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   1299篇
  免费   108篇
  国内免费   9篇
耳鼻咽喉   5篇
儿科学   50篇
妇产科学   27篇
基础医学   122篇
口腔科学   19篇
临床医学   75篇
内科学   565篇
皮肤病学   16篇
神经病学   49篇
特种医学   39篇
外科学   218篇
综合类   6篇
预防医学   73篇
眼科学   17篇
药学   43篇
中国医学   2篇
肿瘤学   90篇
  2023年   21篇
  2022年   35篇
  2021年   61篇
  2020年   30篇
  2019年   48篇
  2018年   71篇
  2017年   47篇
  2016年   47篇
  2015年   37篇
  2014年   84篇
  2013年   71篇
  2012年   151篇
  2011年   137篇
  2010年   82篇
  2009年   59篇
  2008年   95篇
  2007年   81篇
  2006年   59篇
  2005年   56篇
  2004年   50篇
  2003年   39篇
  2002年   33篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1998年   4篇
  1994年   2篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   4篇
  1978年   2篇
排序方式: 共有1416条查询结果,搜索用时 265 毫秒
131.
Several reports on angioedema (AE) related to the use of angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) have been published recently. This study reports on the experience gained at the Ear, Nose, and Throat (ENT) Clinic of the University Hospital of Heraklion, Crete. A retrospective chart review of the patients admitted to this clinic, in a 42-month period (1999-2003), and discharged with a diagnosis ENT code for AE was performed (14 eligible patients). A complementary telephone survey was conducted during January 2005. Ten patients responded to our invitation. Of those patients, five were under ACE-I and one was under ARB treatment during the AE episode. The mean length of time between the onset of symptoms and presentation to the hospital was 4.5 hours (range 0.5-12 hours). The mean duration between the initiation of antihypertensive treatment and AE episode was 26.2 months (range 1-60 months). Patients reported that no information was provided about the possible adverse effects of these drugs. Although AE introduced by ACE-I and ARBs is an uncommon side effect, this case series conveys a key message to primary care physicians.  相似文献   
132.
Blue and green sunlight become available for photosynthetic energy conversion through the light-harvesting (LH) function of carotenoids, which involves transfer of carotenoid singlet excited states to nearby (bacterio)chlorophylls (BChls). The excited-state manifold of carotenoids usually is described in terms of two singlet states, S(1) and S(2), of which only the latter can be populated from the ground state by the absorption of one photon. Both states are capable of energy transfer to (B)Chl. We recently showed that in the LH1 complex of the purple bacterium Rhodospirillum rubrum, which is rather inefficient in carotenoid-to-BChl energy transfer, a third additional carotenoid excited singlet state is formed. This state, which we termed S*, was found to be a precursor on an ultrafast fission reaction pathway to carotenoid triplet state formation. Here we present evidence that S* is formed with significant yield in the LH2 complex of Rhodobacter sphaeroides, which has a highly efficient carotenoid LH function. We demonstrate that S* is actively involved in the energy transfer process to BChl and thus have uncovered an alternative pathway of carotenoid-to-BChl energy transfer. In competition with energy transfer to BChl, fission occurs from S*, leading to ultrafast formation of carotenoid triplets. Analysis in terms of a kinetic model indicates that energy transfer through S* accounts for 10-15% of the total energy transfer to BChl, and that inclusion of this pathway is necessary to obtain a highly efficient LH function of carotenoids.  相似文献   
133.
Abstract We report the case of a 44-year-old white man who presented with progressively worsening crampy abdominal pain and distention. Deterioration of his clinical picture along with leukocytosis and radiographic evidence of severe colonic dilation rendered exploratory laparotomy necessary. Greatly distended and inflamed transverse and descending colon were evident and an extended left colectomy was performed. Characteristic changes of leukocytoclastic vasculitis in the serosal and muscular layers of the resected colon were demonstrated at histopathologic examination. Systemic leukocytoclastic vasculitis, usually coexisting with Henoch-Schönlein purpura, commonly affects the small bowel with clinical evidence of ischemia or bleeding. Colon involvement is infrequently reported in the context of systemic disease. Isolated colonic leukocytoclastic vasculitis without extraintestinal manifestations is rare. A previously unreported case of localized leukocytoclastic vasculitis of the left colon resulting in the impressive presentation of megacolon, without the presence of any precipitating factor or associated systemic disease is presented here, with an overview of the related literature.  相似文献   
134.
We describe histologically cases of patients between 31 and 60 years of age who had fibromuscular dysplasia (FMD) in the tunica media (TM) of the left ventricle papillary muscles (PM) arteries. We also compared them with our previous findings in subjects younger than 30 years of age. We examined histologically samples taken from the tip of the anterior PM of the left ventricle in 200 healthy male hearts. In 33 cases (16.5 %), FMD was in the TM. We divided these cases into three subgroups (A, B, C) based on the degree of replacement of smooth muscle cells by fibrous tissue, and thus identified 17, 11 and 5 cases, respectively. Until the age of 41, the typical lesions were often localized within the TM. Beyond that age, the fibrous tissue increased in the TM wall and in the surrounding area of the vessels, causing dysfunction of the PM. Degenerative lesions, as well as inflammatory infiltration, were found after the age of 53. The findings of this study will be useful to cardiologists and cardiac surgeons, in pointing out that, after the age of 44 years old, some PM and their supporting valves may present a degree of dysfunction.  相似文献   
135.
Genetic and antigenic characterization of 37 representative influenza A(H3N2) virus strains isolated in Greece during the 2011-2012 winter season was performed to evaluate matching of the viruses with the seasonal influenza vaccine strain A/Perth/16/2009. Hemagglutinin gene sequence analysis revealed that all Greek strains clustered within the Victoria/208 genetic clade. Furthermore, substitutions in the antigenic and glycosylation sites suggested potential antigenic drift. Our hemagglutination inhibition (HI) analysis showed that the Greek viruses were Perth/16-like; however, these viruses were characterized as Victoria/208-like when tested at the United Kingdom WHO Collaborating Centre (CC) with HI assays performed in the presence of oseltamivir, a finding consistent with the genetic characterization data. Variability in the HI test performance experienced by other European laboratories indicated that antigenic analysis of the A(H3N2) virus has limitations and, until its standardization, national influenza reference laboratories should include genetic characterization results for selection of representative viruses for detailed antigenic analysis by the WHO CCs.  相似文献   
136.
As the detection rate of HPV‐DNA in anal carcinoma commonly exceeds 90%, a comparison between sole HPV‐positive and HPV‐negative cancers with respect to treatment response following chemoradiotherapy (CRT) and long‐term oncological outcome is challenging. Against this background, we aimed to assess HPV types and HPV DNA load in formalin‐fixed paraffin‐embedded tissue (FFPE) of 95 patients treated with standard CRT for anal cancer to correlate viral load (≤/> median) with local failure, distant metastases, cancer‐specific (CSS) and overall survival (OS) rates. Various clinicopathologic parameters and the immunohistochemical marker p16INK4a were evaluated for any correlation with HPV16 DNA load and were included in uni‐ and multivariate analyses. The overall prevalence of HPV DNA was 95.8% with HPV16 monoinfection being the most commonly encountered HPV type (78.9%), followed by HPV16 and 31, 35, 39, 44, 58, 66 and 81 dual infection in 9 patients (9.5%). HPV16 DNA load was significantly associated with p16INK4a expression (p = 0.001). Patients with HPV16 DNA load ≤ median and low p16INK4a expression showed significantly worse local control (HPV16 DNA load: univariate p = 0.023, multivariate p = 0.042; p16INK4a: univariate p = 0.021), and OS (HPV16 DNA load: univariate p = 0.02, multivariate p = 0.03). Moreover, a combined HPV16 DNA load and p16INK4a variable revealed a significant correlation to decreased local failure, and increased CSS and OS (p = 0.019, p = 0.04 and p = 0.031). In conclusion, these data indicate that HPV16 DNA load and p16INK4a expression are significant prognostic factors for local tumor control and overall survival of patients with anal SCC following CRT.  相似文献   
137.
138.
139.
ABSTRACT: BACKGROUND: Research on length of stay (LOS) of psychiatric inpatients is an under-investigated issue. In this naturalistic study we investigated factors which affect LOS in two groups of patients focusing particularly on the impact on LOS of medical comorbidity severe enough to require referral. METHODS: Active medical comorbidity was quantified using referral as the criterion. The study sample comprised of with 200 inpatients with the diagnosis of schizophrenia and 228 inpatients suffering from bipolar disorder (type I or II). Jonckheere and Mann-Whitney tests were used to estimate the influence of referrals on LOS, and regression analyses isolated variables associated with LOS separately for each group. RESULTS: Half of the patients needed one or more referrals for a non-psychiatric problem. The most common medical condition of patients with bipolar disorder was arterial hypertension. Inpatients with schizophrenia suffered mostly from an endocrine/metabolic disease - 12% of referrals were for Hashimoto's thyroiditis. A positive linear trend was found between LOS and number of referrals in both groups, the effect was greater for schizophrenia patients. The effect of referrals on LOS was verified by regression in both groups. Overall, referred patients showed greater improvement in GAF compared to controls. CONCLUSIONS: To our knowledge this is the first study to investigate physical comorbidity in psychiatric inpatients using the criteria of referral to medical subspecialties. Comorbidity severe enough to warrant referral is a significant determinant of hospital stay. This insight may prove useful in health care planning. The results show lack of effective community care in the case of schizophrenia and negative symptoms may be the cause of this. Our findings call for more attention to be paid to the general medical needs of inpatients with severe mental health and concurrent severe medical comorbidity.  相似文献   
140.
OBJECTIVES: This study was designed to evaluate the relationship between plasma leptin and prognosis in patients with angiographically confirmed coronary atherosclerosis. BACKGROUND: Experimental studies suggest that leptin, an adipose tissue-derived hormone, exerts important cardiovascular effects. METHODS: Study subjects were recruited prospectively from a cohort of patients undergoing clinically indicated coronary angiography (n = 382). The median duration of follow-up was four years. Follow-up information was available for 361 patients. RESULTS: The combined end point of cardiac death, myocardial infarction (MI), cerebrovascular accident, or re-vascularization occurred in 44 subjects. In the simple Cox model, leptin had a significant (p < 0.001) non-linear/cubic univariate relationship with the combined end point. Other variables associated with prognosis in the univariate analysis were body mass index (BMI), prior MI, insulin resistance, C-reactive protein (CRP), fibrinogen, and number of coronary vessels with >50% stenosis. A positive relationship between leptin and prognosis was also seen when leptin levels were split by quintiles, with a hazard ratio of 6.46 for the highest quintile. The only two variables significantly associated with the combined end point in the multivariate Cox model were leptin (p = 0.004) and number of coronary vessels with >50% stenosis (p < 0.001). A similar relationship between leptin and prognosis was observed when leptin was adjusted for BMI. CONCLUSIONS: In patients with angiographically confirmed coronary atherosclerosis, leptin is a novel predictor of future cardiovascular events independent of other risk factors, including lipid status and CRP.  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