade in northeast Japan, in contrast to hepatitis A. The nucleotide sequence data reported in this study have been assigned GenBank/EMBL/DDBJ accession numbers AB206467 and AB453332–AB453337.  相似文献   
88.
    
ObjectiveWe describe a case of intracranial and extracranial multiple arterial dissecting aneurysms in rheumatoid arthritis (RA).Case PresentationA 29-year-old man with a medical history of RA since 18 years of age was admitted to our hospital for vomiting, dysarthria, and conscious disturbance. At 23, he underwent ligation of the left internal carotid artery (ICA) with superficial temporal artery to middle cerebral artery anastomosis because of acute infarct of the left hemisphere caused by arterial dissection of the left ICA. During the current admission, computed tomography (CT) revealed subarachnoid hemorrhage, and digital subtraction angiography (DSA) demonstrated dissecting aneurysms of the left intracranial vertebral artery (VA) and right extracranial VA. We diagnosed him with a ruptured dissecting aneurysm of the left intracranial VA and performed endovascular parent artery occlusion on the left VA. For the right unruptured VA aneurysm, we performed coil embolization simultaneously. At 2 weeks after the endovascular treatment, follow-up DSA revealed that multiple de novo dissecting aneurysms developed on the origin of the left VA and left and right internal thoracic arteries. Those aneurysms were treated with coil embolization. Other remaining aneurysms on the left thyrocervical trunk, right transverse cervical artery, and both common iliac arteries were treated by conservative therapy. While continuing medical treatment for RA, the patient recovered and was discharged to a rehabilitation hospital.ConclusionConsidering that RA-induced vasculitis can be a potential risk of vascular complications including multiple arterial dissections, physicians should carefully perform endovascular interventional procedures for patients with long-term RA.  相似文献   
89.
Adrenomedullin (AM) is a novel vasodilating peptide involved in the regulation of circulatory homeostasis and implicated in the pathophysiology of cardiovascular disease. We tested the hypothesis that AM also possesses angiogenic properties. Using laser Doppler perfusion imaging, we found that AM stimulated recovery of blood flow to the affected limb in the mouse hind-limb ischemia model. AM exerted this effect in part by promoting expression of vascular endothelial growth factor (VEGF) in the ischemic limb, and immunostaining for CD31 showed the enhanced flow to reflect increased collateral capillary density. By enhancing tumor angiogenesis, AM also promoted the growth of subcutaneously transplanted sarcoma 180 tumor cells. However, heterozygotic AM knockout mice (AM+/-) showed significantly less blood flow recovery with less collateral capillary development and VEGF expression than their wild-type littermates. Similarly, mice treated with AM22-52, a competitive inhibitor of AM, showed reduced capillary development, and growth of sarcoma 180 tumors was inhibited in AM+/- and AM22-52-treated mice. Notably, administration of VEGF or AM rescued blood flow recovery and capillary formation in AM+/- and AM22-52-treated mice. In cocultures of endothelial cells and fibroblasts, AM enhanced VEGF-induced capillary formation, whereas in cultures of endothelial cells AM enhanced VEGF-induced Akt activation. These results show that AM possesses novel angiogenic properties mediated by its ability to enhance VEGF expression and Akt activity. This may make AM a useful therapeutic tool for relieving ischemia; conversely, inhibitors of AM could be useful for clinical management of tumor growth.  相似文献   
90.
Background : Leukocytapheresis (LCAP) is used as an adjunct therapy for patients with active ulcerative colitis (UC). Although, LCAP is routinely performed at 3,000 mL per session, we were interested to see that if this can be replaced with bodyweight (BW) adjusted volume. Methods : In an open label prospective trial, the clinical response to BW adjusted LCAP (BWA‐LCAP) was evaluated in 14 patients with active UC. Fourteen demography matched UC patients who had been treated with the routine 3,000 mL LCAP were randomly sampled from our database as a control group. All patients were given 10 weekly LCAP sessions. In the BWA‐LCAP group, the processed blood volume (PBV) was set at 30 mL/kg × BW/session. Baseline demographic measures were not significantly different between the two groups. Results : The average PBV in the BWA‐LCAP group was 1971.0 ± 330.0 mL, range 1,020–2,460. In both groups, the average UC clinical disease activity index, the endoscopic index, and the concomitant prednisolone dosage were significantly and equally reduced during the course of 10 LCAP. Accordingly, at the end of the trial, no significant difference was seen in any outcome measure between the two groups. However, a significantly higher incidence of adverse event (AE) was observed in the routine 3,000 mL LCAP group as compared with the BWA‐LCAP group (P < 0.01). Conclusions : The outcomes of this investigation showed that the therapeutic efficacy of LCAP based on 30 mL/kg × BW is similar to the routine 3,000 mL per session LCAP. However, BWA‐LCAP should be favored if one is to see the full potential of LCAP without AE. © 2011 Wiley Periodicals, Inc.  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